Applying hasManyThrough to deeper relationships

Question

The Laravel docs seem to indicate that the hasManyThrough declaration can only be used for relationships that are two levels "deep". What about more complex relationships? For example, a User has many Subjects, each of which has many Decks, each of which has many Cards. It's simple to get all Decks belonging to a User using the hasManyThrough declaration, but what about all Cards belonging to a User?

Answer 1

I created a HasManyThrough relationship with unlimited levels: Repository on GitHub

After the installation, you can use it like this:

class User extends Model {
    use \Staudenmeir\EloquentHasManyDeep\HasRelationships;

    public function cards() {
        return $this->hasManyDeep(Card::class, [Subject::class, Deck::class]);
    }
}

Answer 2

As stated in the comments, hasManyThrough doesn't support this level of specificity. One of the things you can do is return a query builder instance going the opposite direction:

//App\User;

public function cards()
{
    Card::whereHas('decks', function($q){
         return $q->whereHas('subjects', function($q){
            return $q->where('user_id', $this->id);
        });
    });
}

We're going from Cards -> Decks -> Subjects. The subjects should have a user_id column that we can then latch onto.

When called from the user model, it would be done thussly:

$user->cards()->get();