MDL-25660 recreate all workshop calendar events

Due to complex workshop upgrade path from 1.9 and missing calendar events
support in 2.x, the only safe way to get rid of potentially invalid
calendar events (such as those reported in MDL-26687) is to remove all
current workshop events and recreate them from scratch.

mod/workshop/db/upgrade.php

@@ -319,5 +319,42 @@ function xmldb_workshop_upgrade($oldversion) {
         upgrade_mod_savepoint(true, 2011061001, 'workshop');
     }
 
+    /**
+     * Remove all workshop calendar events
+     */
+    if ($oldversion < 2011061002) {
+        require_once($CFG->dirroot . '/calendar/lib.php');
+        $events = $DB->get_records('event', array('modulename' => 'workshop'));
+        foreach ($events as $event) {
+            $event = calendar_event::load($event);
+            $event->delete();
+        }
+        upgrade_mod_savepoint(true, 2011061002, 'workshop');
+    }
+
+    /**
+     * Recreate all workshop calendar events
+     */
+    if ($oldversion < 2011061003) {
+        require_once(dirname(dirname(__FILE__)) . '/lib.php');
+
+        $sql = "SELECT w.id, w.course, w.name, w.intro, w.introformat, w.submissionstart,
+                       w.submissionend, w.assessmentstart, w.assessmentend,
+                       cm.id AS cmid
+                  FROM {workshop} w
+                  JOIN {modules} m ON m.name = 'workshop'
+                  JOIN {course_modules} cm ON (cm.module = m.id AND cm.course = w.course AND cm.instance = w.id)";
+
+        $rs = $DB->get_recordset_sql($sql);
+
+        foreach ($rs as $workshop) {
+            $cmid = $workshop->cmid;
+            unset($workshop->cmid);
+            workshop_calendar_update($workshop, $cmid);
+        }
+        $rs->close();
+        upgrade_mod_savepoint(true, 2011061003, 'workshop');
+    }
+
     return true;
 }

mod/workshop/version.php

@@ -29,6 +29,6 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$module->version  = 2011061001;
+$module->version  = 2011061003;
 $module->requires = 2011020900;  // Requires this Moodle version
 //$module->cron     = 60;