Zend Framework 2: Auto disable layout for ajax calls

Question

An AJAX request to one of my controller actions currently returns the full page HTML.

I only want it to return the HTML (.phtml contents) for that particular action.

The following code poorly solves the problem by manually disabling the layout for the particular action:

    $viewModel = new ViewModel();
    $viewModel->setTerminal(true);
    return $viewModel;

How can I make my application automatically disable the layout when an AJAX request is detected? Do I need to write a custom strategy for this? Any advice on how to do this is much appreciated.

Additionally, I've tried the following code in my app Module.php - it is detecting AJAX correctly but the setTerminal() is not disabling the layout.

public function onBootstrap(EventInterface $e)
{
    $application = $e->getApplication();
    $application->getEventManager()->attach('route', array($this, 'setLayout'), 100);

    $this->setApplication($application);

    $this->initPhpSettings($e);
    $this->initSession($e);
    $this->initTranslator($e);
    $this->initAppDi($e);
}

public function setLayout(EventInterface $e)
{
    $request = $e->getRequest();
    $server  = $request->getServer();

    if ($request->isXmlHttpRequest()) {
        $view_model = $e->getViewModel();
        $view_model->setTerminal(true);
    }
}

Thoughts?

Answer 1

Indeed the best thing would be to write another Strategy. There is a JsonStrategy which can auto-detect the accept header to automatically return Json-Format, but as with Ajax-Calls for fullpages, there it's good that it doesn't automatically do things, because you MAY want to get a full page. Above mentioned solution you mentioned would be the quick way to go.

When going for full speed, you'd only have one additional line. It's a best practice to always return fully qualified ViewModels from within your controller. Like:

public function indexAction() 
{
    $request   = $this->getRequest();
    $viewModel = new ViewModel();
    $viewModel->setTemplate('module/controller/action');
    $viewModel->setTerminal($request->isXmlHttpRequest());

    return $viewModel->setVariables(array(
         //list of vars
    ));
}

Answer 2

I think the problem is that you're calling setTerminal() on the view model $e->getViewModel() that is responsible for rendering the layout, not the action. You'll have to create a new view model, call setTerminal(true), and return it. I use a dedicated ajax controller so there's no need of determining whether the action is ajax or not:

use Zend\View\Model\ViewModel;
use Zend\Mvc\MvcEvent;
use Zend\Mvc\Controller\AbstractActionController;

class AjaxController extends AbstractActionController
{
    protected $viewModel;

    public function onDispatch(MvcEvent $mvcEvent)
    {
        $this->viewModel = new ViewModel; // Don't use $mvcEvent->getViewModel()!
        $this->viewModel->setTemplate('ajax/response');
        $this->viewModel->setTerminal(true); // Layout won't be rendered

        return parent::onDispatch($mvcEvent);
    }

    public function someAjaxAction()
    {
        $this->viewModel->setVariable('response', 'success');

        return $this->viewModel;
    }
}

and in ajax/response.phtml simply the following:

<?= $this->response ?>