Available Controllers

Controllers in the MVC layer simply need to be objects implementing Zend\Stdlib\DispatchableInterface. That interface describes a single method:

use Zend\Stdlib\DispatchableInterface;
use Zend\Stdlib\RequestInterface as Request;
use Zend\Stdlib\ResponseInterface as Response;

class Foo implements DispatchableInterface
{
    public function dispatch(Request $request, Response $response = null)
    {
        // ... do something, and preferably return a Response ...
    }
}

While this pattern is simple enough, chances are you don’t want to implement custom dispatch logic for every controller (particularly as it’s not unusual or uncommon for a single controller to handle several related types of requests).

The MVC also defines several interfaces that, when implemented, can provide controllers with additional capabilities.

Common Interfaces Used With Controllers

InjectApplicationEvent

The Zend\Mvc\InjectApplicationEventInterface hints to the Application instance that it should inject its MvcEvent into the controller itself. Why would this be useful?

Recall that the MvcEvent composes a number of objects: the Request and Response, naturally, but also the router, the route matches (a RouteMatch instance), and potentially the “result” of dispatching.

A controller that has the MvcEvent injected, then, can retrieve or inject these. As an example:

$matches = $this->getEvent()->getRouteMatch();
$id      = $matches->getParam('id', false);
if (!$id) {
    $response = $this->getResponse();
    $response->setStatusCode(500);
    $this->getEvent()->setResult('Invalid identifier; cannot complete request');
    return;
}

The InjectApplicationEventInterface defines simply two methods:

public function setEvent(Zend\EventManager\EventInterface $event);
public function getEvent();

ServiceLocatorAware

In most cases, you should define your controllers such that dependencies are injected by the application’s ServiceManager, via either constructor arguments or setter methods.

However, occasionally you may have objects you wish to use in your controller that are only valid for certain code paths. Examples include forms, paginators, navigation, etc. In these cases, you may decide that it doesn’t make sense to inject those objects every time the controller is used.

The ServiceLocatorAwareInterface interface hints to the ServiceManager that it should inject itself into the controller. It defines two simple methods:

use Zend\ServiceManager\ServiceLocatorInterface;
use Zend\ServiceManager\ServiceLocatorAwareInterface;

public function setServiceLocator(ServiceLocatorInterface $serviceLocator);
public function getServiceLocator();

EventManagerAware

Typically, it’s nice to be able to tie into a controller’s workflow without needing to extend it or hardcode behavior into it. The solution for this at the framework level is to use the EventManager.

You can hint to the ServiceManager that you want an EventManager injected by implementing the interface EventManagerAwareInterface, which tells the ServiceManager to inject an EventManager.

You define two methods. The first, a setter, should also set any EventManager identifiers you want to listen on, and the second, a getter, should simply return the composed EventManager instance.

use Zend\EventManager\EventManagerAwareInterface;
use Zend\EventManager\EventManagerInterface;

public function setEventManager(EventManagerInterface $events);
public function getEventManager();

Controller Plugins

Code re-use is a common goal for developers. Another common goal is convenience. However, this is often difficult to achieve cleanly in abstract, general systems.

Within your controllers, you’ll often find yourself repeating tasks from one controller to another. Some common examples:

• Generating URLs
• Redirecting
• Setting and retrieving flash messages (self-expiring session messages)
• Invoking and dispatching additional controllers

To facilitate these actions while also making them available to alternate controller implementations, we’ve created a PluginManager implementation for the controller layer, Zend\Mvc\Controller\PluginManager, building on the Zend\ServiceManager\AbstractPluginManager functionality. To utilize it, you simply need to implement the setPluginManager(PluginManager $plugins) method, and set up your code to use the controller-specific implementation by default:

use Zend\Mvc\Controller\PluginManager;

public function setPluginManager(PluginManager $plugins)
{
    $this->plugins = $plugins;
    $this->plugins->setController($this);

    return $this;
}

public function getPluginManager()
{
    if (!$this->plugins) {
        $this->setPluginManager(new PluginManager());
    }

    return $this->plugins;
}

public function plugin($name, array $options = null)
{
    return $this->getPluginManager()->get($name, $options);
}

The AbstractActionController

Implementing each of the above interfaces is a lesson in redundancy; you won’t often want to do it. As such, we’ve developed two abstract, base controllers you can extend to get started.

