public function updatePhotoCover(Photo $photo)
    {
        // get the photoable
        //$photoable = input('photoable_type_name')::find(input('photoable_id'));

        // set all the albums to cover = false
        Photo::where('photoable_id', input('photoable_id'))
            ->where('photoable_type', input('photoable_type'))
            ->update(['is_cover' => false]);

        // update this photo to is_cover
        $photo->update(['is_cover' => true]);

        return json_response();
    }