MoodleDocs - User contributions [en]

Question type plugin how to

2011-09-07T08:29:36Z

Fpirsch: /* JavaScript and CSS required by your plugin */

{{Questiontype_developer_docs}}

{{Question_development}}

To follow this guide, you need to get hold of the [http://moodle.org/mod/data/view.php?d=13&rid=443 New question type template]. You can get it by checking out the contrib/question/type/TEMPLATE directory from the CVS repository or from the [http://moodle.org/mod/data/view.php?id=6009 modules and plugins database]. The rest of this guide is just a copy of the README.txt file from in there. (Or is the readme file a copy of this page?)

==New question type template README file==

Welcome to the new question type template.

This blank skeleton is a good place to start if you want to implement your own Moodle question type plugin.

Another good way to start is by looking at an existing question type that has good documentation in the code like TODO (if there is one, otherwise we'll hope that Tims will "light the way" :-) )

The latest version of the template can be found in CVS in http://moodle.cvs.sourceforge.net/moodle/contrib/plugins/question/type/TEMPLATE/. Because you want your own copy do a cvs export, not a cvs checkout. The package can also been downloaded from [http://moodle.org/mod/data/view.php?d=13&rid=443 the Modules and plugins database].

The latest version of this help can be read (nicely formatted) at https://docs.moodle.org/en/How_to_write_a_question_type_plugin

'''WARNING, THIS TEMPLATE IS NOT COMPLETE YET!'''

==Getting started==

Before you get to the interesting bit, you need to do a bit of file-renaming and search-and-replacing to turn this generic template into your own question type. You need to have chosen two things

;The identifier for your question type
:This is a string of lowercase letters and perhaps underscores that the Moodle code uses to refer to your question type. This needs to be unique, so perhaps start it with your initials. For example, all the questions types I create while working at the OU will be referred to as ou_something. For the rest of these instructions, I will assume you have chosen ‘''myqtypeidentifier''’.
;The name of your question type
:This is the name that people will see in the Moodle User-interface (in the English translation). For these instructions I will assume you have chosen ‘''My Question Type Name''’.

Then you need to

# Change all the places ''TEMPLATE'' appears in file names to ''myqtypeidentifier''. That is:
#* rename the top level TEMPLATE directory to ''myqtypeidentifier''.
#* rename the language file lang/en_utf8/qtype_''TEMPLATE''.php to lang/en_utf8/qtype_''myqtypeidentifier''.php
#* rename the help file lang/en_utf8/help/''TEMPLATE''/''TEMPLATE''.html to lang/en_utf8/help/''myqtypeidentifier''/''myqtypeidentifier''.html
#* rename the editing form edit_''TEMPLATE''_form.php to edit_''myqtypeidentifier''_form.php.
# Search and replace 'QTYPEID' with ‘''myqtypeidentifier'’ in all the files. You should find:
#* 2 occurrences in the language file (should now be lang/en_utf8/qtype_''myqtypeidentifier''.php after renaming)
#* 1 occurrence in db/install.xml
#* 4 occurrences in simpletest/testquestiontype.php
#* 2 occurrences in edit_''myqtypeidentifier''_form.php
#* 4 occurrences in questiontype.php
# Search and replace 'QTYPENAME' with ‘''My Question Type Name''’ in all the files. You should find:
#* 1 occurrence in the help file (should now be lang/en_utf8/help/''myqtypeidentifier''/''myqtypeidentifier''.html after renaming)
#* 3 occurrences in the language file (should now be lang/en_utf8/qtype_''myqtypeidentifier''.php after renaming)
#* 1 occurrence in edit_myqtypeidentifier_form.php
#* 2 occurrences in questiontype.php
# Search and replace YOURNAME with your name. (This is only in the comments at the top of each file so it is not critical, but surely you want to take credit for your work.) You should find one occurrence in:
#* lang/en_utf8/qtype_''myqtypeidentifier''.php
#* simpletest/testquestiontype.php
#* edit_''myqtypeidentifier''_form.php
#* questiontype.php
# Search and replace YOUREMAILADDRESS with your email address. (Again, this is only in the file header comments, but it is helpful if people can contact you if they have any questions about your code.)
#* There should be one occurrence of YOUREMAILADDRESS in each of the files listed under YOURNAME.
# Search and replace YOURPACKAGENAME with a package name for your code. This is used by PHPdocumentor when building the documentation for your classes. I suggest you make up one package name for all the question types you write. For example all the question types I write are in the package ou_questiontypes.
#* There should be one occurrence of YOURPACKAGENAME in each of the files listed under YOURNAME.
# Edit icon.gif to make an icon that represents your question type.
# Move your new question type folder in the question/type folder of your Moodle development codebase, so you can test the code as you work on it.

==Now for the interesting bit==

Now you need to write the code to

# Describe any database tables you need in db/install.xml. If you don't need to create any database tables, you can delete the db directory.
# Edit edit_''myqtypeidentifier''_form.php to create the question editing form.
# Create the template that will display the question to the student. This is in display.html. To make good flexible formatting you should use CSS classes and use already existing ones when possible. An easy way to find which CSS classes exist is TODO.
# Implement the rest of the question type class. This is in questiontype.php. You need to consider
## Storing, retrieving, and deleting additional question options from the database when editing the question instance
## Storing, retrieving, and deleting additional question options and the session when the question is used in a quiz
## Displaying the question to the student
## Dealing with responses: grading responses, providing the correct responses, etc.
## Backing up and restoring a question instance.
## Importing and exporting a question instance.
# Make sure that the language file contains all the strings you refer to. Note that some of the strings you want may already be in the language files in Moodle core. If so, use the existing strings. An easy way to find the existing strings is to search the files in lang/en_utf8 (or whichever language), particularly lang/en_utf8/quiz.php .
# Write the help file for your question type, and any other help files you need.
# Write a set of unit tests for your question type.

All the places in the code where you need to do things are marked TODO, and there are comments right there giving more detailed instructions.

''Note that these comments are not complete or accurate yet. I have only just started implementing my own question type, and I will be filling in those comments and finishing this document as I go along.''[[User:Tim Hunt|Tim Hunt]] 11:46, 12 April 2007 (CDT)

===Import & Export Support===

You can provide import and export support by adding a function for (each) format type you wish to support. The naming format is '''import_from_format''' and '''export_to_format''', replacing format as appropriate (e.g., '''export_to_xml'''). Not all import/export plugins currently support this. See [[Import/export_for_questiontype_plugins]] for more information.

Note in particular that it is '''vital''' that your import format checks that the data passed really is for the same type of question as your plugin. In most cases this will simply be a matter of checking the question type (qtype) name in $data. This is done because the type name in the import format may not match the plugin name so '''all''' plugins will be polled to find one to handle the question.

===Language strings===

In lang/en_utf8/qtype_''myqtypeidentifier''.php you need to define at least the following strings:

<code php>
$string['addingQTYPEID'] = 'Adding a QTYPENAME question';
$string['editingQTYPEID'] = 'Editing a QTYPENAME question';
$string['QTYPEID'] = 'QTYPENAME';
$string['QTYPEIDsummary'] = 'One or two sentence summary of what this question type does.';
</code>

==Model Question Types==

If your question is similar to an existing question type (perhaps varying only in how it is displayed or how it is graded), it may be easier to adapt an existing question type rather than to start from the TEMPLATE question.

Be aware that backup/restore and import/export are handled differently for core question types than for contrib questions, so you will need to add backup/restore and import/export functions if you base your new question type on a core question type.

Even if your question is very different from existing question types, existing question types can provide good examples for various subtasks:

===Grading===

; essay : manual grading
; shortanswer : adaptive grading for a single response
; truefalse : grading a single response disallowing adaptive grading
; match : adaptive grading for multiple responses
; numerical : grading numerical answers with tolerance

===Backup/Restore and Import/Export===

Backup/restore and import/export are handled separately for core question types, so take a look at question types in contrib such as order or regexp.

==JavaScript and CSS required by your plugin==

If your plugin needs custom CSS of JavaScript, you can just add files called styles.css and/or script.js in the plugin folder, and they will be included automatically on any page of a quiz (or other place) where your question is attempted.

From Moodle 2.0 onwards, these files will also be include on the question/question.php page that shows the editing form for your question type.

If you have more complicated requirements, you can instead override the get_html_head_contributions and get_editing_head_contributions (2.0+) methods of the question type class.

Alternatively, if you really must, you can generate the CSS and JS using PHP code in by calling the files styles.php and script.php but that is really not recommended.

{{Moodle 2.1}}The get_editing_head_contributions method is deprecated, and no script.js file will be included anywhere (see [http://tracker.moodle.org/browse/MDL-28614 MDL 28614]). Use a module.js file instead and $PAGE->requires->js_init_call() in the definition_inner method of your editing form. See [https://docs.moodle.org/dev/JavaScript_guidelines JavaScript guidelines] for details. An example is the multianswer question type, which uses a slightly different method by calling js_init_call() in the question renderer.

==Configuration settings for your question type==

{{Moodle 2.0}}Sometimes you question type may need some configuration settings in the site admin area. Two examples of this would be the [http://moodle.org/mod/forum/discuss.php?d=102690 JUnit question type], which needs to know the path to <tt>java</tt> and <tt>javac</tt> on the server, and the [[Opaque|Opaque question type]], where you need to set up question engines to connect to.

To have admin settings for your question type, you just need to create a file settings.php inside your question type folder. In there, you need to create [[Admin_settings#Individual_settings|admin_settings objects]], and add them to the $settings object that will be in scope when settings.php is included. For example, the following code, if placed in question/type/sojunit/settings.php, would defined three text settings for the sojunit question type where the admin can type in the paths required to make this question type work.

<code php>
<?php
$settings->add(new admin_setting_configtext('qtype_sojunit/pathtojava',
get_string('pathtojava', 'qtype_sojunit'), get_string('configpathtojava', 'qtype_sojunit'),
'/usr/bin/java'));

$settings->add(new admin_setting_configtext('qtype_sojunit/pathtojavac',
get_string('pathtojavac', 'qtype_sojunit'), get_string('configpathtojavac', 'qtype_sojunit'),
'/usr/bin/javac'));

$settings->add(new admin_setting_configtext('qtype_sojunit/pathtojunit',
get_string('pathtojunit', 'qtype_sojunit'), get_string('configpathtojunit', 'qtype_sojunit'),
'/usr/share/java/junit.jar'));
?>
</code>

The question type code could then access these settings by doing

<code php>
$sojunitcfg = get_config('qtype_sojunit');
// Use $sojunitcfg->pathtojava, etc. in the processing.
</code>

==Testing==

How do you know that your new question type is working, and that you have done everything you need to? If you do all of the following tests, you can be fairly confident that you have done everything you need to:

# Create some new questions of your type, exercising each significantly different combination of options.
# Go back to the editing form for each question to make sure that the options were saved accurately and that you can change them and that the changes are then saved.
# Try typing invalid input into the editing form, and ensure it is rejected.
# Try each of your new questions in preview mode. Check that they correctly mark and give feedback for a range of correct and incorrect responses. Try using a range of browsers, particularly if you are using comples CSS or JavaScript.
# Add your questions to three quizzes, one in adaptive mode, one in non-adaptive mode, and one in non-adaptive mode with each attempt builds on last. Perhaps mix in some standard question types. Make one of the quizzes one question per page, and another with all the questions on the same page.
# Try those quizzes several times in preview mode, entering a range of correct and incorrect responses.
# Now log in as a student and take the quizzes for real.
# View all of the quiz reports, and ensure that they correctly display the information about your questions.
# Backup the course, restore it as a new course, and ensure that all your questions have been copied across accurately. Before doing this test, edit at least one of the questions and wherever HTML can be entered, insert a link to another part of the course, for example a resource. Ensure that after backup and restore, the link has been updated to point to the new URL of the restored resource.
# Export your questions from the original course to each of the import/export formats your support. Import these questions to a new question category, and ensure they have been copied accurately (within the limits to which your question type can be represented in each format).
# Check your question type against Accessibility guidelines, for example the [http://www.w3.org/WAI/intro/wcag.php Web Content Accessibility Guidelines].

==Debugging hints==

Here are some tips to help while trying to get your question type working:

* Watch the results of [[Question_database_structure#Following_what_happens_when_questions_are_attempted| this database query]] while attempting the question in a quiz, to see what is being stored in the database. This is a really useful way to find out what is going on in the code.

==When you have finished==

Consider checking your question type into the contrib area of the Moodle CVS server (if you have access, if not, request it or post your code as a zip file in the quiz forum) so that other people can share it.

Add your new question type to the [http://moodle.org/mod/data/view.php?id=6009 modules and plugins database].

