public function unfavourite($user)
{
if (!$this->hasFavourited($user)) {
return;
}
DB::transaction(function () use($user) {
$this->favourites()->where('user_id', $user->user_id)->delete();
$this->favourite_count = DB::raw('GREATEST(favourite_count - 1, 0)');
$this->save();
});
}