public function addFavorite($user_id = null)
	{
		$favorite = new Favorite(['user_id' => ($user_id) ? $user_id : Auth::id()]);
		$this->favorites()->save($favorite);
	}
public function addFavorite($user_id = null)
	{
		$favorite = new Favorite(['user_id' => ($user_id) ? $user_id : Auth::id()]);
		$this->favorites()->save($favorite);
	}
public function addFavorite ( $ user_id = null ) { $ favorite = new Favorite ( [ 'user_id' => ( $ user_id ) ? $ user_id : Auth :: id ( ) ] ) ; $ this -> favorites ( ) -> save ( $ favorite ) ; }
Add this Object to the user favorites

@param  int $user_id  [if  null its added to the auth user]
Add this Object to the user favorites