[[Category:Quiz]]

lib/formslib.php Form Definition

2011-09-06T15:54:13Z

Fpirsch: /* disabledIf */

{{Formslib}}
== ''definition()'' ==

The definition of the elements to be included in the form, their 'types' (PARAM_*), helpbuttons included, etc. is all included in a function you must define in your class.

''definition()'' is used to define the elements in the form and '''this definition will be used for validating data submitted as well as for printing the form.''' For select and checkbox type elements only data that could have been selected will be allowed. And only data that corresponds to a form element in the definition will be accepted as submitted data.

The ''definition()'' should include all elements that are going to be used on form, some elements may be removed or tweaked later in ''definition_after_data()''. Please do not create conditional elements in ''definition()'', the definition() should not directly depend on the submitted data.

Note that the definition function is called when the form class is instantiated. There is no option to (say) manipulate data in the class (that may affect the rendering of the form) between instantiating the form and calling any other methods.

<code php>
require_once("$CFG->libdir/formslib.php");

class simplehtml_form extends moodleform {

function definition() {
global $CFG;

$mform =& $this->_form; // Don't forget the underscore!

$mform->addElement()... // Add elements to your form
...
} // Close the function
} // Close the class
</code>
===Passing parameters to the Form===

The constructor for ''moodleform'' allows a number of parameters including one (''$customdata'') to permit an array of arbitrary data to be passed to your form.

For example, you can pass the data "$email" and "$username" to the Form's class for use inside (say) the definition.
<code php>
...
$mform_simple = new simplehtml_form( null, array('email'=>$email, 'username'=>$username ) );
...
</code>
(the first parameter is $action, ''null'' will case the form action to be determined automatically)

Secondly, inside the form definition you can use those parameters to set the default values to some of the form's fields
<code php>
...
$mform->addElement('text', 'email', get_string('email'), 'maxlength="100" size="25" ');
$mform->setType('email', PARAM_NOTAGS);
$mform->addRule('email', get_string('missingemail'), 'required', null, 'server');
// Set default value by using a passed parameter
$mform->setDefault('email',$this->_customdata['email']);
...
</code>

==Use Fieldsets to group Form Elements==

You use code like this to open a fieldset with a ''legend''. <br />
('''Note''': Some themes turn off legends on admin setting pages by using CSS: <nowiki>#adminsettings legend {display:none;}</nowiki>.)

<code php>
$mform->addElement('header', 'nameforyourheaderelement', get_string('titleforlegened', 'modulename'));
</code>

You can't yet nest these visible fieldsets unfortunately. But in fact groups of elements are wrapped in invisible fieldsets.

You close a fieldset with moodle_form's closeHeaderBefore method. You tell closeHeaderBefore the element before you wish to end the fieldset. A fieldset is automatically closed if you open a new one. You need to use this code only if you want to close a fieldset and the subsequent form elements are not to be enclosed by a visible fieldset (they are still enclosed with an invisibe one with no legend) :

<code php>
$mform->closeHeaderBefore('buttonar');
</code>

==addElement==

Use the addElement method to add an element to a form. The first few arguments are always the same. The first param is the type of the element to add. The second is the elementname to use which is normally the html name of the element in the form. The third is often the text for the label for the element.

Some examples are below :
=== button ===

<code php>
$mform->addElement('button', 'intro', get_string("buttonlabel"));
</code>

A button element. If you want a submit or cancel button see 'submit' element.

=== checkbox ===

<code php>
$mform->addElement('checkbox', 'ratingtime', get_string('ratingtime', 'forum'));
</code>

This is a simple checkbox. The third parameter for this element is the label to display on the left side of the form. You can also supply a string as a fourth parameter to specify a label that will appear on the right of the element. Checkboxes and radio buttons can be grouped and have individual labels on their right.

You can have a 5th parameter $attributes, as on other elements.

==== advcheckbox ====
<code php>
$mform->addElement('advcheckbox', 'ratingtime', get_string('ratingtime', 'forum'), 'Label displayed after checkbox', array('group' => 1), array(0, 1));
</code>

Similar to the checkbox above, but with a couple of important improvements:

# The 5th parameter is a normal $attributes array, normally used to set HTML attributes for the <input> element. However, a special value of 'group' can be given, which will add a class name to the element, and enable its grouping for a [[lib/formslib.php_add_checkbox_controller|checkbox controller]]
#The 6th parameter is an array of values that will be associated with the checked/unchecked state of the checkbox. With a normal checkbox you cannot choose that value, and in fact an unchecked checkbox will not even be sent with the form data.

=== choosecoursefile ===
{{Moodle 1.9}}
<code php>
$mform->addElement('choosecoursefile', 'mediafile', get_string('mediafile', 'lesson'), array('courseid'=>$COURSE->id));
</code>

Choose a file from the course files area. The fourth option is a list of options for the element.

'''Note: This has been superceded by [[#filepicker|filepicker]] in Moodle 2.'''

<code php>
array('courseid' =>null, //if it is null (default then use global $COURSE
'height' =>500, // height of the popup window
'width' =>750, // width of the popup window
'options' =>'none'); //options string for the pop up window
//eg. 'menubar=0,location=0,scrollbars,resizable'
</code>

You can also pass an optional 5th parameter of attributes, as for other elements. The most useful way of using that is something like
<code php>array('maxlength' => 255, 'size' => 48)</code>
to control the maxlength / size of the text box (note size will default to 48 if not specified)

Finally, as this element is a group containing two elements (button + value), you can add validation rules by using the '''addGroupRule()''' method in this (complex) way:

<code php>$mform->addGroupRule('elementname', array('value' => array(array(list, of, rule, params, but, fieldname))));</code>

Where: '''"elementname"''' is the name of the choosecoursefile group element, '''"value"''' is the name of the text field within the group and the '''"list, of, addrule, params, but, fieldname"''' is exactly that, the list of fields in the normal addRule() function but ommiting the first one, the fieldname.

For example, the [http://cvs.moodle.org/moodle/mod/resource/type/file/resource.class.php?view=markup file/url resource type], uses one "choosecoursefile" element, and it controls the maximum length of the field (255) with this use of addGroupRule():

<code php>$mform->addGroupRule('reference', array('value' => array(array(get_string('maximumchars', '', 255), 'maxlength', 255, 'client'))));</code>

=== date_selector ===

<code php>
$mform->addElement('date_selector', 'assesstimefinish', get_string('to'));
</code>

This is a date selector. You can select a Day, Month and Year using a group of select boxes. The fourth param here is an array of options. The defaults for the options are :

<code php>
array(
'startyear' => 1970,
'stopyear' => 2020,
'timezone' => 99,
'applydst' => true,
'optional' => false
);
</code>

You can override these defaults by supplying an array as fourth param with one or more keys with a value to override the default. You can supply a fifth param of attributes here as well.

=== date_time_selector ===

<code php>
$mform->addElement('date_time_selector', 'assesstimestart', get_string('from'));
</code>

This is a group of select boxes to select a date (Day Month and Year) and time (Hour and Minute). When submitted, submitted data is processed and a timestamp is passed to $form->get_data(); the fourth param here is an array of options. The defaults for the options are:

<code php>
array(
'startyear' => 1970,
'stopyear' => 2020,
'timezone' => 99,
'applydst' => true,
'step' => 5
);
</code>

You can override these defaults by supplying an array as fourth param with one or more keys with a value to override the default. You can supply a fifth param of attributes here as well.

===duration===
{{Moodle 2.0}}

<code php>
$mform->addElement('duration', 'timelimit', get_string('timelimit', 'quiz'));
</code>
This field type lets the user input an interval of time. It comprises a text field, where you can type a number, and a dropdown for selecting a unit (days, hours, minutes or seconds). When submitted the value is converted to a number of seconds.

You can add a fourth parameter to give options. At the moment the only option supported is here is an array of options. The defaults for the options is:
<code php>array('optional' => true)</code>

You can also pass an optional 5th parameter of attributes, as for other elements. The most useful way of using that is something like
<code php>array('size' => 5)</code>
to control the size of the text box.

=== file ===

File upload input box with browse button. In the form definition type

<code php>
$mform->addElement('file', 'attachment', get_string('attachment', 'forum'));
</code>

after form submission and validation use

<code php>
if ($data = $mform->get_data()) {
...
$mform->save_files($destination_directory);
...
}
</code>

If there is no requirement to save the file, you can read the file contents directly into a string as follows...

<code php>
$mform->get_file_content('attachment');
</code>

If you need advanced settings such as required file, different max upload size or name of uploaded file

<code php>
$this->set_upload_manager(new upload_manager('attachment', true, false, $COURSE, false, 0, true, true, false));
$mform->addElement('file', 'attachment', get_string('attachment', 'forum'));
$mform->addRule('attachment', null, 'required');

</code>

<code php>
if ($data = $mform->get_data()) {
...
$mform->save_files($destination_directory);
$newfilename = $mform->get_new_filename();
...
}
</code>

When porting old code it is also possible to use the upload manager directly for processing of uploaded files.

Please note that if using set_upload_manager() it must be before addElement('file',..).

{{Moodle 2.0}}
File uploading was rewritten in 2.0. Please see inline docs for now. This page will be updated when the new API stabilises.

===filepicker===
{{Moodle 2.0}}
General replacement of ''file'' element.

<code php>
$mform->addElement('filepicker', 'userfile', get_string('file'), null, array('maxbytes' => $maxbytes, 'accepted_types' => '*'));
</code>
See also [[Using the File API in Moodle forms]]

=== hidden ===
<code php>
$mform->addElement('hidden', 'reply', 'yes');
</code>

A hidden element. Set the element name (in this case '''reply''') to the stated value (in this case '''yes''').

=== html ===
You can add arbitrary HTML to your Moodle form:

<code php>
$mform->addElement('html', '<div class="qheader">');
</code>

See [http://moodle.org/mod/forum/discuss.php?d=126935 "Question: Can I put a moodleform inside a table td?"] for a concrete example.

=== htmleditor & format ===

<code php>
$mform->addElement('htmleditor', 'text', get_string('choicetext', 'choice'));
$mform->setType('text', PARAM_RAW);
$mform->addRule('text', null, 'required', null, 'client');

$mform->addElement('format', 'format', get_string('format'));
</code>

You can supply a fourth param to htmleditor of an array of options :

<code php>

array(
'canUseHtmlEditor'=>'detect',
'rows' => 10,
'cols' => 65,
'width' => 0,
'height'=> 0,
'course'=> 0,
);
//options same as print_textarea params
//use rows and cols options to control htmleditor size.
</code>

===modgrade===
<pre>
$mform->addElement('modgrade', 'scale', get_string('grade'), false);
</pre>
This is a custom element for selecting a grade for any activity module. The fourth argument is whether to include an option for no grade which has a value 0. This select box does include scales. The default is true, include no grade option.

A helpbutton is automatically added.

===password===
<pre>
$mform->addElement('password', 'password', get_string('label'), $attributes);
</pre>

A password element. Fourth param is an array or string of attributes.

===passwordunmask===
{{Moodle 1.9}}
<pre>
$mform->addElement('passwordunmask', 'password', get_string('label'), $attributes);
</pre>

A password element with option to show the password in plaintext. Fourth param is an array or string of attributes.

=== radio ===

<code php>
$radioarray=array();
$radioarray[] = &MoodleQuickForm::createElement('radio', 'yesno', '', get_string('yes'), 1, $attributes);
$radioarray[] = &MoodleQuickForm::createElement('radio', 'yesno', '', get_string('no'), 0, $attributes);
$mform->addGroup($radioarray, 'radioar', '', array(' '), false);
</code>

Second param names the radio button and should be the same for each button in the group in order to toggle correctly. Third param would be the label for the form element but is generally ignored as this element will always be in a group which has it's own label. Fourth param is a string, a label to be displayed on the right of the element. The fifth is the value for this radio button. $attributes can be a string or an array of attributes.

It is possible to add help to individual radio buttons but this requires a custom template to be defined for the group elements. See MDL-15571.

==== setDefault ====

To set the default for a radio button group as above use the following :

<code php>
$mform->setDefault('yesno', 0);
</code>

This would make the default 'no'.

===select===
<pre>
$mform->addElement('select', 'type', get_string('forumtype', 'forum'), $FORUM_TYPES, $attributes);
</pre>

The fourth param for this element is an array of options for the select box. The keys are the values for the option and the value of the array is the text for the option. The fifth param $attributes is optional, see text element for description of attributes param.

It is also possible to create a select with certain options disabled, using [http://stackoverflow.com/questions/2138089/how-can-i-use-quickform-to-add-disabled-select-options/2150275#2150275 this technique].

