guide WIP [skip ci]

docs/guide/README.md

@@ -33,9 +33,10 @@ Application Structure
 * [Entry Scripts](structure-entry-scripts.md)
 * [Applications](structure-applications.md)
 * [Application Components](structure-application-components.md)
-* [Controllers and Actions](structure-controllers.md)
+* [Controllers](structure-controllers.md)
 * [Views](structure-views.md)
 * [Models](structure-models.md)
+* **TBD** [Filters](structure-filters.md)
 * **TBD** [Widgets](structure-widgets.md)
 * **TBD** [Modules](structure-modules.md)
 * **TBD** [Extensions](structure-extensions.md)
@@ -50,7 +51,7 @@ Handling Requests
 * **TBD** [Responses](runtime-responses.md)
 * **TBD** [Sessions and Cookies](runtime-sessions-cookies.md)
 * [URL Parsing and Generation](runtime-url-handling.md)
-* **TBD** [Filtering](runtime-filtering.md)
+
 
 
 Key Concepts

docs/guide/structure-applications.md

@@ -217,7 +217,7 @@ specific controllers. In the following example, `account` will be mapped to
             'account' => 'app\controllers\UserController',
             'article' => [
                 'class' => 'app\controllers\PostController',
-                'pageTitle' => 'something new',
+                'enableCsrfValidation' => false,
             ],
         ],
     ],

docs/guide/structure-filters.md

+You may apply some action filters to controller actions to accomplish tasks such as determining
+who can access the current action, decorating the result of the action, etc.
+
+An action filter is an instance of a class extending [[yii\base\ActionFilter]].
+
+To use an action filter, attach it as a behavior to a controller or a module. The following
+example shows how to enable HTTP caching for the `index` action:
+
+```php
+public function behaviors()
+{
+    return [
+        'httpCache' => [
+            'class' => \yii\filters\HttpCache::className(),
+            'only' => ['index'],
+            'lastModified' => function ($action, $params) {
+                $q = new \yii\db\Query();
+                return $q->from('user')->max('updated_at');
+            },
+        ],
+    ];
+}
+```
+
+You may use multiple action filters at the same time. These filters will be applied in the
+order they are declared in `behaviors()`. If any of the filter cancels the action execution,
+the filters after it will be skipped.
+
+When you attach a filter to a controller, it can be applied to all actions of that controller;
+If you attach a filter to a module (or application), it can be applied to the actions of any controller
+within that module (or application).
+
+To create a new action filter, extend from [[yii\base\ActionFilter]] and override the
+[[yii\base\ActionFilter::beforeAction()|beforeAction()]] and [[yii\base\ActionFilter::afterAction()|afterAction()]]
+methods. The former will be executed before an action runs while the latter after an action runs.
+The return value of [[yii\base\ActionFilter::beforeAction()|beforeAction()]] determines whether
+an action should be executed or not. If `beforeAction()` of a filter returns false, the filters after this one
+will be skipped and the action will not be executed.
+
+The [authorization](authorization.md) section of this guide shows how to use the [[yii\filters\AccessControl]] filter,
+and the [caching](caching.md) section gives more details about the [[yii\filters\PageCache]] and [[yii\filters\HttpCache]] filters.
+These built-in filters are also good references when you learn to create your own filters.