diff --git a/grade/report/user/externallib.php b/grade/report/user/externallib.php
index da5f8668631..4988d2a6680 100644
--- a/grade/report/user/externallib.php
+++ b/grade/report/user/externallib.php
@@ -165,6 +165,7 @@ class gradereport_user_external extends external_api {
                 'courseid'      => $course->id,
                 'userid'        => $user->id,
                 'userfullname'  => fullname($user),
+                'useridnumber'  => $user->idnumber,
                 'maxdepth'      => $report->maxdepth,
             );
             if ($tabledata) {
@@ -191,6 +192,7 @@ class gradereport_user_external extends external_api {
                     'courseid'      => $course->id,
                     'userid'        => $currentuser->id,
                     'userfullname'  => fullname($currentuser),
+                    'useridnumber'  => $currentuser->idnumber,
                     'maxdepth'      => $report->maxdepth,
                 );
                 if ($tabledata) {
@@ -478,6 +480,7 @@ class gradereport_user_external extends external_api {
                             'courseid' => new external_value(PARAM_INT, 'course id'),
                             'userid'   => new external_value(PARAM_INT, 'user id'),
                             'userfullname' => new external_value(PARAM_TEXT, 'user fullname'),
+                            'useridnumber' => new external_value(PARAM_TEXT, 'user idnumber'),
                             'maxdepth'   => new external_value(PARAM_INT, 'table max depth (needed for printing it)'),
                             'gradeitems' => new external_multiple_structure(
                                 new external_single_structure(
@@ -488,6 +491,7 @@ class gradereport_user_external extends external_api {
                                         'itemmodule' => new external_value(PARAM_PLUGIN, 'Grade item module'),
                                         'iteminstance' => new external_value(PARAM_INT, 'Grade item instance'),
                                         'itemnumber' => new external_value(PARAM_INT, 'Grade item item number'),
+                                        'idnumber' => new external_value(PARAM_TEXT, 'Grade item idnumber'),
                                         'categoryid' => new external_value(PARAM_INT, 'Grade item category id'),
                                         'outcomeid' => new external_value(PARAM_INT, 'Outcome id'),
                                         'scaleid' => new external_value(PARAM_INT, 'Scale id'),
diff --git a/grade/report/user/lib.php b/grade/report/user/lib.php
index 7290b184898..98593b8497f 100644
--- a/grade/report/user/lib.php
+++ b/grade/report/user/lib.php
@@ -517,6 +517,7 @@ class grade_report_user extends grade_report {
                 $gradeitemdata['itemmodule'] = $grade_object->itemmodule;
                 $gradeitemdata['iteminstance'] = $grade_object->iteminstance;
                 $gradeitemdata['itemnumber'] = $grade_object->itemnumber;
+                $gradeitemdata['idnumber'] = $grade_object->idnumber;
                 $gradeitemdata['categoryid'] = $grade_object->categoryid;
                 $gradeitemdata['outcomeid'] = $grade_object->outcomeid;
                 $gradeitemdata['scaleid'] = $grade_object->outcomeid;
diff --git a/grade/report/user/tests/externallib_test.php b/grade/report/user/tests/externallib_test.php
index 6057a386ba7..b781d42c9ed 100644
--- a/grade/report/user/tests/externallib_test.php
+++ b/grade/report/user/tests/externallib_test.php
@@ -52,7 +52,7 @@ class gradereport_user_externallib_testcase extends externallib_advanced_testcas
         $course = $this->getDataGenerator()->create_course(array('groupmode' => SEPARATEGROUPS, 'groupmodeforce' => 1));
 
         $studentrole = $DB->get_record('role', array('shortname' => 'student'));
-        $student1 = $this->getDataGenerator()->create_user();
+        $student1 = $this->getDataGenerator()->create_user(array('idnumber' => 'testidnumber'));
         $this->getDataGenerator()->enrol_user($student1->id, $course->id, $studentrole->id);
 
         $student2 = $this->getDataGenerator()->create_user();
@@ -76,8 +76,8 @@ class gradereport_user_externallib_testcase extends externallib_advanced_testcas
         $modcontext = get_coursemodule_from_instance('assign', $assignment->id, $course->id);
         $assignment->cmidnumber = $modcontext->id;
 
-        $student1grade = array('userid' => $student1->id, 'rawgrade' => $s1grade);
-        $student2grade = array('userid' => $student2->id, 'rawgrade' => $s2grade);
+        $student1grade = array('userid' => $student1->id, 'rawgrade' => $s1grade, 'idnumber' => 'testidnumber1');
+        $student2grade = array('userid' => $student2->id, 'rawgrade' => $s2grade, 'idnumber' => 'testidnumber2');
         $studentgrades = array($student1->id => $student1grade, $student2->id => $student2grade);
         assign_grade_item_update($assignment, $studentgrades);
 
@@ -347,6 +347,7 @@ class gradereport_user_externallib_testcase extends externallib_advanced_testcas
 
         $this->assertEquals($course->id, $studentgrades['usergrades'][0]['courseid']);
         $this->assertEquals($student1->id, $studentgrades['usergrades'][0]['userid']);
+        $this->assertEquals($student1->idnumber, $studentgrades['usergrades'][0]['useridnumber']);
         $this->assertEquals($assignment->name, $studentgrades['usergrades'][0]['gradeitems'][0]['itemname']);
         $this->assertEquals('mod', $studentgrades['usergrades'][0]['gradeitems'][0]['itemtype']);
         $this->assertEquals('assign', $studentgrades['usergrades'][0]['gradeitems'][0]['itemmodule']);
@@ -373,6 +374,10 @@ class gradereport_user_externallib_testcase extends externallib_advanced_testcas
         $this->assertEquals(2, $studentgrades['usergrades'][0]['gradeitems'][0]['numusers']);
         $this->assertEquals(70, $studentgrades['usergrades'][0]['gradeitems'][0]['averageformatted']);
 
+        // Check that the idnumber for assignment grades is equal to the cmid.
+        $this->assertEquals((string) $studentgrades['usergrades'][0]['gradeitems'][0]['cmid'],
+            $studentgrades['usergrades'][0]['gradeitems'][0]['idnumber']);
+
         // Hide one grade for the user.
         $gradegrade = new grade_grade(array('userid' => $student1->id,
                                         'itemid' => $studentgrades['usergrades'][0]['gradeitems'][0]['id']), true);