====multi-select====
<pre>
$select = &$mform->addElement('select', 'colors', get_string('colors'), array('red', 'blue', 'green'), $attributes);
$select->setMultiple(true);
</pre>

=====setSelected=====

To set the default selected item in a select element, you should use the 'setSelected' function, as follows:
<code>
$select = &$mform->addElement('select', 'colors', get_string('colors'), array('red', 'blue', 'green'), $attributes);
$select->setSelected('blue');
</code>
However you probably don't want to do this. Instead you probably want to use setDefault, or set it using the form's setData method.

===selectyesno===
<pre>
$mform->addElement('selectyesno', 'maxbytes', get_string('maxattachmentsize', 'forum'));
</pre>

If you want a yes / no select box this one automatically translates itself and has value 1 for yes and 0 for no.

===static===
<pre>
$mform->addElement('static', 'description', get_string('description', 'exercise'),
get_string('descriptionofexercise', 'exercise', $COURSE->students));

</pre>

This is a static element. It should be used with care if it is used to display a static piece of text with a label. The third param is the label and the fourth is the static text itself.

===submit, reset and cancel===

<pre>
//normally you use add_action_buttons instead of this code
$buttonarray=array();
$buttonarray[] = &$mform->createElement('submit', 'submitbutton', get_string('savechanges'));
$buttonarray[] = &$mform->createElement('reset', 'resetbutton', get_string('revert'));
$buttonarray[] = &$mform->createElement('cancel');
$mform->addGroup($buttonarray, 'buttonar', '', array(' '), false);
$mform->closeHeaderBefore('buttonar');
</pre>

A 'Submit' type element is a submit type form element which will submit the form. A 'Reset' will not submit the form but will reset any changes the user has made to form contents. A 'Cancel' element cancels form submission. You need to have a branch in your code before you check for get_data() to check if submission has been cancelled with is_cancelled(); See the example on the usage page.

You should name your submit and reset buttons 'submitbutton' and 'resetbutton' or something similar (not 'submit' and 'reset'). This avoids problems in JavaScript of collisions between form element names and names of JavaScript methods of the form object.

====add_action_buttons($cancel = true, $submitlabel=null);====

You will normally use this helper function which is a method of moodleform to add all the 'action' buttons to the end of your form. A boolean parameter allow you to specify whether to include a cancel button and specify the label for your submit button (pass the result of get_string). Default for the submit button label is get_string('savechanges'). Note the '''$this''' not '''$mform'''

<code>
$this->add_action_buttons();
</code>

===text===

<pre>
$mform->addElement('text', 'name', get_string('forumname', 'forum'), $attributes);
</pre>
For a simple text element. Your fourth parameter here can be a string or array of attributes for the text element. The following are equivalent :
<pre>
$attributes='size="20"';
$attributes=array('size'=>'20');
</pre>

Generally you are encouraged to use CSS instead of using attributes for styling.

A format element can be used as a format select box. It will be non-selectable if you're using an html editor.

The third param for this element is $useHtmlEditor and it defaults to null in which case an html editor is used if the browser and user profile support it.

===textarea===

<pre>
$mform->addElement('textarea', 'introduction', get_string("introtext", "survey"), 'wrap="virtual" rows="20" cols="50"');
</pre>

A textarea element. If you want an htmleditor use htmleditor element. Fourth element here is a string or array of attributes.

===recaptcha===
{{Moodle 1.9}}
<pre>
$mform->addElement('recaptcha', 'recaptcha_field_name', $attributes);
</pre>

Use this recaptcha element to reduce the spam risk in your forms. Third element here is a string or array of attributes. Take care to get an API key from http://recaptcha.net/api/getkey before using this element.

To check whether recaptcha is enabled at site level use:
<pre>
if (!empty($CFG->recaptchapublickey) && !empty($CFG->recaptchaprivatekey)) {
//recaptcha is enabled
}
</pre>

===tags===
{{Moodle 2.0}}

<pre>
$mform->addElement('tags', 'field_name', $lable, $options, $attributes);
</pre>

Used for editing a list of tags, for example on a blog post.

There is only one option available, 'display', which should be set to one of the contstants MoodleQuickForm_tags::ONLYOFFICIAL, NOOFFICIAL or DEFAULTUI. This controls whether the official tags are listed for easy selection, or a text area where arbitrary tags may be typed, or both. The default is both.

The value should be set/returned as an array of tags.

==addGroup==

A 'group' in formslib is just a group of elements that will have a label and will be included on one line.

For example typical code to include a submit and cancel button on the same line :

<pre>
$buttonarray=array();
$buttonarray[] =& $mform->createElement('submit', 'submitbutton', get_string('savechanges'));
$buttonarray[] =& $mform->createElement('submit', 'cancel', get_string('cancel'));
$mform->addGroup($buttonarray, 'buttonar', '', array(' '), false);
</pre>

You use the same arguments for createElement as you do for addElement. Any label for the element in the third argument is normally ignored (but not in the case of the submit buttons above where the third argument is not for a label but is the text for the button).

Here's a bad example (don't do this for real, use the 'optional' => true option of the date element): putting a date_selector (which is itself a group of elements) and a checkbox on the same line, note that you can disable every element in the group using the group name 'availablefromgroup' but it doesn't disable the controlling element the 'availablefromenabled' checkbox:

<pre>
$availablefromgroup=array();
$availablefromgroup[] =& $mform->createElement('date_selector', 'availablefrom', '');
$availablefromgroup[] =& $mform->createElement('checkbox', 'availablefromenabled', '', get_string('enable'));
$mform->addGroup($availablefromgroup, 'availablefromgroup', get_string('availablefromdate', 'data'), ' ', false);
$mform->disabledIf('availablefromgroup', 'availablefromenabled');

</pre>

==addRule==
<pre>
$mform->addRule('elementname', get_string('error'), 'rule type', 'extraruledata', 'server'(default), false, false);
</pre>

The first param(element) is an element name and second(message) is the error message that will be displayed to the user.
The third parameter(type) is the type of rule. The fourth param(format) is used for extra data needed with some rules such as minlength and regex. The fifth parameter(validation) validates input data on server or client side, if validation is done on client side then it will be checked on the server side as well.

<pre>
* @param string $element Form element name
* @param string $message Message to display for invalid data
* @param string $type Rule type, use getRegisteredRules() to get types
* @param string $format (optional)Required for extra rule data
* @param string $validation (optional)Where to perform validation: "server", "client"
* @param boolean $reset Client-side validation: reset the form element to its original value if there is an error?
* @param boolean $force Force the rule to be applied, even if the target form element does not exist
</pre>

'''Common Rule Types'''
* required
* maxlength
* minlength
* rangelength
* email
* regex
* lettersonly
* alphanumeric
* numeric
* nopunctuation
* nonzero
* callback
* compare

===Server side and Client side===
In case you use the ''Client side'' validation option, you can mainly check for an empty or not input field. unless you write some ''Client side'' code which will probably be JavaScript functions to verify the data inside the input fields before it is submitted to the server. It could save some time if those functions are short, simple and quick to compute.
In case you need a more complex validation checks which relay on Moodle's internal PHP libraries (or other/external PHP libraries) you better use the ''Server side'' validation checks. Where you can query the DB, write complex PHP validation functions and much much more, that are not available (easily) when using JavaScript on the client's side.

==setHelpButton==
{{Moodle 1.9}}

<pre>
$mform->setHelpButton('lessondefault', array('lessondefault', get_string('lessondefault', 'lesson'), 'lesson'));
</pre>
First param is an elementname and the second param is an array of params that are passed to helpbutton in weblib.php. Params are :

<pre>
* @param string $page The keyword that defines a help page
* @param string $title The title of links, rollover tips, alt tags etc
* 'Help with' (or the language equivalent) will be prefixed and '...' will be stripped.
* @param string $module Which module is the page defined in
* @param mixed $image Use a help image for the link? (true/false/"both")
* @param boolean $linktext If true, display the title next to the help icon.
* @param string $text If defined then this text is used in the page, and
* the $page variable is ignored.
* @param boolean $return If true then the output is returned as a string, if false it is printed to the current page.
* @param string $imagetext The full text for the helpbutton icon. If empty use default help.gif
</pre>
Make sure you don't set boolean $return to false.

You need to do use this method after addElement();

==addHelpButton==
{{Moodle 2.0}}

<pre>
$mform->addHelpButton('api_key_field', 'api_key', 'block_extsearch');
</pre>

In Moodle 2.0 the "setHelpButton" method has been deprecated in favor of the "addHelpButton" method, which has a simplified interface and uses $OUTPUT->help_icon() on the back end. The following parameters are expected:

* @param $elementname The name of the form element to add the help button for
* @param $identifier The identifier for the help string and its title (see below)
* @param $component The component name to look for the help string in

Unlike in Moodle 1.9, it is no longer necessary to put your help pages in separate HTML files. Instead, the function looks for two strings:

1. get_string($identifier, $component): The title of the help page
2. get_string("{$identifier}_help", $component): The content of the help page

So you will need to have '''$identifier''' and '''{$identifier}_help''' defined in order for the help button to be created properly. For example the multiple choice question editing form has a button for shuffling the answers.
<pre>
$mform->addHelpButton('shuffleanswers', 'shuffleanswers', 'qtype_multichoice');
</pre>
and so the language file includes the strings
<pre>
$string['shuffleanswers'] = 'Shuffle the choices?';
$string['shuffleanswers_help'] = 'If enabled,.....
</pre>
==setDefault==

<pre>
$mform->addElement('select', 'grade', get_string('gradeforsubmission', 'exercise'), $grades);
$mform->setHelpButton('grade', array('grade', get_string('gradeforsubmission', 'exercise'), 'exercise'));
$mform->setDefault('grade', 100);
</pre>

Set the default of the form value with setDefault($elementname, $value); where elementname is the elementname whose default you want to set and $value is the default to set. We set the defaults for the form in definition(). This default is what is used if no data is loaded into the form with set_data(); eg. on display of the form for an 'add' rather than 'update' function.

==disabledIf==

For any element or groups of element in a form you can conditionally disable the group or individual element depending on conditions.

You can use $mform->disabledIf($elementName, $dependentOn, $condition = 'notchecked', $value='1')

* elementname can be a group. If you specify a group all elements in the group will be disabled (if dependentOn is in elementname group that is ignored and not disabled). These are the element names you've used as the second argument in addElement or addGroup.
* dependentOn is the actual name of the element as it will appear in html. This can be different to the name used in addGroup particularly but also addElement where you're adding a complex element like a date_selector. Check the html of your page. You typically make the depedentOn a checkbox or select box.
* $condition will be 'notchecked', 'checked', 'noitemselected', 'eq' or, if it is anything else, we test for 'neq'.
** If $condition is 'eq' or 'neq' then we check the value of the dependentOn field and check for equality (==) or nonequality (!=) in js
** If $condition is 'checked' or 'notchecked' then we check to see if a checkbox is checked or not.
** If $condition is 'noitemselected' then we check to see whether nothing is selected in a dropdown list.

Examples:
// Disable my control unless a checkbox is checked.
$mform->disabledIf('mycontrol', 'somecheckbox');

// Disable my control if a checkbox '''is''' checked.
$mform->disabledIf('mycontrol', 'somecheckbox', 'checked');

// Disable my control unless a dropdown has value 42.
$mform->disabledIf('mycontrol', 'someselect', 'eq', 42);

The possible choices here are in the dependency manager in lib/form/form.js.

==setType==

PARAM_* types are used to specify how a submitted variable should be cleaned. These should be used for get parameters such as id, course etc. which are used to load a page and also with setType(); method. Every form element should have a type specified except select, radio box and checkbox elements, these elements do a good job of cleaning themselves (only specified options are allowed as user input).

===Most Commonly Used PARAM_* Types===

These are the most commonly used PARAM_* types and their proper uses. More types can be seen in moodlelib.php starting around line 100.

* PARAM_CLEAN is deprecated and you should try to use a more specific type.
* PARAM_TEXT should be used for cleaning data that is expected to be plain text. It will strip all html tags. But will still let tags for multilang support through.
* PARAM_NOTAGS should be used for cleaning data that is expected to be plain text. It will strip *all* html type tags. It will still *not* let tags for multilang support through. This should be used for instance for email addresses where no multilang support is appropriate.
* PARAM_RAW means no cleaning whatsoever, it is used mostly for data from the html editor. Data from the editor is later cleaned before display using format_text() function. PARAM_RAW can also be used for data that is validated by some other way or printed by p() or s().
* PARAM_INT should be used for integers.
* PARAM_ACTION is an alias of PARAM_ALPHA and is used for hidden fields specifying form actions.

