# ViewAction

> ViewAction represents an action that displays a view according to a user-specified parameter.

[API reference](/docs/api/index.md) › [yii](/docs/api/yii/index.md) › [web](/docs/api/yii/web/index.md) › ViewAction

| class | `yii\web\ViewAction` |
| --- | --- |
| Extends | [`yii\base\Action`](/docs/api/yii/base/action/index.md) » [`yii\base\Component`](/docs/api/yii/base/component/index.md) » [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| Implements | [`yii\base\Configurable`](/docs/api/yii/base/configurable/index.md) |
| Since | 2.0 |
| Source | [`framework/web/ViewAction.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/web/ViewAction.php#L42) |

ViewAction represents an action that displays a view according to a user-specified parameter.

By default, the view being displayed is specified via the `view` GET parameter.

The name of the GET parameter can be customized via [`$viewParam`](/docs/api/yii/web/viewaction/index.md#property-viewParam).

Users specify a view in the format of `path/to/view`, which translates to the view name `ViewPrefix/path/to/view`
where `ViewPrefix` is given by [`$viewPrefix`](/docs/api/yii/web/viewaction/index.md#property-viewPrefix). The view will then be rendered by the
[render()](/docs/api/yii/base/controller/index.md#method-render) method of the currently active controller.

Note that the user-specified view name must start with a word character and can only contain word characters, forward
slashes, dots and dashes.

Not standalone-compatible: this action requires a hosting controller because rendering and layout resolution are
performed through the controller. Register it via [`Controller::actions()`](/docs/api/yii/base/controller/index.md#method-actions) rather than
[`Module::$actionMap`](/docs/api/yii/base/module/index.md#property-actionMap).

## Properties

| Property | Type | Description | Defined by |
| --- | --- | --- | --- |
| <span id="property-behaviors"></span>[`$behaviors`](/docs/api/yii/base/component/index.md#property-behaviors) read-only | `array<`[`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md)`<static>>` | List of behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="property-controller"></span>[`$controller`](/docs/api/yii/base/action/index.md#property-controller) | `yii\base\T\|null` | The controller that owns this action, or `null` when the action runs standalone. via [`Module::$actionMap`](/docs/api/yii/base/module/index.md#property-actionMap) Default: `null`. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| [`$defaultView`](#property-defaultView) | `string` | The name of the default view when [`ViewAction::$viewParam`](/docs/api/yii/web/viewaction/index.md#property-viewParam) GET parameter is not provided by user. Default: `'index'`. | `ViewAction` |
| <span id="property-id"></span>[`$id`](/docs/api/yii/base/action/index.md#property-id) | `string\|null` | ID of the action; `null` between construction and dispatcher post-assignment for standalone actions resolved through [`Module::$actionMap`](/docs/api/yii/base/module/index.md#property-actionMap) or [`Module::$actionNamespace`](/docs/api/yii/base/module/index.md#property-actionNamespace). Default: `null`. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| [`$layout`](#property-layout) | `mixed` | The name of the layout to be applied to the requested view. Default: `null`. | `ViewAction` |
| <span id="property-module"></span>[`$module`](/docs/api/yii/base/action/index.md#property-module) | [`yii\base\Module`](/docs/api/yii/base/module/index.md)`\|null` | The owning module, or `null` if neither a module nor a controller is attached. Available since 22.0. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="property-uniqueId"></span>[`$uniqueId`](/docs/api/yii/base/action/index.md#property-uniqueId) read-only | `string` | The unique ID of this action among the whole application. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="property-viewParam"></span>`$viewParam` | `string` | The name of the GET parameter that contains the requested view name. Default: `'view'`. | `ViewAction` |
| [`$viewPrefix`](#property-viewPrefix) | `string` | A string to be prefixed to the user-specified view name to form a complete view name. Default: `'pages'`. | `ViewAction` |

