# Action

> Base class for HTTP standalone actions dispatched without a hosting controller.

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

| class | `yii\web\Action` |
| --- | --- |
| 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 | 22.0 |
| Source | [`framework/web/Action.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/web/Action.php#L50) |

2 subclasses:

- [`yii\debug\actions\Action`](/docs/extensions/debug/reference/actions/action/index.md)
- [`yii\debug\actions\IdentityAction`](/docs/extensions/debug/reference/actions/identityaction/index.md)

Base class for HTTP standalone actions dispatched without a hosting controller.

Use this class instead of [`Action`](/docs/api/yii/base/action/index.md) when an action handles an HTTP request and should benefit from the
same parameter-binding semantics as web controller actions: scalar coercion, [`BadRequestHttpException`](/docs/api/yii/web/badrequesthttpexception/index.md) on type
mismatches and missing required parameters, and DI resolution of typed services through module components,
module DI definitions, and the global container.

Standalone actions extending [`Action`](/docs/api/yii/base/action/index.md) still receive DI-based parameter resolution, but skip the
HTTP-specific scalar filtering and exception mapping. Reserve that base class for non-HTTP contexts (console actions,
queue jobs, scheduled tasks).

Usage example:

```php
namespace app\controllers;

use yii\web\Action;
use yii\web\Response;

final class HealthAction extends Action
{
    public function run(int $id, Response $response): Response
    {
        // 'abc' for $id throws BadRequestHttpException, '7' is coerced to int 7.
        return $response;
    }
}
```

## 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::$actionMap`](/docs/api/yii/base/module/index.md#property-actionMap) Default: `null`. | [`yii\base\Action`](/docs/api/yii/base/action/index.md) |
| <span id="property-id"></span>[`$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) |
| <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) |

## 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) |
| <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) |
| [`resolveStandaloneParams()`](#method-resolveStandaloneParams) protected | Resolves the parameters of `run()` using the same HTTP-aware binder as [`Controller::bindActionParams()`](/docs/api/yii/web/controller/index.md#method-bindActionParams). | `Action` |

## Method details

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

```php
protected function resolveStandaloneParams(array $params): array
```

Resolves the parameters of `run()` using the same HTTP-aware binder as [`Controller::bindActionParams()`](/docs/api/yii/web/controller/index.md#method-bindActionParams).

Delegates to [`Controller::bindActionParamsToCallable()`](/docs/api/yii/web/controller/index.md#method-bindActionParamsToCallable) so scalar parameters are coerced and validated,
required parameters raise [`BadRequestHttpException`](/docs/api/yii/web/badrequesthttpexception/index.md), and typed services are autowired from the module and
the global container.

Populates [`Application::$requestedParams`](/docs/api/yii/base/application/index.md#property-requestedParams) with the merged action and injected parameter descriptions,
mirroring the controller-bound dispatch.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$params` | `array` | Route parameters to be bound to `\yii\web\run()`. |

**Returns**

`array`: The positional argument list for the action's `\yii\web\run()` method.