Pass in an id for Authorization Laravel

Question

In my user controller I have an posts function, which gives access to a sub-resource of users. This is accessed through the /users/{id}/posts endpoint.

I want the pass the $id from the request URL into a UserPolicy method:

public function resource($user, $id)
{
    return $user->id === $id;
}

My UserController method:

public function posts(Request $request, $id)
{
    $this->authorize('resource', $id);
    return response()->json(['events' => []], 200);
}

Is there anyway to do this? I notice that Policy methods seem to ignore anything that isn't an object.

Edit:

I am currently using a helper method for this authorization but would like to move it to my Policy to keep all rules together:

public function authorizeResource($id)
{
    if ((int)$id !== (int)$this->auth->user()->id) {
        throw new \Exception;
    }
}

Answer 1

Laravel needs to know which policy class to use. For that you need to specify the model, in this case passing an array with an instance of user first and then the $id. Laravel uses the spread operator and will inject the $id as a parameter on your callback function.

//UserController.php
public function posts(Request $request, $id)
{
    $this->authorize('resource', [User::class, $id]);
    return response()->json(['events' => []], 200);
}