Possible ACL Middleware Implementation for Laravel 5.1.11+

AclMiddleware.php

<?php
use AppName\Posts\Post;
use Illuminate\Http\Request;

class GenericAclMiddleware
{
	private $entityClasses = [
		'post' => Post::class
	];

	public function handle(Request $request, $next, $permission, $entityParam = null)
	{
		$user = $request->user();
		$instance = $this->getEntityInstance($entityParam);
		if($instance) {
			$valid = $user->can($permission, $instance);
		} else {
			$valid = $user->can($permission);
		}
		if($valid) {
			return $next($request);
		}
		abort(403);
	}

	private function getEntityInstance($entityParam)
	{
		if(!$entityParam) {
			return null;
		}
		$entityId = $this->route($entity);
		if(!$entityId) {
			return null;
		}
		$entityClass =  $this->entityClasses[$entity];
		$model = new $entityClass;
		return $modelInstance->findOrFail($entityId);
	}
}

EntityAclMiddlewareTrait.php

<?php
use Illuminate\Http\Request;

/**
 * @property string $entityParam The route parameter containing the instance of the relevant entity
 * @property string $entityClass The class path of the relevant eloquent model
 */
trait EntityAclMiddlewareTrait
{
	public function handle(Request $request, $next, $permission)
	{
		$user = $request->user();
		$instance = $this->getEntityInstance($request);
		$valid = ($instance) ? $user->can($permission, $instance) : $user->can($permission);
		if($valid) {
			return $next($request);
		}
		abort(403);
	}
	
	protected function getEntityInstance(Request $request)
	{
		$entityId = $request->route($this->entityParam);
		if(!$entityId) {
			return null;
		}
		$class = $this->entityClass;
		$instance = new $class();
		return $instance->findOrFail($entityId);
	}
}

PostEntityMiddleware.php

<?php
use AppName\Posts\Post;

class PostEntityMiddleware
{
	use EntityAclMiddlewareTrait;
	
	property $entityClass = Post::class;
	
	property $entityParam = 'posts';
}

routes.php

<?php
Route::post('posts', [
	'middleware' => 'acl:create-posts',
	'uses'      => 'PostsController@store'
]);
Route::put('posts/{post}', [
	'middleware' => 'acl:update-posts,post',
	'uses'      => 'PostsController@update'
]);