Controller ========== Controller is one of the key parts of the application. It determines how to handle incoming request and creates a response. Most often a controller takes HTTP request data and returns HTML, JSON or XML as a response. Basics ------ Controller resides in application's `controllers` directory is is named like `SiteController.php` where `Site` part could be anything describing a set of actions it contains. The basic web controller is a class that extends [[\yii\web\Controller]] and could be very simple: ```php namespace app\controllers; use yii\web\Controller; class SiteController extends Controller { public function actionIndex() { // will render view from "views/site/index.php" return $this->render('index'); } public function actionTest() { // will just print "test" to the browser return 'test'; } } ``` As you can see, typical controller contains actions that are public class methods named as `actionSomething`. Routes ------ Each controller action has a corresponding internal route. In our example above `actionIndex` has `site/index` route and `actionTest` has `site/test` route. In this route `site` is referred to as controller ID while `test` is referred to as action ID. By default you can access specific controller and action using the `http://example.com/?r=controller/action` URL. This behavior is fully customizable. For details refer to [URL Management](url.md). If controller is located inside a module its action internal route will be `module/controller/action`. In case module, controller or action specified isn't found Yii will return "not found" page and HTTP status code 404. ### Defaults If user isn't specifying any route i.e. using URL like `http://example.com/`, Yii assumes that default route should be used. It is determined by [[\yii\web\Application::defaultRoute]] method and is `site` by default meaning that `SiteController` will be loaded. A controller has a default action. When the user request does not specify which action to execute by usign an URL such as `http://example.com/?r=site`, the default action will be executed. By default, the default action is named as `index`. It can be changed by setting the [[\yii\base\Controller::defaultAction]] property. Action parameters ----------------- It was already mentioned that a simple action is just a public method named as `actionSomething`. Now we'll review ways that an action can get parameters from HTTP. ### Action parameters You can define named arguments for an action and these will be automatically populated from corresponding values from `$_GET`. This is very convenient both because of the short syntax and an ability to specify defaults: ```php namespace app\controllers; use yii\web\Controller; class BlogController extends Controller { public function actionView($id, $version = null) { $post = Post::find($id); $text = $post->text; if($version) { $text = $post->getHistory($version); } return $this->render('view', array( 'post' => $post, 'text' => $text, )); } } ``` The action above can be accessed using either `http://example.com/?r=blog/view&id=42` or `http://example.com/?r=blog/view&id=42&version=3`. In the first case `version` isn't specified and default parameter value is used instead. ### Getting data from request If your action is working with data from HTTP POST or has too many GET parameters you can rely on request object that is accessible via `\Yii::$app->request`: ```php namespace app\controllers; use yii\web\Controller; use yii\web\HttpException; class BlogController extends Controller { public function actionUpdate($id) { $post = Post::find($id); if(!$post) { throw new HttpException(404); } if(\Yii::$app->request->isPost)) { $post->load($_POST); if($post->save()) { $this->redirect(array('view', 'id' => $post->id)); } } return $this->render('update', array( 'post' => $post, )); } } ``` Standalone actions ------------------ If action is generic enough it makes sense to implement it in a separate class to be able to reuse it. Create `actions/Page.php` ```php namespace \app\actions; class Page extends \yii\base\Action { public $view = 'index'; public function run() { $this->controller->render($view); } } ``` The following code is too simple to implement as a separate action but gives an idea of how it works. Action implemented can be used in your controller as following: ```php public SiteController extends \yii\web\Controller { public function actions() { return array( 'about' => array( 'class' => '@app/actions/Page', 'view' => 'about', ), ), ); } } ``` After doing so you can access your action as `http://example.com/?r=site/about`. Filters ------- Catching all incoming requests ------------------------------ See also -------- - [Console](console.md)