## Methods

| Method | Description | Defined by |
| --- | --- | --- |
| <span id="method-__construct"></span>[`__construct()`](/docs/api/yii/base/action/index.md#method-__construct) | Constructor. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="method-__call"></span>[`__call()`](/docs/api/yii/base/component/index.md#method-__call) | Calls the named method which is not a class method. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__clone"></span>[`__clone()`](/docs/api/yii/base/component/index.md#method-__clone) | This method is called after the object is created by cloning an existing one. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__get"></span>[`__get()`](/docs/api/yii/base/component/index.md#method-__get) | Returns the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__isset"></span>[`__isset()`](/docs/api/yii/base/component/index.md#method-__isset) | Checks if a property is set, i.e. defined and not null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__set"></span>[`__set()`](/docs/api/yii/base/component/index.md#method-__set) | Sets the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__unset"></span>[`__unset()`](/docs/api/yii/base/component/index.md#method-__unset) | Sets a component property to be null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-attachBehavior"></span>[`attachBehavior()`](/docs/api/yii/base/component/index.md#method-attachBehavior) | Attaches a behavior to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-attachBehaviors"></span>[`attachBehaviors()`](/docs/api/yii/base/component/index.md#method-attachBehaviors) | Attaches a list of behaviors to the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-behaviors"></span>[`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) | Returns a list of behaviors that this component should behave as. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-canGetProperty"></span>[`canGetProperty()`](/docs/api/yii/base/component/index.md#method-canGetProperty) | Returns a value indicating whether a property can be read. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-canSetProperty"></span>[`canSetProperty()`](/docs/api/yii/base/component/index.md#method-canSetProperty) | Returns a value indicating whether a property can be set. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-className"></span>[`className()`](/docs/api/yii/base/baseobject/index.md#method-className) static | Returns the fully qualified name of this class. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-detachBehavior"></span>[`detachBehavior()`](/docs/api/yii/base/component/index.md#method-detachBehavior) | Detaches a behavior from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-detachBehaviors"></span>[`detachBehaviors()`](/docs/api/yii/base/component/index.md#method-detachBehaviors) | Detaches all behaviors from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-ensureBehaviors"></span>[`ensureBehaviors()`](/docs/api/yii/base/component/index.md#method-ensureBehaviors) | Makes sure that the behaviors declared in [`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) are attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getBehavior"></span>[`getBehavior()`](/docs/api/yii/base/component/index.md#method-getBehavior) | Returns the named behavior object. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getBehaviors"></span>[`getBehaviors()`](/docs/api/yii/base/component/index.md#method-getBehaviors) | Returns all behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getModule"></span>[`getModule()`](/docs/api/yii/base/action/index.md#method-getModule) | Returns the module that owns this action when invoked standalone. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="method-getUniqueId"></span>[`getUniqueId()`](/docs/api/yii/base/action/index.md#method-getUniqueId) | Returns the unique ID of this action among the whole application. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="method-hasEventHandlers"></span>[`hasEventHandlers()`](/docs/api/yii/base/component/index.md#method-hasEventHandlers) | Returns a value indicating whether there is any handler attached to the named event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasMethod"></span>[`hasMethod()`](/docs/api/yii/base/component/index.md#method-hasMethod) | Returns a value indicating whether a method is defined. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasProperty"></span>[`hasProperty()`](/docs/api/yii/base/component/index.md#method-hasProperty) | Returns a value indicating whether a property is defined for this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-init"></span>[`init()`](/docs/api/yii/base/baseobject/index.md#method-init) | Initializes the object. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-off"></span>[`off()`](/docs/api/yii/base/component/index.md#method-off) | Detaches an existing event handler from this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-on"></span>[`on()`](/docs/api/yii/base/component/index.md#method-on) | Attaches an event handler to an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`run()`](#method-run) | Runs the action. | `ViewAction` |
| <span id="method-runWithParams"></span>[`runWithParams()`](/docs/api/yii/base/action/index.md#method-runWithParams) | Runs this action with the specified parameters. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="method-setModule"></span>[`setModule()`](/docs/api/yii/base/action/index.md#method-setModule) | Sets the module that owns this action when invoked standalone. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="method-trigger"></span>[`trigger()`](/docs/api/yii/base/component/index.md#method-trigger) | Triggers an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-afterRun"></span>[`afterRun()`](/docs/api/yii/base/action/index.md#method-afterRun) protected | This method is called right after `run()` is executed. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="method-beforeRun"></span>[`beforeRun()`](/docs/api/yii/base/action/index.md#method-beforeRun) protected | This method is called right before `run()` is executed. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| [`render()`](#method-render) protected | Renders a view. | `ViewAction` |
| <span id="method-resolveStandaloneParams"></span>[`resolveStandaloneParams()`](/docs/api/yii/base/action/index.md#method-resolveStandaloneParams) protected | Resolves typed parameters of `run()` when the action is invoked without a hosting controller. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| [`resolveViewName()`](#method-resolveViewName) protected | Resolves the view name currently being requested. | `ViewAction` |

## Property details

### $defaultView <span id="property-defaultView"></span>

```php
public string $defaultView = 'index'
```

The name of the default view when [`ViewAction::$viewParam`](/docs/api/yii/web/viewaction/index.md#property-viewParam) GET parameter is not provided by user.

Defaults to 'index'. This should be in the format of 'path/to/view', similar to that given in the
GET parameter.

### $layout <span id="property-layout"></span>

```php
public mixed $layout = null
```

The name of the layout to be applied to the requested view.

This will be assigned to [`Controller::$layout`](/docs/api/yii/base/controller/index.md#property-layout) before the view is rendered.
Defaults to null, meaning the controller's layout will be used.
If false, no layout will be applied.

### $viewPrefix <span id="property-viewPrefix"></span>

```php
public string $viewPrefix = 'pages'
```

A string to be prefixed to the user-specified view name to form a complete view name.

For example, if a user requests for `tutorial/chap1`, the corresponding view name will
be `pages/tutorial/chap1`, assuming the prefix is `pages`.
The actual view file is determined by [`View::findViewFile()`](/docs/api/yii/base/view/index.md#method-findViewFile).

## Method details

### run() <span id="method-run"></span>

```php
public function run(): mixed
```

Runs the action.

This method displays the view requested by the user.

**Returns**

`mixed`

**Throws**

- [`NotFoundHttpException`](/docs/api/yii/web/notfoundhttpexception/index.md): if the view file cannot be found

### render() <span id="method-render"></span>

```php
protected function render(string $viewName): string
```

Renders a view.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$viewName` | `string` | View name |

**Returns**

`string`: Result of the rendering

### resolveViewName() <span id="method-resolveViewName"></span>

```php
protected function resolveViewName(): string
```

Resolves the view name currently being requested.

**Returns**

`string`: The resolved view name

**Throws**

- [`NotFoundHttpException`](/docs/api/yii/web/notfoundhttpexception/index.md): if the specified view name is invalid