Prevent Calendarevent value being set when disabled at site level.

classes/structure.php

@@ -454,13 +454,18 @@ class mod_attendance_structure {
     public function add_sessions($sessions) {
         global $DB;
 
+        $config = get_config('attendance');
+
         foreach ($sessions as $sess) {
             $sess->attendanceid = $this->id;
             $sess->automarkcompleted = 0;
             if (!isset($sess->automark)) {
                 $sess->automark = 0;
             }
-
+            if (empty($config->enablecalendar)) {
+                // If calendard disabled at site level, don't use it.
+                $sess->calendarevent = 0;
+            }
             $sess->id = $DB->insert_record('attendance_sessions', $sess);
             $description = file_save_draft_area_files($sess->descriptionitemid,
                 $this->context->id, 'mod_attendance', 'session', $sess->id,