forum update calendar fix

Author: Syxton

mod/forumdates.php

@@ -67,4 +67,25 @@ public function validate_dates(cm_info $cm, array $dates) {
         }
         return $errors;
     }
+
+    public function save_dates(cm_info $cm, array $dates) {
+        global $DB, $COURSE, $CFG;
+        require_once($CFG->dirroot.'/mod/forum/locallib.php');
+
+        $forum = $DB->get_record('forum', ['id' => $cm->instance]);
+        $forum->id = $cm->instance;
+        $forum->duedate = $dates['duedate'];
+        $forum->cutoffdate = $dates['cutoffdate'];
+        if ($forum->assessed) {
+            $forum->assesstimestart = $dates['assesstimestart'];
+            $forum->assesstimefinish = $dates['assesstimefinish'];
+        }
+
+        $result = $DB->update_record('forum', $forum);
+        $forum->cmidnumber  = $cm->id;
+
+        // Update the calendar and grades.
+        forum_update_calendar($forum, $cm->id);
+        forum_grade_item_update($forum);
+    }
 }