==References==

* [http://www.midnighthax.com/quickform.php PEAR HTML QuickForm Getting Started Guide] by Keith Edmunds of Midnighthax.com
* [http://pear.php.net/manual/en/package.html.html-quickform.php PEAR::HTML_QuickForm manual]

[[Category:Formslib]]

If you have problems creating php forms you may get them with form builder http://phpforms.net/tutorial/html-basics/form-builder.html

lib/formslib.php Form Definition

2011-09-06T15:32:44Z

Fpirsch: /* disabledIf */

{{Formslib}}
== ''definition()'' ==

The definition of the elements to be included in the form, their 'types' (PARAM_*), helpbuttons included, etc. is all included in a function you must define in your class.

''definition()'' is used to define the elements in the form and '''this definition will be used for validating data submitted as well as for printing the form.''' For select and checkbox type elements only data that could have been selected will be allowed. And only data that corresponds to a form element in the definition will be accepted as submitted data.

The ''definition()'' should include all elements that are going to be used on form, some elements may be removed or tweaked later in ''definition_after_data()''. Please do not create conditional elements in ''definition()'', the definition() should not directly depend on the submitted data.

Note that the definition function is called when the form class is instantiated. There is no option to (say) manipulate data in the class (that may affect the rendering of the form) between instantiating the form and calling any other methods.

<code php>
require_once("$CFG->libdir/formslib.php");

class simplehtml_form extends moodleform {

function definition() {
global $CFG;

$mform =& $this->_form; // Don't forget the underscore!

$mform->addElement()... // Add elements to your form
...
} // Close the function
} // Close the class
</code>
===Passing parameters to the Form===

The constructor for ''moodleform'' allows a number of parameters including one (''$customdata'') to permit an array of arbitrary data to be passed to your form.

For example, you can pass the data "$email" and "$username" to the Form's class for use inside (say) the definition.
<code php>
...
$mform_simple = new simplehtml_form( null, array('email'=>$email, 'username'=>$username ) );
...
</code>
(the first parameter is $action, ''null'' will case the form action to be determined automatically)

Secondly, inside the form definition you can use those parameters to set the default values to some of the form's fields
<code php>
...
$mform->addElement('text', 'email', get_string('email'), 'maxlength="100" size="25" ');
$mform->setType('email', PARAM_NOTAGS);
$mform->addRule('email', get_string('missingemail'), 'required', null, 'server');
// Set default value by using a passed parameter
$mform->setDefault('email',$this->_customdata['email']);
...
</code>

==Use Fieldsets to group Form Elements==

You use code like this to open a fieldset with a ''legend''. <br />
('''Note''': Some themes turn off legends on admin setting pages by using CSS: <nowiki>#adminsettings legend {display:none;}</nowiki>.)

<code php>
$mform->addElement('header', 'nameforyourheaderelement', get_string('titleforlegened', 'modulename'));
</code>

You can't yet nest these visible fieldsets unfortunately. But in fact groups of elements are wrapped in invisible fieldsets.

You close a fieldset with moodle_form's closeHeaderBefore method. You tell closeHeaderBefore the element before you wish to end the fieldset. A fieldset is automatically closed if you open a new one. You need to use this code only if you want to close a fieldset and the subsequent form elements are not to be enclosed by a visible fieldset (they are still enclosed with an invisibe one with no legend) :

<code php>
$mform->closeHeaderBefore('buttonar');
</code>

==addElement==

Use the addElement method to add an element to a form. The first few arguments are always the same. The first param is the type of the element to add. The second is the elementname to use which is normally the html name of the element in the form. The third is often the text for the label for the element.

Some examples are below :
=== button ===

<code php>
$mform->addElement('button', 'intro', get_string("buttonlabel"));
</code>

A button element. If you want a submit or cancel button see 'submit' element.

=== checkbox ===

<code php>
$mform->addElement('checkbox', 'ratingtime', get_string('ratingtime', 'forum'));
</code>

This is a simple checkbox. The third parameter for this element is the label to display on the left side of the form. You can also supply a string as a fourth parameter to specify a label that will appear on the right of the element. Checkboxes and radio buttons can be grouped and have individual labels on their right.

You can have a 5th parameter $attributes, as on other elements.

==== advcheckbox ====
<code php>
$mform->addElement('advcheckbox', 'ratingtime', get_string('ratingtime', 'forum'), 'Label displayed after checkbox', array('group' => 1), array(0, 1));
</code>

Similar to the checkbox above, but with a couple of important improvements:

# The 5th parameter is a normal $attributes array, normally used to set HTML attributes for the <input> element. However, a special value of 'group' can be given, which will add a class name to the element, and enable its grouping for a [[lib/formslib.php_add_checkbox_controller|checkbox controller]]
#The 6th parameter is an array of values that will be associated with the checked/unchecked state of the checkbox. With a normal checkbox you cannot choose that value, and in fact an unchecked checkbox will not even be sent with the form data.

=== choosecoursefile ===
{{Moodle 1.9}}
<code php>
$mform->addElement('choosecoursefile', 'mediafile', get_string('mediafile', 'lesson'), array('courseid'=>$COURSE->id));
</code>

Choose a file from the course files area. The fourth option is a list of options for the element.

'''Note: This has been superceded by [[#filepicker|filepicker]] in Moodle 2.'''

<code php>
array('courseid' =>null, //if it is null (default then use global $COURSE
'height' =>500, // height of the popup window
'width' =>750, // width of the popup window
'options' =>'none'); //options string for the pop up window
//eg. 'menubar=0,location=0,scrollbars,resizable'
</code>

You can also pass an optional 5th parameter of attributes, as for other elements. The most useful way of using that is something like
<code php>array('maxlength' => 255, 'size' => 48)</code>
to control the maxlength / size of the text box (note size will default to 48 if not specified)

Finally, as this element is a group containing two elements (button + value), you can add validation rules by using the '''addGroupRule()''' method in this (complex) way:

<code php>$mform->addGroupRule('elementname', array('value' => array(array(list, of, rule, params, but, fieldname))));</code>

Where: '''"elementname"''' is the name of the choosecoursefile group element, '''"value"''' is the name of the text field within the group and the '''"list, of, addrule, params, but, fieldname"''' is exactly that, the list of fields in the normal addRule() function but ommiting the first one, the fieldname.

For example, the [http://cvs.moodle.org/moodle/mod/resource/type/file/resource.class.php?view=markup file/url resource type], uses one "choosecoursefile" element, and it controls the maximum length of the field (255) with this use of addGroupRule():

<code php>$mform->addGroupRule('reference', array('value' => array(array(get_string('maximumchars', '', 255), 'maxlength', 255, 'client'))));</code>

=== date_selector ===

<code php>
$mform->addElement('date_selector', 'assesstimefinish', get_string('to'));
</code>

This is a date selector. You can select a Day, Month and Year using a group of select boxes. The fourth param here is an array of options. The defaults for the options are :

<code php>
array(
'startyear' => 1970,
'stopyear' => 2020,
'timezone' => 99,
'applydst' => true,
'optional' => false
);
</code>

You can override these defaults by supplying an array as fourth param with one or more keys with a value to override the default. You can supply a fifth param of attributes here as well.

=== date_time_selector ===

<code php>
$mform->addElement('date_time_selector', 'assesstimestart', get_string('from'));
</code>

This is a group of select boxes to select a date (Day Month and Year) and time (Hour and Minute). When submitted, submitted data is processed and a timestamp is passed to $form->get_data(); the fourth param here is an array of options. The defaults for the options are:

<code php>
array(
'startyear' => 1970,
'stopyear' => 2020,
'timezone' => 99,
'applydst' => true,
'step' => 5
);
</code>

You can override these defaults by supplying an array as fourth param with one or more keys with a value to override the default. You can supply a fifth param of attributes here as well.

===duration===
{{Moodle 2.0}}

<code php>
$mform->addElement('duration', 'timelimit', get_string('timelimit', 'quiz'));
</code>
This field type lets the user input an interval of time. It comprises a text field, where you can type a number, and a dropdown for selecting a unit (days, hours, minutes or seconds). When submitted the value is converted to a number of seconds.

You can add a fourth parameter to give options. At the moment the only option supported is here is an array of options. The defaults for the options is:
<code php>array('optional' => true)</code>

You can also pass an optional 5th parameter of attributes, as for other elements. The most useful way of using that is something like
<code php>array('size' => 5)</code>
to control the size of the text box.

=== file ===

File upload input box with browse button. In the form definition type

<code php>
$mform->addElement('file', 'attachment', get_string('attachment', 'forum'));
</code>

after form submission and validation use

<code php>
if ($data = $mform->get_data()) {
...
$mform->save_files($destination_directory);
...
}
</code>

If there is no requirement to save the file, you can read the file contents directly into a string as follows...

<code php>
$mform->get_file_content('attachment');
</code>

If you need advanced settings such as required file, different max upload size or name of uploaded file

<code php>
$this->set_upload_manager(new upload_manager('attachment', true, false, $COURSE, false, 0, true, true, false));
$mform->addElement('file', 'attachment', get_string('attachment', 'forum'));
$mform->addRule('attachment', null, 'required');

</code>

<code php>
if ($data = $mform->get_data()) {
...
$mform->save_files($destination_directory);
$newfilename = $mform->get_new_filename();
...
}
</code>

When porting old code it is also possible to use the upload manager directly for processing of uploaded files.

Please note that if using set_upload_manager() it must be before addElement('file',..).

{{Moodle 2.0}}
File uploading was rewritten in 2.0. Please see inline docs for now. This page will be updated when the new API stabilises.

===filepicker===
{{Moodle 2.0}}
General replacement of ''file'' element.

<code php>
$mform->addElement('filepicker', 'userfile', get_string('file'), null, array('maxbytes' => $maxbytes, 'accepted_types' => '*'));
</code>
See also [[Using the File API in Moodle forms]]

=== hidden ===
<code php>
$mform->addElement('hidden', 'reply', 'yes');
</code>

A hidden element. Set the element name (in this case '''reply''') to the stated value (in this case '''yes''').

=== html ===
You can add arbitrary HTML to your Moodle form:

<code php>
$mform->addElement('html', '<div class="qheader">');
</code>

See [http://moodle.org/mod/forum/discuss.php?d=126935 "Question: Can I put a moodleform inside a table td?"] for a concrete example.

=== htmleditor & format ===

<code php>
$mform->addElement('htmleditor', 'text', get_string('choicetext', 'choice'));
$mform->setType('text', PARAM_RAW);
$mform->addRule('text', null, 'required', null, 'client');

$mform->addElement('format', 'format', get_string('format'));
</code>

You can supply a fourth param to htmleditor of an array of options :

<code php>

array(
'canUseHtmlEditor'=>'detect',
'rows' => 10,
'cols' => 65,
'width' => 0,
'height'=> 0,
'course'=> 0,
);
//options same as print_textarea params
//use rows and cols options to control htmleditor size.
</code>

===modgrade===
<pre>
$mform->addElement('modgrade', 'scale', get_string('grade'), false);
</pre>
This is a custom element for selecting a grade for any activity module. The fourth argument is whether to include an option for no grade which has a value 0. This select box does include scales. The default is true, include no grade option.

A helpbutton is automatically added.

===password===
<pre>
$mform->addElement('password', 'password', get_string('label'), $attributes);
</pre>

A password element. Fourth param is an array or string of attributes.

===passwordunmask===
{{Moodle 1.9}}
<pre>
$mform->addElement('passwordunmask', 'password', get_string('label'), $attributes);
</pre>

A password element with option to show the password in plaintext. Fourth param is an array or string of attributes.

=== radio ===

<code php>
$radioarray=array();
$radioarray[] = &MoodleQuickForm::createElement('radio', 'yesno', '', get_string('yes'), 1, $attributes);
$radioarray[] = &MoodleQuickForm::createElement('radio', 'yesno', '', get_string('no'), 0, $attributes);
$mform->addGroup($radioarray, 'radioar', '', array(' '), false);
</code>

Second param names the radio button and should be the same for each button in the group in order to toggle correctly. Third param would be the label for the form element but is generally ignored as this element will always be in a group which has it's own label. Fourth param is a string, a label to be displayed on the right of the element. The fifth is the value for this radio button. $attributes can be a string or an array of attributes.

It is possible to add help to individual radio buttons but this requires a custom template to be defined for the group elements. See MDL-15571.

==== setDefault ====

To set the default for a radio button group as above use the following :

<code php>
$mform->setDefault('yesno', 0);
</code>

This would make the default 'no'.

