MDL-45579 group: Prevent duplicate enrolment keys in course groups

group/group_form.php

@@ -111,18 +111,31 @@ function validation($data, $files) {
                 }
             }
 
-            if (!empty($CFG->groupenrolmentkeypolicy) and $data['enrolmentkey'] != '' and $group->enrolmentkey !== $data['enrolmentkey']) {
-                // enforce password policy only if changing password
+            if ($data['enrolmentkey'] != '') {
                 $errmsg = '';
-                if (!check_password_policy($data['enrolmentkey'], $errmsg)) {
+                if (!empty($CFG->groupenrolmentkeypolicy) && $group->enrolmentkey !== $data['enrolmentkey']
+                        && !check_password_policy($data['enrolmentkey'], $errmsg)) {
+                    // Enforce password policy when the password is changed.
                     $errors['enrolmentkey'] = $errmsg;
+                } else {
+                    // Prevent twice the same enrolment key in course groups.
+                    $sql = "SELECT id FROM {groups} WHERE id <> :groupid AND courseid = :courseid AND enrolmentkey = :key";
+                    $params = array('groupid' => $data['id'], 'courseid' => $COURSE->id, 'key' => $data['enrolmentkey']);
+                    if ($DB->record_exists_sql($sql, $params)) {
+                        $errors['enrolmentkey'] = get_string('enrolmentkeyalreadyinuse', 'group');
+                    }
                 }
             }
 
         } else if (groups_get_group_by_name($COURSE->id, $name)) {
             $errors['name'] = get_string('groupnameexists', 'group', $name);
         } else if (!empty($idnumber) && groups_get_group_by_idnumber($COURSE->id, $idnumber)) {
             $errors['idnumber']= get_string('idnumbertaken');
+        } else if ($data['enrolmentkey'] != '') {
+            // Prevent twice the same enrolment key in course groups.
+            if ($DB->record_exists('groups', array('courseid' => $COURSE->id, 'enrolmentkey' => $data['enrolmentkey']))) {
+                $errors['enrolmentkey'] = get_string('enrolmentkeyalreadyinuse', 'group');
+            }
         }
 
         return $errors;

lang/en/group.php

@@ -61,6 +61,7 @@
 $string['enrolmentkey_help'] = 'An enrolment key enables access to the course to be restricted to only those who know the key. If a group enrolment key is specified, then not only will entering that key let the user into the course, but it will also automatically make them a member of this group.
 
 Note: Group enrolment keys must be enabled in the self enrolment settings and an enrolment key for the course must also be specified.';
+$string['enrolmentkeyalreadyinuse'] = 'This enrolment key is already used for another group.';
 $string['erroraddremoveuser'] = 'Error adding/removing user {$a} to group';
 $string['erroreditgroup'] = 'Error creating/updating group {$a}';
 $string['erroreditgrouping'] = 'Error creating/updating grouping {$a}';