Single Action Controller

The Action does only these things:

  • It collects input from the HTTP request (if needed).
  • It invokes the Domain with those inputs (if required) and retains the result.
  • It builds an HTTP response (typically with the Domain results).

All other logic, including all forms of input validation, error handling, and so on, are therefore pushed out of the Action and into the Domain (for domain logic concerns), or the response Renderer (for presentation logic concerns).

Request and Response

Here is a brief overview of the typical application process that involves different participants:

  • The Slim router and dispatcher receives an HTTP request and dispatches it to an Action.

  • The Action invokes the Domain, collecting any required inputs to the Domain from the HTTP request.

  • The Action then invokes the Renderer with the data it needs to build an HTTP Response.

  • The Renderer builds an HTTP response using the data fed to it by the Action.

  • The Action returns the HTTP response to the Slim response emitter and sends the HTTP Response.

Request and Response

Example 

<?php

namespace App\Action;

use App\Domain\Example\Service\MyService;
use App\Renderer\JsonRenderer;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;

final class ExampleAction
{
    private MyService $myService;
    
    private JsonRenderer $renderer;
    
    public function __construct(MyService $myService, JsonRenderer $renderer)
    {
        $this->myService = $myService;
        $this->renderer = $renderer;
    }

    public function __invoke(ServerRequestInterface $request, ResponseInterface $response): ResponseInterface
    {
        // 1. collect input from the HTTP request (if needed)
        $data = (array)$request->getParsedBody();
        
        // 2. Invokes the Domain (Application-Service)
        // with those inputs (if required) and retains the result
        $domainResult = $this->myService->doSomething($data);
        
        // 3. Build and return an HTTP response
        return $this->renderer->json($response, $domainResult);
    }
}