===select===
<pre>
$mform->addElement('select', 'type', get_string('forumtype', 'forum'), $FORUM_TYPES, $attributes);
</pre>

The fourth param for this element is an array of options for the select box. The keys are the values for the option and the value of the array is the text for the option. The fifth param $attributes is optional, see text element for description of attributes param.

It is also possible to create a select with certain options disabled, using [http://stackoverflow.com/questions/2138089/how-can-i-use-quickform-to-add-disabled-select-options/2150275#2150275 this technique].

====multi-select====
<pre>
$select = &$mform->addElement('select', 'colors', get_string('colors'), array('red', 'blue', 'green'), $attributes);
$select->setMultiple(true);
</pre>

=====setSelected=====

To set the default selected item in a select element, you should use the 'setSelected' function, as follows:
<code>
$select = &$mform->addElement('select', 'colors', get_string('colors'), array('red', 'blue', 'green'), $attributes);
$select->setSelected('blue');
</code>
However you probably don't want to do this. Instead you probably want to use setDefault, or set it using the form's setData method.

===selectyesno===
<pre>
$mform->addElement('selectyesno', 'maxbytes', get_string('maxattachmentsize', 'forum'));
</pre>

If you want a yes / no select box this one automatically translates itself and has value 1 for yes and 0 for no.

===static===
<pre>
$mform->addElement('static', 'description', get_string('description', 'exercise'),
get_string('descriptionofexercise', 'exercise', $COURSE->students));

</pre>

This is a static element. It should be used with care if it is used to display a static piece of text with a label. The third param is the label and the fourth is the static text itself.

===submit, reset and cancel===

<pre>
//normally you use add_action_buttons instead of this code
$buttonarray=array();
$buttonarray[] = &$mform->createElement('submit', 'submitbutton', get_string('savechanges'));
$buttonarray[] = &$mform->createElement('reset', 'resetbutton', get_string('revert'));
$buttonarray[] = &$mform->createElement('cancel');
$mform->addGroup($buttonarray, 'buttonar', '', array(' '), false);
$mform->closeHeaderBefore('buttonar');
</pre>

A 'Submit' type element is a submit type form element which will submit the form. A 'Reset' will not submit the form but will reset any changes the user has made to form contents. A 'Cancel' element cancels form submission. You need to have a branch in your code before you check for get_data() to check if submission has been cancelled with is_cancelled(); See the example on the usage page.

You should name your submit and reset buttons 'submitbutton' and 'resetbutton' or something similar (not 'submit' and 'reset'). This avoids problems in JavaScript of collisions between form element names and names of JavaScript methods of the form object.

====add_action_buttons($cancel = true, $submitlabel=null);====

You will normally use this helper function which is a method of moodleform to add all the 'action' buttons to the end of your form. A boolean parameter allow you to specify whether to include a cancel button and specify the label for your submit button (pass the result of get_string). Default for the submit button label is get_string('savechanges'). Note the '''$this''' not '''$mform'''

<code>
$this->add_action_buttons();
</code>

===text===

<pre>
$mform->addElement('text', 'name', get_string('forumname', 'forum'), $attributes);
</pre>
For a simple text element. Your fourth parameter here can be a string or array of attributes for the text element. The following are equivalent :
<pre>
$attributes='size="20"';
$attributes=array('size'=>'20');
</pre>

Generally you are encouraged to use CSS instead of using attributes for styling.

A format element can be used as a format select box. It will be non-selectable if you're using an html editor.

The third param for this element is $useHtmlEditor and it defaults to null in which case an html editor is used if the browser and user profile support it.

===textarea===

<pre>
$mform->addElement('textarea', 'introduction', get_string("introtext", "survey"), 'wrap="virtual" rows="20" cols="50"');
</pre>

A textarea element. If you want an htmleditor use htmleditor element. Fourth element here is a string or array of attributes.

===recaptcha===
{{Moodle 1.9}}
<pre>
$mform->addElement('recaptcha', 'recaptcha_field_name', $attributes);
</pre>

Use this recaptcha element to reduce the spam risk in your forms. Third element here is a string or array of attributes. Take care to get an API key from http://recaptcha.net/api/getkey before using this element.

To check whether recaptcha is enabled at site level use:
<pre>
if (!empty($CFG->recaptchapublickey) && !empty($CFG->recaptchaprivatekey)) {
//recaptcha is enabled
}
</pre>

===tags===
{{Moodle 2.0}}

<pre>
$mform->addElement('tags', 'field_name', $lable, $options, $attributes);
</pre>

Used for editing a list of tags, for example on a blog post.

There is only one option available, 'display', which should be set to one of the contstants MoodleQuickForm_tags::ONLYOFFICIAL, NOOFFICIAL or DEFAULTUI. This controls whether the official tags are listed for easy selection, or a text area where arbitrary tags may be typed, or both. The default is both.

The value should be set/returned as an array of tags.

==addGroup==

A 'group' in formslib is just a group of elements that will have a label and will be included on one line.

For example typical code to include a submit and cancel button on the same line :

<pre>
$buttonarray=array();
$buttonarray[] =& $mform->createElement('submit', 'submitbutton', get_string('savechanges'));
$buttonarray[] =& $mform->createElement('submit', 'cancel', get_string('cancel'));
$mform->addGroup($buttonarray, 'buttonar', '', array(' '), false);
</pre>

You use the same arguments for createElement as you do for addElement. Any label for the element in the third argument is normally ignored (but not in the case of the submit buttons above where the third argument is not for a label but is the text for the button).

Here's a bad example (don't do this for real, use the 'optional' => true option of the date element): putting a date_selector (which is itself a group of elements) and a checkbox on the same line, note that you can disable every element in the group using the group name 'availablefromgroup' but it doesn't disable the controlling element the 'availablefromenabled' checkbox:

<pre>
$availablefromgroup=array();
$availablefromgroup[] =& $mform->createElement('date_selector', 'availablefrom', '');
$availablefromgroup[] =& $mform->createElement('checkbox', 'availablefromenabled', '', get_string('enable'));
$mform->addGroup($availablefromgroup, 'availablefromgroup', get_string('availablefromdate', 'data'), ' ', false);
$mform->disabledIf('availablefromgroup', 'availablefromenabled');

</pre>

==addRule==
<pre>
$mform->addRule('elementname', get_string('error'), 'rule type', 'extraruledata', 'server'(default), false, false);
</pre>

The first param(element) is an element name and second(message) is the error message that will be displayed to the user.
The third parameter(type) is the type of rule. The fourth param(format) is used for extra data needed with some rules such as minlength and regex. The fifth parameter(validation) validates input data on server or client side, if validation is done on client side then it will be checked on the server side as well.

<pre>
* @param string $element Form element name
* @param string $message Message to display for invalid data
* @param string $type Rule type, use getRegisteredRules() to get types
* @param string $format (optional)Required for extra rule data
* @param string $validation (optional)Where to perform validation: "server", "client"
* @param boolean $reset Client-side validation: reset the form element to its original value if there is an error?
* @param boolean $force Force the rule to be applied, even if the target form element does not exist
</pre>

'''Common Rule Types'''
* required
* maxlength
* minlength
* rangelength
* email
* regex
* lettersonly
* alphanumeric
* numeric
* nopunctuation
* nonzero
* callback
* compare

===Server side and Client side===
In case you use the ''Client side'' validation option, you can mainly check for an empty or not input field. unless you write some ''Client side'' code which will probably be JavaScript functions to verify the data inside the input fields before it is submitted to the server. It could save some time if those functions are short, simple and quick to compute.
In case you need a more complex validation checks which relay on Moodle's internal PHP libraries (or other/external PHP libraries) you better use the ''Server side'' validation checks. Where you can query the DB, write complex PHP validation functions and much much more, that are not available (easily) when using JavaScript on the client's side.

==setHelpButton==
{{Moodle 1.9}}

<pre>
$mform->setHelpButton('lessondefault', array('lessondefault', get_string('lessondefault', 'lesson'), 'lesson'));
</pre>
First param is an elementname and the second param is an array of params that are passed to helpbutton in weblib.php. Params are :

<pre>
* @param string $page The keyword that defines a help page
* @param string $title The title of links, rollover tips, alt tags etc
* 'Help with' (or the language equivalent) will be prefixed and '...' will be stripped.
* @param string $module Which module is the page defined in
* @param mixed $image Use a help image for the link? (true/false/"both")
* @param boolean $linktext If true, display the title next to the help icon.
* @param string $text If defined then this text is used in the page, and
* the $page variable is ignored.
* @param boolean $return If true then the output is returned as a string, if false it is printed to the current page.
* @param string $imagetext The full text for the helpbutton icon. If empty use default help.gif
</pre>
Make sure you don't set boolean $return to false.

You need to do use this method after addElement();

==addHelpButton==
{{Moodle 2.0}}

<pre>
$mform->addHelpButton('api_key_field', 'api_key', 'block_extsearch');
</pre>

In Moodle 2.0 the "setHelpButton" method has been deprecated in favor of the "addHelpButton" method, which has a simplified interface and uses $OUTPUT->help_icon() on the back end. The following parameters are expected:

* @param $elementname The name of the form element to add the help button for
* @param $identifier The identifier for the help string and its title (see below)
* @param $component The component name to look for the help string in

Unlike in Moodle 1.9, it is no longer necessary to put your help pages in separate HTML files. Instead, the function looks for two strings:

1. get_string($identifier, $component): The title of the help page
2. get_string("{$identifier}_help", $component): The content of the help page

So you will need to have '''$identifier''' and '''{$identifier}_help''' defined in order for the help button to be created properly. For example the multiple choice question editing form has a button for shuffling the answers.
<pre>
$mform->addHelpButton('shuffleanswers', 'shuffleanswers', 'qtype_multichoice');
</pre>
and so the language file includes the strings
<pre>
$string['shuffleanswers'] = 'Shuffle the choices?';
$string['shuffleanswers_help'] = 'If enabled,.....
</pre>
==setDefault==

<pre>
$mform->addElement('select', 'grade', get_string('gradeforsubmission', 'exercise'), $grades);
$mform->setHelpButton('grade', array('grade', get_string('gradeforsubmission', 'exercise'), 'exercise'));
$mform->setDefault('grade', 100);
</pre>

Set the default of the form value with setDefault($elementname, $value); where elementname is the elementname whose default you want to set and $value is the default to set. We set the defaults for the form in definition(). This default is what is used if no data is loaded into the form with set_data(); eg. on display of the form for an 'add' rather than 'update' function.

==disabledIf==

For any element or groups of element in a form you can conditionally disable the group or individual element depending on conditions.

You can use $mform->disabledIf($elementName, $dependentOn, $condition = 'notchecked', $value='1')

* elementname can be a group. If you specify a group all elements in the group will be disabled (if dependentOn is in elementname group that is ignored and not disabled). These are the element names you've used as the second argument in addElement or addGroup.
* dependentOn is the actual name of the element as it will appear in html. This can be different to the name used in addGroup particularly but also addElement where you're adding a complex element like a date_selector. Check the html of your page. You typically make the depedentOn a checkbox or select box.
* $condition will be 'notchecked', 'checked', 'noitemselected', 'eq' or, if it is anything else, we test for 'neq'.
** If $condition is 'eq' or 'neq' then we check the value of the dependentOn field and check for equality (==) or nonequality (!=) in js
** If $condition is 'checked' or 'notchecked' then we check to see if a checkbox is checked or not.
** If $condition is 'noitemselected' then we check to see whether nothing is selected in a dropdown list.

Examples:
// Disable my control unless a checkbox is checked.
$mform->disabledIf('mycontrol', 'somecheckbox');

// Disable my control if a checkbox '''is''' checked.
$mform->disabledIf('mycontrol', 'somecheckbox', 'checked');

// Disable my control unless a dropdown has value 42.
$mform->disabledIf('mycontrol', 'someselect', 'eq', 42);

The possible choices here are in the function lockoptionsall in lib/javascript-static.js.

==setType==

PARAM_* types are used to specify how a submitted variable should be cleaned. These should be used for get parameters such as id, course etc. which are used to load a page and also with setType(); method. Every form element should have a type specified except select, radio box and checkbox elements, these elements do a good job of cleaning themselves (only specified options are allowed as user input).

===Most Commonly Used PARAM_* Types===

These are the most commonly used PARAM_* types and their proper uses. More types can be seen in moodlelib.php starting around line 100.

