Dependency Injection & Controllers
Constructor Injection
The Laravel service container is used to resolve all Laravel controllers. As a result, you are able to type-hint any dependencies your controller may need in its constructor. The declared dependencies will automatically be resolved and injected into the controller instance:
<?php
namespace App\Http\Controllers;
use App\Repositories\UserRepository;
class UserController extends Controller
{
/**
* The user repository instance.
*/
protected $users;
/**
* Create a new controller instance.
*
* @param UserRepository $users
* @return void
*/
public function __construct(UserRepository $users)
{
$this->users = $users;
}
}
You may also type-hint any Laravel contract. If the container can resolve it, you can type-hint it. Depending on your application, injecting your dependencies into your controller may provide better testability.
Method Injection
In addition to constructor injection, you may also type-hint dependencies on your controller's methods. A common use-case for method injection is injecting the Illuminate\Http\Request
instance into your controller methods:
<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
class UserController extends Controller
{
/**
* Store a new user.
*
* @param Request $request
* @return Response
*/
public function store(Request $request)
{
$name = $request->name;
//
}
}
If your controller method is also expecting input from a route parameter, list your route arguments after your other dependencies. For example, if your route is defined like so:
Route::put('user/{id}', 'UserController@update');
You may still type-hint the Illuminate\Http\Request
and access your id
parameter by defining your controller method as follows:
<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
class UserController extends Controller
{
/**
* Update the given user.
*
* @param Request $request
* @param string $id
* @return Response
*/
public function update(Request $request, $id)
{
//
}
}