ZF Content Negotiation

Introduction

zf-content-negotiation is a module for automating content negotiation tasks within a Zend Framework application.

The following features are provided

• Mapping Accept header media types to specific view model types, and automatically casting controller results to those view model types.
• Defining Accept header media type whitelists; requests with Accept media types that fall outside the whitelist will be immediately rejected with a 406 Not Acceptable response.
• Defining Content-Type header media type whitelists; requests sending content bodies with Content-Type media types that fall outside the whitelist will be immediately rejected with a 415 Unsupported Media Type response.

Requirements

Please see the composer.json file.

Installation

Run the following composer command:

$ composer require zfcampus/zf-content-negotiation

Alternately, manually add the following to your composer.json, in the require section:

"require": {
    "zfcampus/zf-content-negotiation": "^1.2"
}

And then run composer update to ensure the module is installed.

Finally, add the module name to your project's config/application.config.php under the modules key:

return [
    /* ... */
    'modules' => [
        /* ... */
        'ZF\ContentNegotiation',
    ],
    /* ... */
];

zf-component-installer

If you use zf-component-installer, that plugin will install zf-content-negotiation as a module for you.

Configuration

User Configuration

The top-level configuration key for user configuration of this module is zf-content-negotiation.

Key: controllers

The controllers key is utilized for mapping a content negotiation strategy to a particular controller service name (from the top-level controllers section). The value portion of the controller array can either be a named selector (see selectors below), or a selector definition.

A selector definition consists of an array with the key of the array being the name of a view model, and the value of it being an indexed array of media types that, when matched, will select that view model.

Example:

'controllers' => [
    // Named selector:
    'Application\Controller\HelloWorld1' => 'Json',

    // Selector definition:
    'Application\Controller\HelloWorld2' => [
        'ZF\ContentNegotiation\JsonModel' => [
            'application/json',
            'application/*+json',
        ],
    ],
],

Key: selectors

The selectors key is utilized to create named selector definitions for reuse between many different controllers. The key part of the selectors array will be a name used to correlate the selector definition (which uses the format described in the controllers key).

Example:

'selectors' => [
    'Json' => [
        'ZF\ContentNegotiation\JsonModel' => [
            'application/json',
            'application/*+json',
        ],
    ],
],

A selector can contain multiple view models, each associated with different media types, allowing you to provide multiple representations. As an example, the following selector would allow a given controller to return either JSON or HTML output:

'selectors' => [
    'HTML-Json' => [
        'ZF\ContentNegotiation\JsonModel' => [
            'application/json',
            'application/*+json',
        ],
        'ZF\ContentNegotiation\ViewModel' => [
            'text/html',            
        ],
    ],
],

Key: accept_whitelist

The accept_whitelist key is utilized to instruct the content negotiation module which media types are acceptable for a given controller service name. When a controller service name is configured in this key, along with an indexed array of matching media types, only media types that match the Accept header of a given request will be allowed to be dispatched. Unmatched media types will receive a 406 Cannot honor Accept type specified response.

The value of each controller service name key can either be a string or an array of strings.

Example:

'accept_whitelist' => [
    'Application\\Controller\\HelloApiController' => [
        'application/vnd.application-hello+json',
        'application/hal+json',
        'application/json',
    ],
],

Key: content_type_whitelist

The content_type_whitelist key is utilized to instruct the content negotiation module which media types are valid for the Content-Type of a request. When a controller service name is configured in this key, along with an indexed array of matching media types, only media types that match the Content-Type header of a given request will be allowed to be dispatched. Unmatched media types will receive a 415 Invalid content-type specified response.

The value of each controller service name key can either be a string or an array of strings.

Example:

'content_type_whitelist' => [
    'Application\\Controller\\HelloWorldController' => [
        'application/vnd.application-hello-world+json',
        'application/json',
    ],
],

Key: x_http_method_override_enabled

• Since 1.3.0

This boolean flag determines whether or not the HttpMethodOverrideListener will be enabled by default.

Key: http_override_methods

• Since 1.3.0

The http_override_methods key is utilized to provide the HttpMethodOverrideListener with a map of allowed override methods for a given HTTP method, as specified via the X-HTTP-Method-Override header. Essentially, the values are:

'Incoming HTTP request method' => $arrayOfAllowedOverrideMethods,

As an example, if you want to allow the X-HTTP-Method-Override header to allow overriding HTTP GET requests with an alternate method, you might define this as follows:

'x_http_method_override_enabled' => true,
'http_override_methods' => [
    'GET' => [
        'HEAD',
        'POST',
        'PUT',
        'DELETE',
        'PATCH',
    ],
];

Then, to make a request, you could do the following:

GET /foo HTTP/1.1
Host: example.com
X-HTTP-Method-Override: PATCH

some=content&more=content

The above would then be interpreted as a PATCH request. If the same request were made via HTTP POST, or if a GET request were made with an override value of OPTIONS, the listener would raise a problem, as, in the former case, no maps are defined for POST, and, in the latter, OPTIONS is not in the map for GET.

