Difference between revisions of "External database enrolment"
Note: You are currently viewing documentation for Moodle 2.3. Up-to-date documentation for the latest stable version is available here: External database enrolment.
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[[fr:Base de données externe]]
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[[de:Einschreibung über externe Datenbank]]
[[de:Einschreibung über externe Datenbank]]
Revision as of 15:26, 19 April 2012
Location: External database edit settings link in Settings > Site administration > Plugins > Enrolments > Manage enrol plugins
You may use a external database (of nearly any kind) to control your enrolments. It is assumed your external database contains a field containing a course ID, a field containing a user ID, and optionally a field containing a role. These are compared against fields that you choose in the local course, user tables, and role tables.
The following are the supported data sources, but note that you will need to have to compiled PHP with the appropriate options or through ODBC.
Enrolment & Unenrolment
External database enrolment happens at the moment when a user logs into Moodle. The plugin will attempt to automatically enrol the student in all their courses according to the data in the external database and, optionally, create empty courses where they do not already exist. To check if it is working, you can log in as a student and then check that their list of courses is as you would expect.
The process also unenrols users from courses if they are no longer in the database. User records are marked according to their original enrolment method. Therefore the external database plugin can only unenrol users who were enroled by the plugin in the first place.
Courses that are set to "Course is not available to students" can be ignored for enrolment purposes by setting the "enrol_db_ignorehiddencourse" to yes.
Enrolment & Roles
The "enrol_db_defaultcourseroleid" setting in the plugin settings page specifies the role that the user will take when they are added to the course. The default setting will set them to the course default setting (initially "student"). However, you can specify a field in the external table (specified in the "enrol_db_remoterolefield" setting) that contains the short name for the user's role. This could, for example, be used to enrol both students and teachers into courses using a suitably configured database.
Optionally courses that do not exist in the Moodle site can be created. Switch the "enrol_db_autocreate" option to "yes" in the plugin settings. You can additionally specify the Category into which the new course will be placed and may also specify a "template" course from which the new course will be copied.
A script is provided that can synchronize all your user enrollments at once - both adding and removing user enrolments (and creating courses if specified). The script is called enrol_database_sync.php and is found in the enrol/database folder.
This script is meant to be called from a system cronjob to sync moodle enrolments with enrolments in the external database. You need to make sure all the users present in the external enrolments are already created in moodle. If you are using external authentication plugins (db, ldap, etc.) you can use the scripts provided by those plugins to synchronize your users before running this script.
Example cron entry for Moodle 2.0
# 5 minutes past 4am 5 4 * * * /usr/bin/php -c /path/to/php.ini /path/to/moodle/enrol/database/cli/sync.php
- If you have a large number of enrolments, you may want to raise the memory limits by passing -d memory_limit=256M
- For debugging & better logging, you are encouraged to use in the command line: -d log_errors=1 -d error_reporting=E_ALL -d display_errors=0 -d html_errors=0
- This only works for users that already exist in your Moodle site (see comment above)
Setting It Up (How to)
You will need to perform (as a minimum) the following steps to enable external database enrolment - only a single table is required in the database which contains a record for every user/course combination. If the table is large it is a good idea to make sure appropriate indexes have been created:
- Use an existing database or create a new one. Use an existing or create a new table with the following minimum fields:
- course identifier (to match unique course identifier in Moodle)
- user identifier (to match unique user identifier in Moodle)
- (optional) role identifier (to match unique role identifier in Moodle)
- Populate the database table. Each user/course combination to have a record in the table
- In Moodle, go to Site Administration => Courses => Enrolments, find External Database in the list and click Settings
- In the top panel, select the database type (make sure you have the necessary configuration in PHP for that type) and then supply the information to connect to the database.
- The middle panel creates the mapping between Moodle and the external database. The first three settings are for the local (Moodle) field names and the last three for the remote (external database) settings. They are in the same order.
- enrol_localcoursefield / enrol_remotecoursefield - in Moodle the name of the field in the course settings the uniquely identifies the course (e.g., idnumber). In the external database the name of the matching field.
- enrol_localuserfield / enrol_remoteuserfield - in Moodle the name of the field in the user profile that uniquely identified the user (e.g., idnumber). In the external database the name of the matching field.
- enrol_db_localrolefield / enrol_db_remoterolefield - (optional) in Moodle the name of the field in the role edit page the uniquely identifies the role (e.g., shortname). In the external database the name of the matching field.
- The Roles panel specifies the role that the user will get in the course if their role is not specified in the external database.
- The final panel enables auto creation of courses.
- Save changes, and then tick the box to enable external database enrolment.
The course enrolment drop down menu only lists interactive enrolment plugins. External database enrolment is not such a plugin, so it doesn't appear in the list. Similarly, the "Course Enrollable" setting (in the Course Settings) page also only applies to interactive enrolment plugins and has no effect on external database enrollment.
As of this writing, the only interactive enrolment plugins are manual (also know as internal), paypal and authorize.net.
Field Mapping Example:
Choose your fields from the Moodle database:
- enrol_localcoursefield: A course identifier from mdl_course, e.g. "idnumber"
- enrol_localuserfield: A user identifier from mdl_user, e.g. "idnumber"
- enrol_localrolefield: (optional) A role identifier from mdl_role, e.g. "shortname"
Create a view in your external database which matches the chosen field values from Moodle:
- enrol_remotecoursefield: A matching course identifier from your external database table, e.g. "course_number"
- enrol_remoteuserfield: A matching user identifier from your external database table, e.g. "userid"
- enrol_remoterolefield: (optional) A matching role identifier from your external database table, e.g. "role_name"
- It almost goes without saying that the integrity of the external database is important. If data is missing from the database then there is a potential for users being unenrolled from some or all of their courses. The unenrollment process will remove them from any group assignments and also poll each module type to give the module the option of removing that user's data if appropriate (for example, however, forum posts are never deleted). It is therefore prudent that you take the utmost care to ensure that the data in the external bass is correct at all times.
- Minor Security Issue Consider that if the ID field you use to identify your students is editable by the students (in their profile), then there is a potential for them changing this to the id of another valid student and gaining access to resources that they should not. However, they will still appear as themselves, they cannot impersonate the other user or otherwise gain access to their resources.
Errors and Diagnostics
The plugin produces a number of diagnostic messages and/or errors which are recorded to the PHP error log (as defined in the php.ini file). In addition messages about courses that are in the database for the user but that do not exist in the Moodle site will only be produced if debugging is set to ALL or DEVELOPER.
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- Example Setup  Example Database Enrollment Setup