Laravel Route model binding with relationship

问题:

I am wondering if it is possible to return a relationship with laravels Route model binding ?

Say is a have a user model with a relationship 'friends' to other users, and I want to return both the user info and the relationship from a route or controller.

eg for the route domain.tld/user/123

Route::model('user', 'User');

Route::get('/user/{user}', function(User $user) {

    return Response::json($user);

});

this will return me the user info fine but I also want the relationships, is there any easy/proper way to do this ?

I know I can do this

Route::get('/user/{user}', function((User $user) {

    return Response::json(User::find($user['id'])->with('friends')->get());

});

or

Route::get('/user/{id}', function(($id) {

   return Response::json(User::find($id)->with('friends')->get());

});

but I suspect there may be a better way.

回答1:

You can populate the $with property in the User model. Like so;

protected $with = ['friends'];

This will autoload the relationship data for you automatically.

Please Note: This will do it for every user model query.

If you dont want friends to be loaded all the time, then you can bind it to the parameter within your route, like so;

Route::bind('user_id', function($id) {
    return User::with('friends')->findOrFail($id);
});

Route::get('/user/{user_id}', 'BlogController@viewPost');

回答2:

You don’t want to eager-load relationships on every query like Matt Burrow suggests, just to have it available in one context. This is inefficient.

Instead, in your controller action, you can load relationships “on demand” when you need them. So if you use route–model binding to provide a User instance to your controller action, but you also want the friends relationship, you can do this:

class UserController extends Controller
{
    public function show(User $user)
    {
        $user->load('friends');

        return view('user.show', compact('user'));
    }
}

回答3:

Martin Bean's response is probably not the way you want to tackle this, only because it introduces an n+1 to your Controller:

1) It must load the User via Route Model Binding, then....

2) It now loads the relationship for friends

He is correct, however, that you probably don't want to load the relationship every time.

This is why Matt Burrow's solution is probably better (he's binding a different value: instead of {user}, you could use something like {user_with_friends} and bind that separately from {user}...

Personally, I think if you need to load friends for only that route, I'd simply just pass $userId (without binding), and just begin the controller method with:

$user = User::with('friends')->findOrFail($userId);

You can either let Laravel handle the ModelNotFoundException automatically (like it does with Route Model Binding), or wrap it in a try/catch