Fixing Chat event type + handling illegal eventtype displaying

Without this fix, chat created events with eventtype set to boolean.
Such value was then used by calendar block to get a string, which
now produces coding_exception.

calendar/lib.php

@@ -501,7 +501,12 @@ function calendar_add_event_metadata($event) {
         }
 
         $modulename = get_string('modulename', $event->modulename);
-        $eventtype = get_string($event->eventtype, $event->modulename);
+        if (get_string_manager()->string_exists($event->eventtype, $event->modulename)) {
+            // will be used as alt text if the event icon
+            $eventtype = get_string($event->eventtype, $event->modulename);
+        } else {
+            $eventtype = '';
+        }
         $icon = $OUTPUT->pix_url('icon', $event->modulename) . '';
 
         $event->icon = '<img height="16" width="16" src="'.$icon.'" alt="'.$eventtype.'" title="'.$modulename.'" style="vertical-align: middle;" />';

lib/moodlelib.php

@@ -5968,6 +5968,10 @@ class core_string_manager implements string_manager {
      * @return boot true if exists
      */
     public function string_exists($identifier, $component) {
+       $identifier = clean_param($identifier, PARAM_STRINGID);
+        if (empty($identifier)) {
+            return false;
+        }
         $lang = current_language();
         $string = $this->load_component_strings($component, $lang);
         return isset($string[$identifier]);
@@ -6293,6 +6297,10 @@ class install_string_manager implements string_manager {
      * @return boot true if exists
      */
     public function string_exists($identifier, $component) {
+        $identifier = clean_param($identifier, PARAM_STRINGID);
+        if (empty($identifier)) {
+            return false;
+        }
         // simple old style hack ;)
         $str = get_string($identifier, $component);
         return (strpos($str, '[[') === false);

mod/chat/lib.php

@@ -120,7 +120,7 @@ function chat_add_instance($chat) {
         $event->userid      = 0;
         $event->modulename  = 'chat';
         $event->instance    = $returnid;
-        $event->eventtype   = $chat->schedule;
+        $event->eventtype   = 'chattime';
         $event->timestart   = $chat->chattime;
         $event->timeduration = 0;
 
@@ -499,7 +499,7 @@ function chat_refresh_events($courseid = 0) {
             $event->userid      = 0;
             $event->modulename  = 'chat';
             $event->instance    = $chat->id;
-            $event->eventtype   = $chat->schedule;
+            $event->eventtype   = 'chattime';
             $event->timeduration = 0;
             $event->visible     = $DB->get_field('course_modules', 'visible', array('module'=>$moduleid, 'instance'=>$chat->id));
 

mod/choice/mod_form.php

@@ -33,7 +33,7 @@ class mod_choice_mod_form extends moodleform_mod {
         $menuoptions[1] = get_string('enable');
         $mform->addElement('header', 'timerestricthdr', get_string('limit', 'choice'));
         $mform->addElement('select', 'limitanswers', get_string('limitanswers', 'choice'), $menuoptions);
-        $mform->setHelpButton('limitanswers', array('limit', get_string('limit', 'choice'), 'choice'));
+        $mform->addHelpButton('limitanswers', 'choice');
 
         if ($this->_instance){
             $repeatno = $DB->count_records('choice_options', array('choiceid'=>$this->_instance));