Laravel 5: Querying a many to many relationship without "pivot" in the result

Question

I have the following tables

• users
  • id
• books
  • id
• favourite_books
  • id
  • user_id (FK)
  • book_id (FK)

I have the following Model:

class User {
    public function favouriteBooks()
    {
        return $this->belongsToMany(Book::class, 'favourite_books');
    }
}

I want to get all the ids that belong to a user.

The way I am doing this currently is like so:

$user->favouriteBooks()->select('book_id')->get();

However this returns data like so;

[
   {
     "book_id": 23,
     "pivot": {
       "user_id": 57,
       "book_id": 23
     }
   },
   {
     "book_id": 41,
     "pivot": {
       "user_id": 57,
       "book_id": 41
     }
   },
   ...
]

I want it to return data like so:

[
   23,
   41,
   ...
]

How can I do that?

Answer 1

I recommend putting pivot in the hidden array like in user.php:

protected $hidden = ['pivot'];

which would remove pivot from all json's returned.

Answer 2

Use the pluck() method:

$user->favouriteBooks()->pluck('book_id');