Yii2 Bootstrap 3
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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.
> Note: If controller name or action name contains camelCased words, internal route will use dashes i.e. for
`DateTimeController::actionFastForward` route will be `date-time/fast-forward`.
### 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)