ContentNegotiator

API reference › yii › filters › ContentNegotiator

class	`yii\filters\ContentNegotiator`
Extends	`yii\base\ActionFilter` » `yii\base\Behavior` » `yii\base\BaseObject`
Implements	`yii\base\BootstrapInterface`, `yii\base\Configurable`
Since	2.0
Source	`framework/filters/ContentNegotiator.php`

ContentNegotiator supports response format negotiation and application language negotiation.

When the supported formats property is specified, ContentNegotiator will support response format negotiation based on the value of the GET parameter $formatParam and the Accept HTTP header. If a match is found, the Response::$format property will be set as the chosen format. The Response::$acceptMimeType as well as Response::$acceptParams will also be updated accordingly.

When the supported languages is specified, ContentNegotiator will support application language negotiation based on the value of the GET parameter $languageParam and the Accept-Language HTTP header. If a match is found, the Application::$language property will be set as the chosen language.

You may use ContentNegotiator as a bootstrapping component as well as an action filter.

The following code shows how you can use ContentNegotiator as a bootstrapping component. Note that in this case, the content negotiation applies to the whole application.

// in application configuration
use yii\web\Response;

return [
    'bootstrap' => [
        [
            'class' => 'yii\filters\ContentNegotiator',
            'formats' => [
                'application/json' => Response::FORMAT_JSON,
                'application/xml' => Response::FORMAT_XML,
            ],
            'languages' => [
                'en',
                'de',
            ],
        ],
    ],
];

The following code shows how you can use ContentNegotiator as an action filter in either a controller or a module. In this case, the content negotiation result only applies to the corresponding controller or module, or even specific actions if you configure the only or except property of the filter.

use yii\web\Response;

public function behaviors()
{
    return [
        [
            'class' => 'yii\filters\ContentNegotiator',
            'only' => ['view', 'index'],  // in a controller
            // if in a module, use the following IDs for user actions
            // 'only' => ['user/view', 'user/index']
            'formats' => [
                'application/json' => Response::FORMAT_JSON,
            ],
            'languages' => [
                'en',
                'de',
            ],
        ],
    ];
}

Properties

Property	Type	Description	Defined by
`$except`	`array`	List of action IDs that this filter should not apply to. Default: `[]`.	`yii\base\ActionFilter`
`$formatParam`	`string`	The name of the GET parameter that specifies the response format. Default: `'_format'`.	`ContentNegotiator`
`$formats`	`array\|null`	List of supported response formats. Default: `null`.	`ContentNegotiator`
`$languageParam`	`string`	The name of the GET parameter that specifies the application language. Default: `'_lang'`.	`ContentNegotiator`
`$languages`	`array\|null`	A list of supported languages. Default: `null`.	`ContentNegotiator`
`$only`	`array`	List of action IDs that this filter should apply to. Default: `[]`.	`yii\base\ActionFilter`
`$owner`	`yii\base\T\|null`	The owner of this behavior Default: `null`.	`yii\base\Behavior`
`$request`	`yii\web\Request`	The current request. Default: `null`.	`ContentNegotiator`
`$response`	`yii\web\Response\|null`	The response to be sent. Default: `null`.	`ContentNegotiator`