* PARAM_CLEAN is deprecated and you should try to use a more specific type.
* PARAM_TEXT should be used for cleaning data that is expected to be plain text. It will strip all html tags. But will still let tags for multilang support through.
* PARAM_NOTAGS should be used for cleaning data that is expected to be plain text. It will strip *all* html type tags. It will still *not* let tags for multilang support through. This should be used for instance for email addresses where no multilang support is appropriate.
* PARAM_RAW means no cleaning whatsoever, it is used mostly for data from the html editor. Data from the editor is later cleaned before display using format_text() function. PARAM_RAW can also be used for data that is validated by some other way or printed by p() or s().
* PARAM_INT should be used for integers.
* PARAM_ACTION is an alias of PARAM_ALPHA and is used for hidden fields specifying form actions.

==References==

* [http://www.midnighthax.com/quickform.php PEAR HTML QuickForm Getting Started Guide] by Keith Edmunds of Midnighthax.com
* [http://pear.php.net/manual/en/package.html.html-quickform.php PEAR::HTML_QuickForm manual]

[[Category:Formslib]]

If you have problems creating php forms you may get them with form builder http://phpforms.net/tutorial/html-basics/form-builder.html

Data manipulation API

2011-09-06T06:52:09Z

Fpirsch: /* Getting a single record */

{{Moodle_2.0}}This page describes the functions available to access data in the Moodle database. You should '''exclusively''' use these functions in order to retrieve or modify database content because these functions provide a high level of abstraction and guarantee that your database manipulation will work against different RDBMSes.

Where possible, tricks and examples will be documented here in order to make developers' lives a bit easier. Of course, feel free to clarify, complete and add more information to this documentation. It will be welcome, absolutely!

== Main info ==

'''Important note:''' All the functions shown on this page are for use in '''Moodle 2.0 upwards''', where we changed the [[DB layer 2.0|DB layer]] to support some new features. If you need information for previous Moodle version, take a look to the [[DML functions - pre 2.0|DML functions - pre 2.0]] page. For a detailed reference of changes, see the [[DB layer 2.0 migration docs|migration docs]].

* All the function calls on this page are public methods of the $DB global object, so you'll need to "import" it within your functions (not needed in global scripts) with one simple:
<code php>global $DB;</code>
* The $DB global object is an instance of the moodle_database class, which is defined in [http://cvs.moodle.org/moodle/lib/dml/moodle_database.php?view=markup moodle_database.php]
* All the $table parameters in the functions are meant to be the table name ''without'' prefixes.
<code php>$user = $DB->get_record('user', array('id'=>'1');</code>
* When using the xxx_sql() functions, table names must be enclosed between curly braces.
<code php>$user = $DB->get_record_sql('SELECT * FROM {user} WHERE id = ?', array(1));</code>
* All the $conditions parameters in the functions are arrays of fieldname=>fieldvalue elements.
<code php>$user = $DB->get_record('user', array('firstname'=>'Martin', 'lastname'=>'Dougiamas'));</code>
* All the $params parameters in the functions are arrays of values used to fill placeholders in SQL statements. Both the question mark and named placeholders can be used. Note that named params '''must be unique''' even if the value passed is the same.
<code php>
/// Question mark placeholders:
$DB->get_record_sql('SELECT * FROM {user} WHERE firstname = ? AND lastname = ?',
array('Martin', 'Dougiamas'));

/// Named placeholders:
$DB->get_record_sql('SELECT * FROM {user} WHERE firstname = :firstname AND lastname = :lastname',
array('firstname'=>'Martin', 'lastname'=>'Dougiamas'));
</code>

== The functions ==

===Seeing how many records match a given criteria===
<code php>
o $DB->count_records($table, array $conditions=null)
/// Count the records in a table where all the given conditions met.
o $DB->count_records_select($table, $select, array $params=null, $countitem="COUNT('x')")
/// Count the records in a table which match a particular WHERE clause.
o $DB->count_records_sql($sql, array $params=null)
/// Get the result of a SQL SELECT COUNT(...) query.
</code>

===Seeing if one record exists===
<code php>
o $DB->record_exists($table, array $conditions=null)
/// Test whether a record exists in a table where all the given conditions met.
o $DB->record_exists_select($table, $select, array $params=null)
/// Test whether any records exists in a table which match a particular WHERE clause.
o $DB->record_exists_sql($sql, array $params=null)
/// Test whether a SQL SELECT statement returns any records.
</code>

===Getting a single record===

<code php>
o $DB->get_record($table, array $conditions, $fields='*', $strictness=IGNORE_MISSING)
/// Get a single database record as an object where all the given conditions met.
/// @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
/// IGNORE_MULTIPLE means return first, ignore multiple records found(not recommended);
/// MUST_EXIST means throw exception if no record or multiple records found
o $DB->get_record_select($table, $select, array $params=null, $fields='*', $strictness=IGNORE_MISSING)
/// Get a single database record as an object which match a particular WHERE clause.
o $DB->get_record_sql($sql, array $params=null, $strictness=IGNORE_MISSING)
/// Get a single database record as an object using a SQL statement.
</code>

===Getting an array of records===
Each of the following methods return an array of objects. The array is indexed by the first column of the fields returned by the query. Thus to assure consistent data, it appears to be best practice to ensure that your query include an "id column" as the first field. (When developing custom tables, be sure to make id your first column for this reason!)
<code php>
o $DB->get_records($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as an array of objects where all the given conditions met.
o $DB->get_records_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as an array of objects which match a particular WHERE clause.
o $DB->get_records_sql($sql, array $params=null, $limitfrom=0, $limitnum=0)
/// Get a number of records as an array of objects using a SQL statement.
o $DB->get_records_list($table, $field, array $values, $sort='', $fields='*', $limitfrom='', $limitnum='')
/// Get a number of records as an array of objects where one field match one list of values.
</code>

The following methods return data as key/value pairs in an associative array.
<code php>
o $DB->get_records_menu($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get the first two columns from a number of records as an associative array where all the given conditions met.
o $DB->get_records_select_menu($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get the first two columns from a number of records as an associative array which match a particular WHERE clause.
o $DB->get_records_sql_menu($sql, array $params=null, $limitfrom=0, $limitnum=0)
/// Get the first two columns from a number of records as an associative array using a SQL statement.
</code>
====Examples====
=====moodle_database::get_records()=====
Get a number of records as an array of objects where all the given conditions met.
<code php>
///Get all records where foo = bar
$result = $DB->get_records($table,array('foo'=>'bar'));

///Get all records where foo = bar and jon = doe
$result = $DB->get_records($table,array('foo' => 'bar AND' , 'jon' => 'doe'));

///Get all records where foo = bar, but only return the fields foo,bar,jon,doe
$result = $DB->get_records($table,array('foo'=>'bar'),null,'foo,bar,jon,doe');
///The previous example would cause data issues unless the 'foo' field happens to have unique values.
</code>

=====moodle_database::get_records_select()=====
Get a number of records as an array of objects which match a particular WHERE clause.
<code php>
///Get all records where jon = 'doe' and bob is not = 'tom'
///The 'select' parameter is (if not empty) is dropped directly into the WHERE clause without alteration.
$table = 'foo';
$select = 'jon = 'doe' AND bob != "tom" '; //is put into the where clause
$result = $DB->get_records_select($table,$select);
</code>

=====moodle_database::get_records_sql()=====
Get a number of records as an array of objects using a SQL statement. Defined as an abstract function in moodle_database, this method is implemented per database type.
<code php>
///Get all records from 'table' where foo = bar
$result = $DB->get_records('SELECT * FROM table WHERE foo = ?',array('bar');

///Get all records from 'table' where foo = 'bar' and bob = 'tom'
///This is somewhat similar to how Drupal makes its queries
$result = $DB->get_records('SELECT * FROM table WHERE foo = ? AND bob = ?', array( 'bar' , 'tom' );
</code>

=====moodle_database::get_records_list()=====
Get a number of records as an array of objects where one field match one list of values.
<code php>
///Get all records where the values('bar',1,'elephant','moodle') are found in the field 'foo'
$result = $DB->get_records($table, 'foo', array( 'bar', 1, 'elephant', 'moodle'));

///Get all records where the values('bar',1,'elephant','moodle') are found in the field 'foo'
///Only returning the fields 'id', 'test' and 'taco'
$result = $DB->get_records($table, 'foo', array( 'bar', 1, 'elephant', 'moodle')null, 'id,test,taco');
</code>

=====moodle_database::get_records_menu()=====
Get the first two columns from a number of records as an associative array where all the given conditions met.
You can choose the two fields or leave the parameter blank and the method will return the first two columns of the table.
Returns an associative array.
<code php>
///Get all records from table 'foo' where column 'foo' is equal to the value 'bar'
$table = 'foo'; ///name of table
$conditions = array('foo'=>'bar'); ///the name of the field (key) and the desired value

$result = $DB->get_records_menu($table,$conditions));

///Get all records from table 'foo' where column 'foo' is equal to the value 'bar'
///Returning the values from the columns 'id' and 'tacos'
$table = 'foo'; ///name of table
$conditions = array('foo'=>'bar'); ///the name of the field (key) and the desired value
$fields = 'id, tacos'; ///list of fields to return

$result = $DB->get_records_menu($table,$conditions));

</code>
The result of this last example will look something like:
<code php>
/// The value of the id field is 909 and the value of the 'tacos' column is 6
array(1) { [909]=6 }
</code>

=====moodle_database::get_records_select_menu()=====
Get the first two columns from a number of records as an associative array which match a particular WHERE clause.
<code php>
///Get all records where jon = 'doe' and bob is not = 'tom'
///The 'select' parameter is (if not empty) is dropped directly into the WHERE clause without alteration.
$table = 'foo';
$select = 'jon = "doe" AND bob != "tom" '; //is put into the where clause
$result = $DB->get_records_select_menu($table,$select);

$table = 'foo';
$select = 'jon = "doe" AND bob != "tom" '; //is put into the where clause
$fields = 'id, tacos';//return these fields
$result = $DB->get_records_select_menu($table,$select,null,$fields);
</code>

The result of this last example will look something like:
<code php>
/// The value of the id field is 909 and the value of the 'tacos' column is 6
array(1) { [909]=6 }
</code>

=====moodle_database::get_records_sql_menu()=====
Get the first two columns from a number of records as an associative array using a SQL statement.
<code php>
///Get all records from table foo where bar = 6
$sql = 'SELECT * FROM foo WHERE bar = ?';
$params = array(6);

$result = $DB->get_records_sql_menu($sql,$params);

///Get all records from table foo where bar = 6
$sql = 'SELECT id,tacos FROM foo WHERE bar = ?';
$params = array(6);

$result = $DB->get_records_sql_menu($sql,$params);

</code>

The result of this last example will look something like:
<code php>
/// The value of the id field is 909 and the value of the 'tacos' column is 6
array(1) { [909]=6 }
</code>

===Getting a particular field value from one record===
<code php>
o $DB->get_field($table, $return, array $conditions)
/// Get a single field value from a table record where all the given conditions met.
o $DB->get_field_select($table, $return, $select, array $params=null)
/// Get a single field value from a table record which match a particular WHERE clause.
o $DB->get_field_sql($sql, array $params=null)
/// Get a single field value (first field) using a SQL statement.
</code>

===Getting a particular field value from various records===

<code php>
o $DB->get_fieldset_select($table, $return, $select, array $params=null)
/// Selects records and return values of chosen field as an array which match a particular WHERE clause.
o $DB->get_fieldset_sql($sql, array $params=null)
/// Selects records and return values (first field) as an array using a SQL statement.
</code>

===Setting a particular field in the database===
<code php>
o $DB->set_field($table, $newfield, $newvalue, array $conditions=null)
/// Set a single field in every table record where all the given conditions met.
o $DB->set_field_select($table, $newfield, $newvalue, $select, array $params=null)
/// Set a single field in every table record which match a particular WHERE clause.
</code>

===Deleting Records===
<code php>
o $DB->delete_records($table, array $conditions=null)
/// Delete the records from a table where all the given conditions met.
o $DB->delete_records_select($table, $select, array $params=null)
/// Delete one or more records from a table which match a particular WHERE clause.
</code>

===Inserting Records===
The method to insert records is called aptly enough, insert_record(). The method accepts 4 parameters, but the fourth, "bulk", in most implementations is unused.
<code php>
o $DB->insert_record($table, $dataobject, $returnid=true, $bulk=false)
/// Insert a record into a table and return the "id" field if required.
</code>
====Example(s)====
<code php>
$record = new stdClass();
$record->name = 'overview';
$record->displayorder = '10000';
$DB->insert_record('quiz_report', $record, false);
</code>

<code php>
$record = new stdClass();
$record->name = 'overview';
$record->displayorder = '10000';
$lastinsertid = $DB->insert_record('quiz_report', $record);
</code>

===Updating Records===
<code php>
o $DB->update_record($table, $dataobject, $bulk=false)
/// Update a record in a table.
</code>

===Using Recordsets===

Where the number of records to be retrieved from DB is high, the '''get_records_xxx()''' functions above are far from optimal, because they load all the records in memory at the same time. Under those circumstances, it is highly recommended to use these '''get_recordset_xxx()''' functions instead, which use one nice mechanism to iterate over all the target records and save a lot of memory.