The first is Zend\Mvc\Controller\AbstractActionController. This controller implements each of the above interfaces, and uses the following assumptions:

• An “action” parameter is expected in the RouteMatch object composed in the attached MvcEvent. If none is found, a notFoundAction() is invoked.
• The “action” parameter is converted to a camelCased format and appended with the word “Action” to create a method name. As examples: “foo” maps to “fooAction”, “foo-bar” or “foo.bar” or “foo_bar” to “fooBarAction”. The controller then checks to see if that method exists. If not, the notFoundAction() method is invoked; otherwise, the discovered method is called.
• The results of executing the given action method are injected into the MvcEvent‘s “result” property (via setResult(), and accessible via getResult()).

Essentially, a route mapping to an AbstractActionController needs to return both “controller” and “action” keys in its matches.

Creation of action controllers is then reasonably trivial:

namespace Foo\Controller;

use Zend\Mvc\Controller\AbstractActionController;

class BarController extends AbstractActionController
{
    public function bazAction()
    {
        return array('title' => __METHOD__);
    }

    public function batAction()
    {
        return array('title' => __METHOD__);
    }
}

Interfaces and Collaborators

AbstractActionController implements each of the following interfaces:

• Zend\Stdlib\DispatchableInterface
• Zend\Mvc\InjectApplicationEventInterface
• Zend\ServiceManager\ServiceLocatorAwareInterface
• Zend\EventManager\EventManagerAwareInterface

The composed EventManager will be configured to listen on the following contexts:

• Zend\Stdlib\DispatchableInterface
• Zend\Mvc\Controller\AbstractActionController
• Zend\Mvc\Controller\AbstractController

Additionally, if you extend the class, it will listen on the extending class’s name.

The AbstractRestfulController

The second abstract controller ZF2 provides is Zend\Mvc\Controller\AbstractRestfulController. This controller provides a native RESTful implementation that simply maps HTTP request methods to controller methods, using the following matrix:

• GET maps to either get() or getList(), depending on whether or not an “id” parameter is found in the route matches. If one is, it is passed as an argument to get(); if not, getList() is invoked. In the former case, you should provide a representation of the given entity with that identification; in the latter, you should provide a list of entities.
• POST maps to create(). That method expects a $data argument, usually the $_POST superglobal array. The data should be used to create a new entity, and the response should typically be an HTTP 201 response with the Location header indicating the URI of the newly created entity and the response body providing the representation.
• PUT maps to update(), and requires that an “id” parameter exists in the route matches; that value is passed as an argument to the method. It should attempt to update the given entity, and, if successful, return either a 200 or 202 response status, as well as the representation of the entity.
• DELETE maps to delete(), and requires that an “id” parameter exists in the route matches; that value is passed as an argument to the method. It should attempt to delete the given entity, and, if successful, return either a 200 or 204 response status.

Additionally, you can map “action” methods to the AbstractRestfulController, just as you would in the AbstractActionController; these methods will be suffixed with “Action”, differentiating them from the RESTful methods listed above. This allows you to perform such actions as providing forms used to submit to the various RESTful methods, or to add RPC methods to your RESTful API.

Interfaces and Collaborators

AbstractRestfulController implements each of the following interfaces:

• Zend\Stdlib\DispatchableInterface
• Zend\Mvc\InjectApplicationEventInterface
• Zend\ServiceManager\ServiceLocatorAwareInterface
• Zend\EventManager\EventManagerAwareInterface

The composed EventManager will be configured to listen on the following contexts:

• Zend\Stdlib\DispatchableInterface
• Zend\Mvc\Controller\AbstractRestfulController
• Zend\Mvc\Controller\AbstractController

Additionally, if you extend the class, it will listen on the extending class’s name.