[
    {
        "id": 140,
        "name_first": "hasan",
        "name_last": "hasibul",
        "profile_image": "/assets/images/default-profile-img.png",
        "created_at": "2013-09-18 08:19:50",
        "last_login": "2013-12-26 11:28:44",
        "status": "active",
        "last_update": "2013-10-15 13:40:47",
        "google_refresh_token": null,
        "is_admin": 1,
        "updated_at": null,
        "pivot": {
            "trip_id": 200,
            "user_id": 140
        }
    }

public function trips(){
        return $this->belongsToMany('Trip');
    }

public function users(){
        return $this->belongsToMany('User');
    }

public function index($tripId)
    {
        $userCollection = Trip::find($tripId)->users;
        return $userCollection;
    }

//get all the users belongs to the trip
Route::get('trips/{tripId}/users', array(
    'as' => 'trips/users/index',
    'uses' => 'TripUserController@index'
));

public function toArray()
{
    $attributes = $this->attributesToArray();
    $attributes = array_merge($attributes, $this->relationsToArray());
    unset($attributes['pivot']['user_id']);
    return $attributes;
}

protected $hidden = [
    'pivot'
];