README

Bridges between Drupal 8 and PSR-15 middleware modules through the use of Zend Framework's Stratigility.

Version 1.0 allows you to use PSR-15 middlewares in Drupal 8. Versions 0.x are bridges with the now deprecated http-interop middlewares.

Installation

This project is a Drupal 8 module.

The recommended way to install drupal-stratigility-bridge is through Composer:

composer require thecodingmachine/drupal-stratigility-bridge

Usage

This module will fill the Drupal container with a new stratigility_pipe entry (it is a Zend\Stratigility\MiddlewarePipe).

You can extend this entry in your own module to register a new middleware.

In Drupal services, you can simply add the psr15_middleware to your middleware service. This will automatically register the middleware in Stratigility's pipe.

So your MYMODULE.services.yml will certainly look like this:

services:
  my_middleware:
    class:      Acme\MyMiddleware
    tags:
      - { name: psr15_middleware }

Using Drupal render arrays in PSR-15 middlewares

This module comes with a service that let's you render Drupal "arrays".

To do so, simply inject the drupal_array_render_caller service in your controller and call the getResponse method.

Below is a sample middleware that returns a "Hello world!" Drupal page when the "/foo" page is hit:

class HelloWorldMiddleware implements MiddlewareInterface
{
    /**
     * @var DrupalArrayRenderCaller
     */
    private $arrayRenderCaller;

    public function __construct(DrupalArrayRenderCaller $arrayRenderCaller)
    {
        $this->arrayRenderCaller = $arrayRenderCaller;
    }

    public function process(ServerRequestInterface $request, RequestHandlerInterface $delegate)
    {
        if (trim($request->getUri()->getPath(), '/') === 'foo') {
            // Let's render a drupal page
            return $this->arrayRenderCaller->getResponse(array(
                '#type' => 'markup',
                '#title' => "My title",
                '#markup' => t('Hello world')
            ));
        } else {
            return $delegate->process($request);
        }
    }
}

How it works

This module listens to the KernelEvents::REQUEST event that is triggered at each request by the Drupal kernel.

The Symfony request is converted into a PSR-7 request and then is sent to Stratigility's middleware pipe.

If a middleware returns a PSR-7 response, this response is sent back to the user. If all middleware are calling the "next" middleware, the final middleware is a dummy middleware that returns a "418 I'm a teapot" response. This response is interpreted by the module as a "I don't care" response, and the rendering is passed to Drupal that will continue its rendering.

Limitations

Stratigility middlewares provided are not "really" middlewares as they cannot modify the request or the response from Drupal. They run "before" Drupal, in a separate middleware stack. This is still very useful if you want to add your own router in front of Drupal!

Currently, the PSR-7 request is never converted back to a Symfony request. This means that any modification done on the PSR-7 request by a middleware will be ignored by Drupal. Due to the way Drupal is built, it is also impossible to catch the Drupal response in a PSR-15 middleware to modify it.

thecodingmachine / drupal-stratigility-bridge

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