Support route-specific middleware pipeline via configuration?

[michaelmoussa]

When defining routes, we can specify the middleware to be executed in the configuration:

return [
    'routes' => [
        [
            'name' => 'foo',
            'path' => '/foo/{id}',
            'middleware' => FooMiddleware::class,
            'allowed_methods' => ['GET'],
        ]
    ]
];

I have a use case where I'd like to service a route by chaining a few different middlewares. They are application-specific middlewares that are shareable among resources (think user input validation, entity retrieval, and things of that nature), but I can only specify a single middleware in this configuration. I considered using the pre_routing and post_routing configuration pipelines, but they execute too early or too late, respectively, and I only need them to execute for this specific route, not for every request.

I managed to implement what I wanted by having my FooMiddleware actually be a middleware pipe:

class FooMiddlewareFactory
{
    public function __invoke(ContainerInterface $container)
    {
        $middleware = new MiddlewarePipe();
        $middleware->pipe($container->get(SomeMiddleware::class));
        $middleware->pipe($container->get(SomeOtherMiddleware::class));
        $middleware->pipe($container->get(YetAnotherMiddleware::class));

        return $middleware;
    }
}

Since a MiddlewarePipe is itself middleware, Expressive will accept it as the target middleware for this route, and execute the middlewares in the proper sequence.

However, it'd be much more convenient to be able to create this pipeline in the configuration rather than needing to create a factory to do it programmatically:

return [
    'routes' => [
        [
            'name' => 'foo',
            'path' => '/foo/{id}',
            'middleware' => [
                SomeMiddleware::class,
                SomeOtherMiddleware::class,
                YetAnotherMiddleware::class,
            ],
            'allowed_methods' => ['GET'],
        ]
    ]
];

This is currently not allowed because the value of middleware must be callable.

1. Is there a better way to do what I'm trying to do already via configuration?
2. Is the inability to create route-specific pipelines like above via configuration an oversight, or intentional?
3. If it's an oversight, would you accept a backwards-compatible patch to get this into 1.0.0?

[weierophinney]

@michaelmoussa Funny — I raised the specter of this in a comment on a previous issue:

• Route with optional params throws errors with Zend Router and View #186 (comment)

I like the idea of the array notation, though we'll have to likely find a way to differentiate between that and a callable. I'll do some thinking on that in the coming days.

[michaelmoussa]

Thanks @weierophinney. I had a couple of ideas in mind already, so since it seems you're open to it, I'll submit something and see if it'll work for you.

[weierophinney]

@michaelmoussa Awesome; thanks!

[danizord]

Could be middleware and middlewares?