src/Traits/Favoriteable.php
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]