Methods

Method	Description	Defined by
`__construct()`	Constructor.	`yii\base\BaseObject`
`__call()`	Calls the named method which is not a class method.	`yii\base\BaseObject`
`__get()`	Returns the value of an object property.	`yii\base\BaseObject`
`__isset()`	Checks if a property is set, i.e. defined and not null.	`yii\base\BaseObject`
`__set()`	Sets value of an object property.	`yii\base\BaseObject`
`__unset()`	Sets an object property to null.	`yii\base\BaseObject`
`afterAction()`	This method is invoked right after an action is executed.	`yii\base\ActionFilter`
`afterFilter()`		`yii\base\ActionFilter`
`attach()`	Attaches the behavior object to the component.	`yii\base\ActionFilter`
`beforeAction()`	This method is invoked right before an action is to be executed (after all possible filters.) You may override this method to do last-minute preparation for the action.	`ContentNegotiator`
`beforeFilter()`		`yii\base\ActionFilter`
`bootstrap()`	Bootstrap method to be called during application bootstrap stage.	`ContentNegotiator`
`canGetProperty()`	Returns a value indicating whether a property can be read.	`yii\base\BaseObject`
`canSetProperty()`	Returns a value indicating whether a property can be set.	`yii\base\BaseObject`
`className()` static	Returns the fully qualified name of this class.	`yii\base\BaseObject`
`detach()`	Detaches the behavior object from the component.	`yii\base\ActionFilter`
`events()`	Declares event handlers for the `$owner`’s events.	`yii\base\Behavior`
`hasMethod()`	Returns a value indicating whether a method is defined.	`yii\base\BaseObject`
`hasProperty()`	Returns a value indicating whether a property is defined.	`yii\base\BaseObject`
`init()`	Initializes the object.	`yii\base\BaseObject`
`negotiate()`	Negotiates the response format and application language.	`ContentNegotiator`
`getActionId()` protected	Returns an action ID by converting `Action::$uniqueId` into an ID relative to the module.	`yii\base\ActionFilter`
`isActive()` protected	Returns a value indicating whether the filter is active for the given action.	`yii\base\ActionFilter`
`isLanguageSupported()` protected	Returns a value indicating whether the requested language matches the supported language.	`ContentNegotiator`
`negotiateContentType()` protected	Negotiates the response format.	`ContentNegotiator`
`negotiateLanguage()` protected	Negotiates the application language.	`ContentNegotiator`

Property details

$formatParam

public string $formatParam = '_format'

The name of the GET parameter that specifies the response format.

Note that if the specified format does not exist in $formats, a NotAcceptableHttpException exception will be thrown. If the parameter value is empty or if this property is null, the response format will be determined based on the Accept HTTP header only.

$formats

public array|null $formats = null

List of supported response formats.

The keys are MIME types (e.g. application/json) while the values are the corresponding formats (e.g. html, json) which must be supported as declared in Response::$formatters.

If this property is empty or not set, response format negotiation will be skipped.

$languageParam

public string $languageParam = '_lang'

The name of the GET parameter that specifies the application language.

Note that if the specified language does not match any of $languages, the first language in $languages will be used. If the parameter value is empty or if this property is null, the application language will be determined based on the Accept-Language HTTP header only.

$languages

public array|null $languages = null

A list of supported languages.

The array keys are the supported language variants (e.g. en-GB, en-US), while the array values are the corresponding language codes (e.g. en, de) recognized by the application.

Array keys are not always required. When an array value does not have a key, the matching of the requested language will be based on a language fallback mechanism. For example, a value of en will match en, en_US, en-US, en-GB, etc.

If this property is empty or not set, language negotiation will be skipped.

$request

public yii\web\Request $request = null

The current request.

If not set, the request application component will be used.

$response

public yii\web\Response|null $response = null

The response to be sent.

If not set, the response application component will be used.

Method details

beforeAction()

public function beforeAction(mixed $action): bool

This method is invoked right before an action is to be executed (after all possible filters.) You may override this method to do last-minute preparation for the action.

Parameters

Parameter	Type	Description
`$action`	`mixed`	The action to be executed.

Returns

bool: Whether the action should continue to be executed.

bootstrap()

public function bootstrap(mixed $app): mixed

Bootstrap method to be called during application bootstrap stage.

Parameters

Parameter	Type	Description
`$app`	`mixed`	The application currently running

Returns

mixed

negotiate()

public function negotiate(): mixed

Negotiates the response format and application language.

Returns

mixed

isLanguageSupported()

protected function isLanguageSupported(string $requested, string $supported): bool

Returns a value indicating whether the requested language matches the supported language.

Parameters

Parameter	Type	Description
`$requested`	`string`	The requested language code
`$supported`	`string`	The supported language code

Returns

bool: Whether the requested language is supported

negotiateContentType()

protected function negotiateContentType(yii\web\Request $request, yii\web\Response $response): mixed

Negotiates the response format.

Parameters

Parameter	Type	Description
`$request`	`yii\web\Request`
`$response`	`yii\web\Response`

Returns

mixed

Throws

yii\web\BadRequestHttpException: if an array received for GET parameter $formatParam.
yii\web\NotAcceptableHttpException: if none of the requested content types is accepted.

negotiateLanguage()

protected function negotiateLanguage(yii\web\Request $request): string

Negotiates the application language.

Parameters

Parameter	Type	Description
`$request`	`yii\web\Request`

Returns

string: The chosen language