Development:Question import/export formats

Importing or exporting questions

Template:Questiontype developer docs Questions coming from other Moodle courses or from other e-learning systems (i.e. Blackboard, Webct etc.) can be imported in Moodle. Similarlay Moodle offers a process to export questions to other systems in different format ( XML, QTI etc.). The import and export code is mostly written in format.php files located in a directory specific to the type of format files from which the import or export is done.

• examples:
  • question/format/aiken/format.php
  • question/format/blackboard/format.php
  • question/format/qti2/format.php
  • question/format/xml/format.php

there is a default class qformat_default defined in question/format.php and the process is controlled by

• question/import.php
• question/export.php

The simplest and most comprehensive import/export type is probably the Moodle XML format. It is worth studying this file (question/format/xml/format.php) along with the parent class (question/format.php) to get an understanding of what is going on. Some other custom formats circumvent the normal rules and structure and should be studied with caution.

Some things to note:

• Study the question/format.php file to establish which methods must be overridden.
• Each format.php file can support import, export or both indicated by the provide_import() and provide_export() methods
• Do not read or write directly to the database, this is handled for you by the parent class
• when importing, question objects need to be in a format suitable for use by the questiontype->save_options() method (see question/type/questiontype.php class). The easiest way to get this information is to do a print_r($question); at the start of the save_options() method for the appropriate question type when a question is saved. The imported object must be the same format.
• when importing, obtain 'empty' question objects from the defaultquestion() method, which sets all required properties to their default values.
• for exporting the $question object is supplied to the format class. Again, print_r($question) can be used to learn the format.

The format.php code flow for import

When importing questions

• the import.php selects the file and import format
  • pass the control to format.php and format/$format/format.php

$format being the selected file format ( Blackboard, XML etc.)

       require("format.php");  // Parent class
       require("format/$format/format.php");
       $classname = "qformat_$format";
       $qformat = new $classname();
       if (! $qformat->importpreprocess($category,$course)) {  // Do anything before that we need to
           error( $txt->importerror ,
                     "$CFG->wwwroot/question/import.php?courseid={$course->id}&category=$category->id");
       }
       if (! $qformat->importprocess($importfile, $params->matchgrades) ) {  // Process the uploaded file
           error( $txt->importerror ,
                 "$CFG->wwwroot/question/import.php?courseid={$course->id}&category=$category->id");
       }
       if (! $qformat->importpostprocess()) {                  // In case anything needs to be done after

• format.php call format/$format/format.php (i.e. the the specific format.php)

to read the imput file and return the questions (if any) that are in the imported files

        if (! $questions = $this->readquestions($lines)) {   // Extract all the questions
           notify( get_string('noquestionsinfile','quiz') );
           return false;
       }
       notify( get_string('importingquestions','quiz',count($questions)) );

• get list of valid answer grades

        $grades = get_grade_options();
       $gradeoptionsfull = $grades->gradeoptionsfull;

• Process some data and store each question

• check for answer grades validity (must match fixed list of grades)
• store question general parameters DIRECTLY in the dadabase

           $question->category = $this->category->id;
           $question->stamp = make_unique_id_code();  // Set the unique code (not to be changed)
           if (!$question->id = insert_record("question", $question)) {
               error( get_string('cannotinsert','quiz') );
           }
           $this->questionids[] = $question->id;

• save the options using the qtype->save_question_options() function

$QTYPES being the different questiontypes (shortanwer,truefalse etc.)

           global $QTYPES;
           $result = $QTYPES[$question->qtype]
                   ->save_question_options($question);

• diplay errors or notices

           if (!empty($result->error)) {
               notify($result->error);
               return false;
           }
           if (!empty($result->notice)) {
               notify($result->notice);
               return true;
           }

• if noerrors and no notices

Give the question a unique version stamp determined by question_hash()

           set_field('question', 'version', question_hash($question), 'id', $question->id);

Process the next question until the last question in the file

Return to the question or quiz editing.

See also

Lesson question types - both Lesson and Quiz can import the basic Moodle question types.