System Configuration

The following configuration is provided in config/module.config.php to enable the module to function:

'filters' => [
    'aliases'   => [
        'Zend\Filter\File\RenameUpload' => 'filerenameupload',
    ],
    'factories' => [
        'filerenameupload' => Factory\RenameUploadFilterFactory::class,
    ],
],

'validators' => [
    'aliases'   => [
        'Zend\Validator\File\UploadFile' => 'fileuploadfile',
    ],
    'factories' => [
        'fileuploadfile' => Factory\UploadFileValidatorFactory::class,
    ],
],

'service_manager' => [
    'factories' => [
        ContentTypeListener::class        => InvokableFactory::class,
        'Request'                         => Factory\RequestFactory::class,
        AcceptListener::class             => Factory\AcceptListenerFactory::class,
        AcceptFilterListener::class       => Factory\AcceptFilterListenerFactory::class,
        ContentTypeFilterListener::class  => Factory\ContentTypeFilterListenerFactory::class,
        ContentNegotiationOptions::class  => Factory\ContentNegotiationOptionsFactory::class,
        HttpMethodOverrideListener::class => Factory\HttpMethodOverrideListenerFactory::class,
    ],
],

'controller_plugins' => [
    'aliases' => [
        'routeParam'  => ControllerPlugin\RouteParam::class,
        'queryParam'  => ControllerPlugin\QueryParam::class,
        'bodyParam'   => ControllerPlugin\BodyParam::class,
        'routeParams' => ControllerPlugin\RouteParams::class,
        'queryParams' => ControllerPlugin\QueryParams::class,
        'bodyParams'  => ControllerPlugin\BodyParams::class,
    ],
    'factories' => [
        ControllerPlugin\RouteParam::class  => InvokableFactory::class,
        ControllerPlugin\QueryParam::class  => InvokableFactory::class,
        ControllerPlugin\BodyParam::class   => InvokableFactory::class,
        ControllerPlugin\RouteParams::class => InvokableFactory::class,
        ControllerPlugin\QueryParams::class => InvokableFactory::class,
        ControllerPlugin\BodyParams::class  => InvokableFactory::class,
    ],
],

ZF Events

Listeners

ZF\ContentNegotiation\AcceptListener

This listener is attached to the MvcEvent::EVENT_DISPATCH event with priority -10. It is responsible for performing the actual selection and casting of a controller's view model based on the content negotiation configuration.

ZF\ContentNegotiation\ContentTypeListener

This listener is attached to the MvcEvent::EVENT_ROUTE event with a priority of -625. It is responsible for examining the Content-Type header in order to determine how the content body should be deserialized. Values are then persisted inside of a ParameterDataContainer which is stored in the ZFContentNegotiationParameterData key of the MvcEvent object.

ZF\ContentNegotiation\AcceptFilterListener

This listener is attached to the MvcEvent::EVENT_ROUTE event with a priority of -625. It is responsible for ensuring the controller selected by routing is configured to respond to the specific media type in the current request's Accept header. If it cannot, it will short-circuit the MVC dispatch process by returning a 406 Cannot honor Accept type specified response.

ZF\ContentNegotiation\ContentTypeFilterListener

This listener is attached to the MvcEvent::EVENT_ROUTE event with a priority of -625. It is responsible for ensuring the route matched controller can accept content in the request body specified by the media type in the current request's Content-Type header. If it cannot, it will short-circuit the MVC dispatch process by returning a 415 Invalid content-type specified response.

ZF\ContentNegotiation\HttpMethodOverrideListener

• Since 1.3.0

This listener is attached to the MvcEvent::EVENT_ROUTE event with a priority of -40, but only if the x_http_method_override_enabled configuration flag was toggle on. It is responsible for checking if an X-HTTP-Method-Override header is present, and, if so, if it contains a value in the set allowed for the current HTTP request method invoked. If so, it resets the HTTP request method to the header value.

ZF Services

Controller Plugins

ZF\ContentNegotiation\ControllerPlugin\RouteParam (a.k.a "routeParam")

A controller plugin (Zend\Mvc\Controller\AbstractActionController callable) that will return a single parameter with a particular name from the route match.

use Zend\Mvc\Controller\AbstractActionController;

class IndexController extends AbstractActionController
{
    public function indexAction()
    {
        return $this->routeParam('id', 'someDefaultValue');
    }
}

ZF\ContentNegotiation\ControllerPlugin\QueryParam (a.k.a "queryParam")

A controller plugin (Zend\Mvc\Controller\AbstractActionController callable) that will return a single parameter from the current request query string.

use Zend\Mvc\Controller\AbstractActionController;

class IndexController extends AbstractActionController
{
    public function indexAction()
    {
        return $this->queryParam('foo', 'someDefaultValue');
    }
}

ZF\ContentNegotiation\ControllerPlugin\BodyParam (a.k.a "bodyParam")

A controller plugin (Zend\Mvc\Controller\AbstractActionController callable) that will return a single parameter from the content-negotiated content body.

use Zend\Mvc\Controller\AbstractActionController;

class IndexController extends AbstractActionController
{
    public function indexAction()
    {
        return $this->bodyParam('foo', 'someDefaultValue');
    }
}

ZF\ContentNegotiation\ControllerPlugin\RouteParams (a.k.a "routeParams")

A controller plugin (Zend\Mvc\Controller\AbstractActionController callable) that will return a all the route parameters.

use Zend\Mvc\Controller\AbstractActionController;

class IndexController extends AbstractActionController
{
    public function indexAction()
    {
        return $this->routeParams()
    }
}

ZF\ContentNegotiation\ControllerPlugin\QueryParams (a.k.a "queryParams")

A controller plugin (Zend\Mvc\Controller\AbstractActionController callable) that will return a all the query parameters.

use Zend\Mvc\Controller\AbstractActionController;

class IndexController extends AbstractActionController
{
    public function indexAction()
    {
        return $this->queryParams()
    }
}

ZF\ContentNegotiation\ControllerPlugin\BodyParams (a.k.a "bodyParams")

A controller plugin (Zend\Mvc\Controller\AbstractActionController callable) that will return a all the content-negotiated body parameters.

use Zend\Mvc\Controller\AbstractActionController;

class IndexController extends AbstractActionController
{
    public function indexAction()
    {
        return $this->bodyParams()
    }
}