Extract another middleware from API routing

framework/core/src/Api/Middleware/ReadJsonParameters.php

@@ -0,0 +1,24 @@
+<?php namespace Flarum\Api\Middleware;
+
+use Psr\Http\Message\ResponseInterface as Response;
+use Psr\Http\Message\ServerRequestInterface as Request;
+use Zend\Stratigility\MiddlewareInterface;
+
+class ReadJsonParameters implements MiddlewareInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function __invoke(Request $request, Response $response, callable $out = null)
+    {
+        if (str_contains($request->getHeaderLine('content-type'), 'application/vnd.api+json')) {
+            $input = json_decode($request->getBody(), true);
+
+            foreach ($input as $name => $value) {
+                $request = $request->withAttribute($name, $value);
+            }
+        }
+
+        return $out ? $out($request, $response) : $response;
+    }
+}

framework/core/src/Api/routes.php

@@ -1,6 +1,6 @@
 <?php
 
-use Flarum\Api\Request as ApiRequest;
+use Flarum\Api\Request;
 use Psr\Http\Message\ServerRequestInterface;
 
 $action = function ($class) {
@@ -8,14 +8,8 @@ $action = function ($class) {
         $action = $this->app->make($class);
         $actor = $this->app->make('Flarum\Support\Actor');
 
-        if (str_contains($httpRequest->getHeaderLine('content-type'), 'application/vnd.api+json')) {
+        $input = array_merge($httpRequest->getAttributes(), $routeParams);
-            $input = json_decode($httpRequest->getBody(), true);
+        $request = new Request($input, $actor, $httpRequest);
-        } else {
-            $input = $httpRequest->getAttributes();
-        }
-        $input = array_merge($input, $routeParams);
-
-        $request = new ApiRequest($input, $actor, $httpRequest);
 
         return $action->handle($request);
     };