Get request parameters in controller's constructor Zend Framework 2

Question

I have 10 actions in one Controller. Every action required ID from request. I want to check ID in constructor for every action, so I want avoid to write the same code 10 times in every action.

obviously, In constructor I can not use functions like:

$this->params()->fromQuery('paramname'); or 
$this->params()->fromRoute('paramname');

So, the question is how to get request params in controller's constructor?

Answer 1

Short answer: you cannot. The plugins (you are using params here) are available after construct, unfortunately.

There are two ways to make your code DRY: extract a method and perform extraction with the event system.

Extract method: the most simple one:

class MyController
{
    public function fooAction()
    {
        $id = $this->getId();

        // Do something with $id
    }

    public function barAction()
    {
        $id = $this->getId();

        // Do something with $id
    }

    protected function getId()
    {
        return $this->params('id');
    }
}

Or if you want to hydrate the parameter directly, this is how I do this quite often:

class MyController
{
    protected $repository;

    public function __construct(Repository $repository)
    {
        $this->repository = repository;
    }

    public function barAction()
    {
        $foo = $this->getFoo();

        // Do something with $foo
    }

    public function bazAction()
    {
        $foo = $this->getFoo();

        // Do something with $foo
    }

    protected function getFoo()
    {
        $id  = $this->params('id');
        $foo = $this->repository->find($id);

        if (null === $foo) {
            throw new FooNotFoundException(sprintf(
            'Cannot find a Foo with id %s', $id
            ));
        }

        return $foo;
    }
}

With the event sytem: you hook into the dispatch event to grab the id and set it prior to execution of the action:

class MyController
{
    protected $id;

    public function fooAction()
    {
        // Use $this->id
    }

    public function barAction()
    {
        // Use $this->id
    }

    protected function attachDefaultListeners()
    {
        parent::attachDefaultListeners();

        $events = $this->getEventManager();
        $events->attach(MvcEvent::EVENT_DISPATCH, array($this, 'loadId'), 100);
    }

    public function loadId()
    {
        $this->id = $this->params('id');
    }
}

This feature works as upon dispatch, the loadId() method is executed and then the other (fooAction/barAction) method is ran.