app\models\Beatmapset::favourite PHP Method

    public function favourite($user)
    {
        DB::transaction(function () use($user) {
            try {
                FavouriteBeatmapset::create(['user_id' => $user->user_id, 'beatmapset_id' => $this->beatmapset_id]);
            } catch (QueryException $e) {
                if (is_sql_unique_exception($e)) {
                    return;
                } else {
                    throw $e;
                }
            }
            $this->favourite_count = DB::raw('favourite_count + 1');
            $this->save();
        });
    }