Only one thing is '''absolutely important''': Don't forget to close the recordsets after using them! (This will free up a lot of resources in the RDBMS).

Here is the general way to iterate over records using the '''get_recordset_xxx()''' functions:

<code php>
$rs = $DB->get_recordset(....) {
foreach ($rs as $record) {
// Do whatever you want with this record
}
$rs->close(); // Don't forget to close the recordset!
</code>

And this is the list of available functions (100% paired with the get_records_xxx() above):
<code php>
o $DB->get_recordset($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as a moodle_recordset where all the given conditions met.
o $DB->get_recordset_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as a moodle_recordset which match a particular WHERE clause.
o $DB->get_recordset_sql($sql, array $params=null, $limitfrom=0, $limitnum=0);
/// Get a number of records as a moodle_recordset using a SQL statement.

o $DB->get_recordset_list($table, $field='', $values='', $sort='', $fields='*', $limitfrom='', $limitnum='')
/// Get a number of records as a moodle_recordset where one field matches one list of values.
</code>

===Delegated transactions===

* Please note some databases do not support transactions (such as the MyISAM MySQL database engine), however all server administrators are strongly encouraged to migrate to databases that support transactions (such as the InnoDB MySQL database engine).
* Previous versions supported only one level of transaction. Since Moodle 2.0, the DML layer emulates delegated transactions that allow nesting of transactions.
* Transactions should not be used much in Moodle core; they are intended for various plugins such as web services, enrol and auth plugins.
* Some subsystems (such as messaging) do not support transactions because is it is not possible to rollback in external systems.

A transaction is started by:
<code php>
$transaction = $DB->start_delegated_transaction();
</code>

and finished by:
<code php>
$transaction->allow_commit();
</code>

Usually a transaction is rolled back when an exception is thrown. <code>$transaction->rollback($ex);</code> must be used very carefully because it might break compatibility with databases that do not support transactions. Transactions cannot be used as part of expected code flow; they can be used only as an emergency protection of data consistency.

See more details in [[DB layer 2.0 delegated transactions]] or MDL-20625.

====Example(s)====

<code php>
global $DB;
try {
$transaction = $DB->start_delegated_transaction();
// Insert a record
$DB->insert('foo', $object);
$DB->insert('bar', $otherobject);

// Assuming the both inserts work, we get to the following line.
$transaction->allow_commit();
} catch(Exception $e) {
$transaction->rollback($e);
}
</code>

===Helper Functions===

In order have real cross-db compatibility, there are some helper functions used to build SQL fragments based on the DB Moodle is running. Using them we'll avoid conditional queries here and there and have those "incompatibilities" fixed once and for ever.
<code php>
o $DB->sql_bitand($int1, $int2)
/// Returns the SQL text to be used in order to perform one bitwise AND
/// operation between 2 integers.
o $DB->sql_bitnot($int1)
/// Returns the SQL text to be used in order to perform one bitwise NOT
/// operation with 1 integer.
o $DB->sql_bitor($int1, $int2)
/// Returns the SQL text to be used in order to perform one bitwise OR
/// operation between 2 integers.
o $DB->sql_bitxor($int1, $int2)
/// Returns the SQL text to be used in order to perform one bitwise XOR
/// operation between 2 integers.

o $DB->sql_null_from_clause()
/// Returns the FROM clause required by some DBs in all SELECT statements.

o $DB->sql_ceil($fieldname)
/// Returns the correct CEIL expression applied to fieldname.
o $DB->sql_like($fieldname, $param, $casesensitive = true, $accentsensitive = true, $notlike = false, $escapechar = ' \\ ')
/// Returns the proper SQL to do LIKE.
o $DB->sql_length($fieldname)
/// Returns the SQL text to be used to calculate the length in characters of one expression.
o $DB->sql_modulo($int1, $int2)
/// Returns the SQL text to be used in order to calculate module - remainder after division
o $DB->sql_position($needle, $haystack)
/// Returns the SQL for returning searching one string for the location of another.
/// Note: If using placeholders BOTH in $needle and $haystack, they MUST be named placeholders.
o $DB->sql_substr($expr, $start, $length=false)
/// Returns the proper substr() SQL text used to extract substrings from DB.
/// Note: This fuction has changed in Moodle 2.0 and now at least 2 params are mandatory.
/// Note: Now it returns the whole SQL text to be used instead of only the function name.

o $DB->sql_cast_char2int($fieldname, $text=false)
/// Returns the SQL to be used in order to CAST one CHAR column to INTEGER.
o $DB->sql_cast_char2real($fieldname, $text=false)
/// Returns the SQL to be used in order to CAST one CHAR column to REAL number.

o $DB->sql_compare_text($fieldname, $numchars=32)
/// Returns the SQL text to be used to compare one TEXT (clob) column.
/// with one VARCHAR column.
o $DB->sql_order_by_text($fieldname, $numchars=32)
/// Returns the SQL text to be used to order by one TEXT (clob) column.

o $DB->sql_concat()
/// Returns the proper SQL to do CONCAT between the elements passed.
o $DB->sql_concat_join($separator="' '", $elements=array())
/// Returns the proper SQL to do CONCAT between the elements passed using one separator.
o $DB->sql_fullname($first='firstname', $last='lastname')
/// Returns the proper SQL to concatenate $firstname and $lastname.

o $DB->sql_isempty($tablename, $fieldname, $nullablefield, $textfield)
/// Returns the proper SQL to know if one field is empty.
o $DB->sql_isnotempty($tablename, $fieldname, $nullablefield, $textfield)
/// Returns the proper SQL to know if one field is not empty.
o $DB->sql_empty()
/// Returns the empty string char used by every supported DB.
</code>

==See also==

* [[DML exceptions|DML exceptions]]: New DML code is throwing exceptions instead of returning false if anything goes wrong
* [[DML drivers|DML drivers]]: Database drivers for new DML layer
* [[DML functions - pre 2.0|DML functions - pre 2.0]]: '''(deprecated!)''' For information valid before Moodle 2.0.
* [[DDL functions|DDL functions]]: Where all the functions used to handle DB objects ([[wikipedia:Data_Definition_Language|DDL]]) are defined.
* [[DB layer 2.0 examples|DB layer 2.0 examples]]: To see some code examples using various DML functions.
* [[DB layer 2.0 migration docs|DB layer 2.0 migration docs]]: Information about how to modify your code to work with the new Moodle 2.0 DB layer.
* [[DTL functions|DTL functions]]: Exporting, importing and moving of data stored in SQL databases

[[Category:DB]]
[[Category:XMLDB]]

Data manipulation API

2011-09-06T06:38:39Z

Fpirsch: /* Main info */

{{Moodle_2.0}}This page describes the functions available to access data in the Moodle database. You should '''exclusively''' use these functions in order to retrieve or modify database content because these functions provide a high level of abstraction and guarantee that your database manipulation will work against different RDBMSes.

Where possible, tricks and examples will be documented here in order to make developers' lives a bit easier. Of course, feel free to clarify, complete and add more information to this documentation. It will be welcome, absolutely!

== Main info ==

'''Important note:''' All the functions shown on this page are for use in '''Moodle 2.0 upwards''', where we changed the [[DB layer 2.0|DB layer]] to support some new features. If you need information for previous Moodle version, take a look to the [[DML functions - pre 2.0|DML functions - pre 2.0]] page. For a detailed reference of changes, see the [[DB layer 2.0 migration docs|migration docs]].

* All the function calls on this page are public methods of the $DB global object, so you'll need to "import" it within your functions (not needed in global scripts) with one simple:
<code php>global $DB;</code>
* The $DB global object is an instance of the moodle_database class, which is defined in [http://cvs.moodle.org/moodle/lib/dml/moodle_database.php?view=markup moodle_database.php]
* All the $table parameters in the functions are meant to be the table name ''without'' prefixes.
<code php>$user = $DB->get_record('user', array('id'=>'1');</code>
* When using the xxx_sql() functions, table names must be enclosed between curly braces.
<code php>$user = $DB->get_record_sql('SELECT * FROM {user} WHERE id = ?', array(1));</code>
* All the $conditions parameters in the functions are arrays of fieldname=>fieldvalue elements.
<code php>$user = $DB->get_record('user', array('firstname'=>'Martin', 'lastname'=>'Dougiamas'));</code>
* All the $params parameters in the functions are arrays of values used to fill placeholders in SQL statements. Both the question mark and named placeholders can be used. Note that named params '''must be unique''' even if the value passed is the same.
<code php>
/// Question mark placeholders:
$DB->get_record_sql('SELECT * FROM {user} WHERE firstname = ? AND lastname = ?',
array('Martin', 'Dougiamas'));

/// Named placeholders:
$DB->get_record_sql('SELECT * FROM {user} WHERE firstname = :firstname AND lastname = :lastname',
array('firstname'=>'Martin', 'lastname'=>'Dougiamas'));
</code>

== The functions ==

===Seeing how many records match a given criteria===
<code php>
o $DB->count_records($table, array $conditions=null)
/// Count the records in a table where all the given conditions met.
o $DB->count_records_select($table, $select, array $params=null, $countitem="COUNT('x')")
/// Count the records in a table which match a particular WHERE clause.
o $DB->count_records_sql($sql, array $params=null)
/// Get the result of a SQL SELECT COUNT(...) query.
</code>

===Seeing if one record exists===
<code php>
o $DB->record_exists($table, array $conditions=null)
/// Test whether a record exists in a table where all the given conditions met.
o $DB->record_exists_select($table, $select, array $params=null)
/// Test whether any records exists in a table which match a particular WHERE clause.
o $DB->record_exists_sql($sql, array $params=null)
/// Test whether a SQL SELECT statement returns any records.
</code>

===Getting a single record===

<code php>
o $DB->get_record($table, array $conditions, $fields='*', $ignoremultiple=false)
/// Get a single database record as an object where all the given conditions met.
o $DB->get_record_select($table, $select, array $params=null, $fields='*', $ignoremultiple=false)
/// Get a single database record as an object which match a particular WHERE clause.
o $DB->get_record_sql($sql, array $params=null)
/// Get a single database record as an object using a SQL statement.
</code>

===Getting an array of records===
Each of the following methods return an array of objects. The array is indexed by the first column of the fields returned by the query. Thus to assure consistent data, it appears to be best practice to ensure that your query include an "id column" as the first field. (When developing custom tables, be sure to make id your first column for this reason!)
<code php>
o $DB->get_records($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as an array of objects where all the given conditions met.
o $DB->get_records_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as an array of objects which match a particular WHERE clause.
o $DB->get_records_sql($sql, array $params=null, $limitfrom=0, $limitnum=0)
/// Get a number of records as an array of objects using a SQL statement.
o $DB->get_records_list($table, $field, array $values, $sort='', $fields='*', $limitfrom='', $limitnum='')
/// Get a number of records as an array of objects where one field match one list of values.
</code>

The following methods return data as key/value pairs in an associative array.
<code php>
o $DB->get_records_menu($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get the first two columns from a number of records as an associative array where all the given conditions met.
o $DB->get_records_select_menu($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get the first two columns from a number of records as an associative array which match a particular WHERE clause.
o $DB->get_records_sql_menu($sql, array $params=null, $limitfrom=0, $limitnum=0)
/// Get the first two columns from a number of records as an associative array using a SQL statement.
</code>
====Examples====
=====moodle_database::get_records()=====
Get a number of records as an array of objects where all the given conditions met.
<code php>
///Get all records where foo = bar
$result = $DB->get_records($table,array('foo'=>'bar'));

///Get all records where foo = bar and jon = doe
$result = $DB->get_records($table,array('foo' => 'bar AND' , 'jon' => 'doe'));

///Get all records where foo = bar, but only return the fields foo,bar,jon,doe
$result = $DB->get_records($table,array('foo'=>'bar'),null,'foo,bar,jon,doe');
///The previous example would cause data issues unless the 'foo' field happens to have unique values.
</code>

=====moodle_database::get_records_select()=====
Get a number of records as an array of objects which match a particular WHERE clause.
<code php>
///Get all records where jon = 'doe' and bob is not = 'tom'
///The 'select' parameter is (if not empty) is dropped directly into the WHERE clause without alteration.
$table = 'foo';
$select = 'jon = 'doe' AND bob != "tom" '; //is put into the where clause
$result = $DB->get_records_select($table,$select);
</code>

