The Observer System

Like many applications, Wolf CMS has an event/observer system. We call it the observer system because Observers watch for events. Most usually, the observers are used by plugins but they can be found in other parts of the Wolf CMS system.

Watching for events

In order to watch for an event and subsequently initiate some action, you first tell the Observer system you want to observe an event, then you write a handler function.

  Observer::observe('page_edit_after_save', 'my_simple_observer');

  function my_simple_observer($page) {
      /* do what you want to do */
      var_dump($page);
  }

The first call to Observer::observe tells Wolf CMS that your plugin wants to receive events of the type page_edit_after_save and that the function that should handle these types of events is called my_simple_observer.

Generating an event

Not only can you observe events that are generated, you can of course also generate events yourself.

  Observer::notify('my_plugin_event', $somevar);

As you can see, the code to generate an event is fairly simple. The first argument, my_plugin_event, is the event's name. The second argument is a variable that is passed to the handling function. This variable can contain just about anything you want, from a simple string to an array of complex objects.

Using Observers to customize Page form

Observer events in the Page editing form allow you to include custom inputs or dialogs to save data that is not part of the page model. The following diagram gives you an indication of which event you should use and where it would be applied within the form.

Overview of Observer events

The Wolf CMS Observer system has a number of events which will continue to expand in the future. The following is a list of events with their parameters:

  Observer::notify('admin_after_logout', $username);
  Observer::notify('admin_login_failed', $data['username']);
  Observer::notify('admin_login_success', $data['username']);

  Observer::notify('comment_after_add', $comment);
  Observer::notify('comment_after_approve', $comment);
  Observer::notify('comment_after_delete', $comment);
  Observer::notify('comment_after_edit', $comment);
  Observer::notify('comment_after_unapprove', $comment);

  Observer::notify('cron_run');

  Observer::notify('csrf_token_invalid', AuthUser::getUserName()); // Since 0.7.0
  Observer::notify('csrf_token_not_found', AuthUser::getUserName()); // Since 0.7.0

  Observer::notify('dispatch_route_found', $uri);

  Observer::notify('layout_after_add', $layout);
  Observer::notify('layout_after_delete', $layout);
  Observer::notify('layout_after_edit', $layout);

  Observer::notify('login_requested', $redirect); // Since 0.7.5
  Observer::notify('login_required', $redirect); // Since 0.7.5
  Observer::notify('logout_requested'); // Since 0.7.0

  Observer::notify('page_add_before_save', $page); // Added in Rev251 for 0.7.0
  Observer::notify('page_add_after_save', $page);
  Observer::notify('page_before_execute_layout', $layout); // Param. since 0.7.6
  Observer::notify('page_delete', $page);
  Observer::notify('page_edit_before_save', $page); // Added in Rev251 for 0.7.0
  Observer::notify('page_edit_after_save', $page);
  Observer::notify('page_found', $page);
  Observer::notify('page_not_found', $uri); // $uri parameter as of 0.8.0
  Observer::notify('page_requested', $uri);

  Observer::notify('part_add_before_save', $part); // Since 0.7.0
  Observer::notify('part_add_after_save', $part); // Since 0.7.0
  Observer::notify('part_edit_after_save', $part); // Since 0.7.0
  Observer::notify('part_edit_before_save', $part); // Since 0.7.0

  Observer::notify('plugin_after_disable', $plugin);
  Observer::notify('plugin_after_enable', $plugin);
  Observer::notify('plugin_after_uninstall', $plugin);

  Observer::notify('snippet_after_add', $snippet);
  Observer::notify('snippet_after_delete', $snippet);
  Observer::notify('snippet_after_edit', $snippet);

  Observer::notify('user_after_add', $user->name, $user->id); // id since 0.7.6
  Observer::notify('user_after_delete', $user->name, $user->id); // id since 0.7.6
  Observer::notify('user_after_edit', $user->name, $user->id); // id since 0.7.6
  Observer::notify('user_edit_view_after_details', $user); // Since 0.7.0

  Observer::notify('view_backend_list_plugin', $plugin_name, $plugin);
  Observer::notify('view_backend_layout_head', CURRENT_PATH); // 0.7.7-dev

  Observer::notify('view_page_edit_plugins', $page);
  Observer::notify('view_page_edit_tab_links', $page); // Added in for 0.7.4
  Observer::notify('view_page_edit_popup', $page);
  Observer::notify('view_page_edit_tabs', $page);
  Observer::notify('view_page_after_edit_tabs', $page);