Groups API

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Groups in Moodle are collections of users within a course. They may be defined by the teacher in the course settings, or created automatically during a bulk user upload (eg from a text file). Groups can optionally be grouped together into named Groupings.

In the course settings, a teacher can choose whether a course uses groups or not, and whether those groups are separate (users can only see users in their own group) or visible (can see other groups just like teachers). This setting can be forced on all activities in the course, or not, allowing a lot of flexibility. The course-level groups mode also affects what is visible in course-wide reporting like the gradebook.

Additionally, activities can optionally be made visible to only one grouping at a time. In this case only the members of the groups in that grouping will be able to see that activity. If the user is in multiple groups then they have the ability to change their "current group" - this is a sticky enviroment variable that persists for the whole session. There is an experimental feature to restrict access to an activity only to those who are members of a group (in the applicable grouping).

There is a capability 'Access all groups' that lets some users (Typically teachers and admins) access the information about all groups, without being a member of them.

Most of these settings are handled by the core groups code and core groups API. If the activity module wants to implement group support, it need only use the Groups API to:

  • Find out the current settings for this instance of the activity
  • Show group controls (eg group selection menus) when appropriate
  • Explore memberships and structures of groups
  • Modify it's own interface to hide/show data accordingly

Note that this is mostly only useful to activity modules, and perhaps some blocks.

Group modes

There are three different group modes, these modes allow for restrictions to be put in place for access and visibility.

  • No groups - The course or activity has no groups.
  • Separate groups - Teachers and students can normally only see information relevant to that group.
  • Visible groups - Teachers and students are separated into groups but can still see all information.

This is explained in more detail on the Groups access control page.

File locations

The Groups API is all in lib/grouplib.php and is automatically included for you during the page setup.


  • get group information
    • groups_group_exists($groupid)
    • groups_get_group_name($groupid)
    • groups_get_group_by_name($courseid, $name)
    • groups_get_group_by_idnumber($courseid, $idnumber)
    • groups_get_group($groupid, $fields='*', $strictness=IGNORE_MISSING)
    • groups_get_all_groups($courseid, $userid=0, $groupingid=0, $fields='g.*')
    • groups_get_user_groups($courseid, $userid=0)
  • get grouping information
    • groups_get_grouping_name($groupingid)
    • groups_get_grouping_by_name($courseid, $name)
    • groups_get_grouping($groupingid, $fields='*', $strictness=IGNORE_MISSING)
    • groups_get_all_groupings($courseid)
  • print group information
    • groups_print_course_menu($course, $urlroot, $return=false)
    • groups_print_activity_menu($cm, $urlroot, $return=false, $hideallparticipants=false)
  • group membership
    • groups_is_member($groupid, $userid=null)
    • groups_has_membership($cm, $userid=null)
    • groups_get_members($groupid, $fields='u.*', $sort='lastname ASC')
    • groups_get_grouping_members($groupingid, $fields='u.*', $sort='lastname ASC')
  • course
    • groups_get_course_groupmode($course)
    • groups_get_course_group($course, $update=false, $allowedgroups=null)
    • groups_course_module_visible($cm, $userid=null)
  • activity
    • groups_get_activity_groupmode($cm, $course=null)
    • groups_get_activity_group($cm, $update=false, $allowedgroups=null)
    • groups_get_activity_allowed_groups($cm,$userid=0)


How to find and use the "current" group

This is using an example from the module forums.

// Get the course module id from a post or get request.
$id = required_param('id', PARAM_INT); 
// Get the course module. 
$cm = get_coursemodule_from_id('forum', $id, 0, false, MUST_EXIST)
// Get the current group id.
$currentgroupid = groups_get_activity_group($cm);
// Get the current group name from the group id.
$currentgroupname = groups_get_group_name($currentgroupid);
// Do as you please with your newly obtained group information.

How to make sure that the current user can see a given item in your module

For this example we are going to check to see if groups are active and whether the user has access to the discussion.

// Get the course module and discussion id from a post or get request.
$id           = required_param('id', PARAM_INT);
$discussionid = required_param('discussionid', PARAM_INT);
// Get the course module.
$cm = get_coursemodule_from_id('forum', $id, 0, false, MUST_EXIST);
// Get the group id for this discussion
$discussiongroup = $DB->get_record('forum_discussions', array('id' => $discussionid), groupid);
// Check access.
if (groups_get_activity_groupmode($cm)) {
    $groups = groups_get_activity_allowed_groups($cm);
} else {
    $groups = array();
if (! in_array($discussiongroup->groupid, array_keys($groups))) {
    print_error('groupnotamember', 'group');
// Continue on with group specific discussion

How to display a group menu

This will display a drop down box with a label of the current group visibility (seperate groups, visibile groups). It will also check to see what groups the user has access to and display the group options accordingly.

// Get the course module id from a post or get request
$id = required_param('id', PARAM_INT); 
// Get the course module
$cm = get_coursemodule_from_id('forum', $id, 0, false, MUST_EXIST); 
// Create a moodle_url. A URL is required so that if the user selects a different group, the page can be
// reloaded with the new groups information.
$url = new moodle_url('/mod/forum/view.php', array('id' => $cm->id));
// Print group information (A drop down box will be displayed if the user is a member of more than one group, 
// or has access to all groups). 
groups_print_activity_menu($cm, $url);

Further reading