=====moodle_database::get_records_sql()=====
Get a number of records as an array of objects using a SQL statement. Defined as an abstract function in moodle_database, this method is implemented per database type.
<code php>
///Get all records from 'table' where foo = bar
$result = $DB->get_records('SELECT * FROM table WHERE foo = ?',array('bar');

///Get all records from 'table' where foo = 'bar' and bob = 'tom'
///This is somewhat similar to how Drupal makes its queries
$result = $DB->get_records('SELECT * FROM table WHERE foo = ? AND bob = ?', array( 'bar' , 'tom' );
</code>

=====moodle_database::get_records_list()=====
Get a number of records as an array of objects where one field match one list of values.
<code php>
///Get all records where the values('bar',1,'elephant','moodle') are found in the field 'foo'
$result = $DB->get_records($table, 'foo', array( 'bar', 1, 'elephant', 'moodle'));

///Get all records where the values('bar',1,'elephant','moodle') are found in the field 'foo'
///Only returning the fields 'id', 'test' and 'taco'
$result = $DB->get_records($table, 'foo', array( 'bar', 1, 'elephant', 'moodle')null, 'id,test,taco');
</code>

=====moodle_database::get_records_menu()=====
Get the first two columns from a number of records as an associative array where all the given conditions met.
You can choose the two fields or leave the parameter blank and the method will return the first two columns of the table.
Returns an associative array.
<code php>
///Get all records from table 'foo' where column 'foo' is equal to the value 'bar'
$table = 'foo'; ///name of table
$conditions = array('foo'=>'bar'); ///the name of the field (key) and the desired value

$result = $DB->get_records_menu($table,$conditions));

///Get all records from table 'foo' where column 'foo' is equal to the value 'bar'
///Returning the values from the columns 'id' and 'tacos'
$table = 'foo'; ///name of table
$conditions = array('foo'=>'bar'); ///the name of the field (key) and the desired value
$fields = 'id, tacos'; ///list of fields to return

$result = $DB->get_records_menu($table,$conditions));

</code>
The result of this last example will look something like:
<code php>
/// The value of the id field is 909 and the value of the 'tacos' column is 6
array(1) { [909]=6 }
</code>

=====moodle_database::get_records_select_menu()=====
Get the first two columns from a number of records as an associative array which match a particular WHERE clause.
<code php>
///Get all records where jon = 'doe' and bob is not = 'tom'
///The 'select' parameter is (if not empty) is dropped directly into the WHERE clause without alteration.
$table = 'foo';
$select = 'jon = "doe" AND bob != "tom" '; //is put into the where clause
$result = $DB->get_records_select_menu($table,$select);

$table = 'foo';
$select = 'jon = "doe" AND bob != "tom" '; //is put into the where clause
$fields = 'id, tacos';//return these fields
$result = $DB->get_records_select_menu($table,$select,null,$fields);
</code>

The result of this last example will look something like:
<code php>
/// The value of the id field is 909 and the value of the 'tacos' column is 6
array(1) { [909]=6 }
</code>

=====moodle_database::get_records_sql_menu()=====
Get the first two columns from a number of records as an associative array using a SQL statement.
<code php>
///Get all records from table foo where bar = 6
$sql = 'SELECT * FROM foo WHERE bar = ?';
$params = array(6);

$result = $DB->get_records_sql_menu($sql,$params);

///Get all records from table foo where bar = 6
$sql = 'SELECT id,tacos FROM foo WHERE bar = ?';
$params = array(6);

$result = $DB->get_records_sql_menu($sql,$params);

</code>

The result of this last example will look something like:
<code php>
/// The value of the id field is 909 and the value of the 'tacos' column is 6
array(1) { [909]=6 }
</code>

===Getting a particular field value from one record===
<code php>
o $DB->get_field($table, $return, array $conditions)
/// Get a single field value from a table record where all the given conditions met.
o $DB->get_field_select($table, $return, $select, array $params=null)
/// Get a single field value from a table record which match a particular WHERE clause.
o $DB->get_field_sql($sql, array $params=null)
/// Get a single field value (first field) using a SQL statement.
</code>

===Getting a particular field value from various records===

<code php>
o $DB->get_fieldset_select($table, $return, $select, array $params=null)
/// Selects records and return values of chosen field as an array which match a particular WHERE clause.
o $DB->get_fieldset_sql($sql, array $params=null)
/// Selects records and return values (first field) as an array using a SQL statement.
</code>

===Setting a particular field in the database===
<code php>
o $DB->set_field($table, $newfield, $newvalue, array $conditions=null)
/// Set a single field in every table record where all the given conditions met.
o $DB->set_field_select($table, $newfield, $newvalue, $select, array $params=null)
/// Set a single field in every table record which match a particular WHERE clause.
</code>

===Deleting Records===
<code php>
o $DB->delete_records($table, array $conditions=null)
/// Delete the records from a table where all the given conditions met.
o $DB->delete_records_select($table, $select, array $params=null)
/// Delete one or more records from a table which match a particular WHERE clause.
</code>

===Inserting Records===
The method to insert records is called aptly enough, insert_record(). The method accepts 4 parameters, but the fourth, "bulk", in most implementations is unused.
<code php>
o $DB->insert_record($table, $dataobject, $returnid=true, $bulk=false)
/// Insert a record into a table and return the "id" field if required.
</code>
====Example(s)====
<code php>
$record = new stdClass();
$record->name = 'overview';
$record->displayorder = '10000';
$DB->insert_record('quiz_report', $record, false);
</code>

<code php>
$record = new stdClass();
$record->name = 'overview';
$record->displayorder = '10000';
$lastinsertid = $DB->insert_record('quiz_report', $record);
</code>

===Updating Records===
<code php>
o $DB->update_record($table, $dataobject, $bulk=false)
/// Update a record in a table.
</code>

===Using Recordsets===

Where the number of records to be retrieved from DB is high, the '''get_records_xxx()''' functions above are far from optimal, because they load all the records in memory at the same time. Under those circumstances, it is highly recommended to use these '''get_recordset_xxx()''' functions instead, which use one nice mechanism to iterate over all the target records and save a lot of memory.

Only one thing is '''absolutely important''': Don't forget to close the recordsets after using them! (This will free up a lot of resources in the RDBMS).

Here is the general way to iterate over records using the '''get_recordset_xxx()''' functions:

<code php>
$rs = $DB->get_recordset(....) {
foreach ($rs as $record) {
// Do whatever you want with this record
}
$rs->close(); // Don't forget to close the recordset!
</code>

And this is the list of available functions (100% paired with the get_records_xxx() above):
<code php>
o $DB->get_recordset($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as a moodle_recordset where all the given conditions met.
o $DB->get_recordset_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)
/// Get a number of records as a moodle_recordset which match a particular WHERE clause.
o $DB->get_recordset_sql($sql, array $params=null, $limitfrom=0, $limitnum=0);
/// Get a number of records as a moodle_recordset using a SQL statement.

o $DB->get_recordset_list($table, $field='', $values='', $sort='', $fields='*', $limitfrom='', $limitnum='')
/// Get a number of records as a moodle_recordset where one field matches one list of values.
</code>

===Delegated transactions===

* Please note some databases do not support transactions (such as the MyISAM MySQL database engine), however all server administrators are strongly encouraged to migrate to databases that support transactions (such as the InnoDB MySQL database engine).
* Previous versions supported only one level of transaction. Since Moodle 2.0, the DML layer emulates delegated transactions that allow nesting of transactions.
* Transactions should not be used much in Moodle core; they are intended for various plugins such as web services, enrol and auth plugins.
* Some subsystems (such as messaging) do not support transactions because is it is not possible to rollback in external systems.

A transaction is started by:
<code php>
$transaction = $DB->start_delegated_transaction();
</code>

and finished by:
<code php>
$transaction->allow_commit();
</code>

Usually a transaction is rolled back when an exception is thrown. <code>$transaction->rollback($ex);</code> must be used very carefully because it might break compatibility with databases that do not support transactions. Transactions cannot be used as part of expected code flow; they can be used only as an emergency protection of data consistency.

See more details in [[DB layer 2.0 delegated transactions]] or MDL-20625.

====Example(s)====

<code php>
global $DB;
try {
$transaction = $DB->start_delegated_transaction();
// Insert a record
$DB->insert('foo', $object);
$DB->insert('bar', $otherobject);

// Assuming the both inserts work, we get to the following line.
$transaction->allow_commit();
} catch(Exception $e) {
$transaction->rollback($e);
}
</code>

===Helper Functions===

In order have real cross-db compatibility, there are some helper functions used to build SQL fragments based on the DB Moodle is running. Using them we'll avoid conditional queries here and there and have those "incompatibilities" fixed once and for ever.
<code php>
o $DB->sql_bitand($int1, $int2)
/// Returns the SQL text to be used in order to perform one bitwise AND
/// operation between 2 integers.
o $DB->sql_bitnot($int1)
/// Returns the SQL text to be used in order to perform one bitwise NOT
/// operation with 1 integer.
o $DB->sql_bitor($int1, $int2)
/// Returns the SQL text to be used in order to perform one bitwise OR
/// operation between 2 integers.
o $DB->sql_bitxor($int1, $int2)
/// Returns the SQL text to be used in order to perform one bitwise XOR
/// operation between 2 integers.

o $DB->sql_null_from_clause()
/// Returns the FROM clause required by some DBs in all SELECT statements.

o $DB->sql_ceil($fieldname)
/// Returns the correct CEIL expression applied to fieldname.
o $DB->sql_like($fieldname, $param, $casesensitive = true, $accentsensitive = true, $notlike = false, $escapechar = ' \\ ')
/// Returns the proper SQL to do LIKE.
o $DB->sql_length($fieldname)
/// Returns the SQL text to be used to calculate the length in characters of one expression.
o $DB->sql_modulo($int1, $int2)
/// Returns the SQL text to be used in order to calculate module - remainder after division
o $DB->sql_position($needle, $haystack)
/// Returns the SQL for returning searching one string for the location of another.
/// Note: If using placeholders BOTH in $needle and $haystack, they MUST be named placeholders.
o $DB->sql_substr($expr, $start, $length=false)
/// Returns the proper substr() SQL text used to extract substrings from DB.
/// Note: This fuction has changed in Moodle 2.0 and now at least 2 params are mandatory.
/// Note: Now it returns the whole SQL text to be used instead of only the function name.

o $DB->sql_cast_char2int($fieldname, $text=false)
/// Returns the SQL to be used in order to CAST one CHAR column to INTEGER.
o $DB->sql_cast_char2real($fieldname, $text=false)
/// Returns the SQL to be used in order to CAST one CHAR column to REAL number.

o $DB->sql_compare_text($fieldname, $numchars=32)
/// Returns the SQL text to be used to compare one TEXT (clob) column.
/// with one VARCHAR column.
o $DB->sql_order_by_text($fieldname, $numchars=32)
/// Returns the SQL text to be used to order by one TEXT (clob) column.

o $DB->sql_concat()
/// Returns the proper SQL to do CONCAT between the elements passed.
o $DB->sql_concat_join($separator="' '", $elements=array())
/// Returns the proper SQL to do CONCAT between the elements passed using one separator.
o $DB->sql_fullname($first='firstname', $last='lastname')
/// Returns the proper SQL to concatenate $firstname and $lastname.

o $DB->sql_isempty($tablename, $fieldname, $nullablefield, $textfield)
/// Returns the proper SQL to know if one field is empty.
o $DB->sql_isnotempty($tablename, $fieldname, $nullablefield, $textfield)
/// Returns the proper SQL to know if one field is not empty.
o $DB->sql_empty()
/// Returns the empty string char used by every supported DB.
</code>

==See also==

* [[DML exceptions|DML exceptions]]: New DML code is throwing exceptions instead of returning false if anything goes wrong
* [[DML drivers|DML drivers]]: Database drivers for new DML layer
* [[DML functions - pre 2.0|DML functions - pre 2.0]]: '''(deprecated!)''' For information valid before Moodle 2.0.
* [[DDL functions|DDL functions]]: Where all the functions used to handle DB objects ([[wikipedia:Data_Definition_Language|DDL]]) are defined.
* [[DB layer 2.0 examples|DB layer 2.0 examples]]: To see some code examples using various DML functions.
* [[DB layer 2.0 migration docs|DB layer 2.0 migration docs]]: Information about how to modify your code to work with the new Moodle 2.0 DB layer.
* [[DTL functions|DTL functions]]: Exporting, importing and moving of data stored in SQL databases

[[Category:DB]]
[[Category:XMLDB]]