php - Indirect modification of overloaded property has no effect when I try to unset() from a multidimensional array

one text

Currently dealing with a multidimensional array here. I'm trying to search for a value and use that to delete an entire array for a like/unlike system similar to twitter.

$user->favs is a JSON column in my mysql db that handles likes.

Problem is that when I run unset(), it gives me

Indirect modification of overloaded property App\Models\User::$favs has no effect

my code:

            if(!in_array($post->id, array_column($user->favs, 'post_id'))) {
                $post->favs++;
                $user->favs = array_merge($user->favs, $favs);
            } else {
                $post->favs--;
                foreach($user->favs as $key => $value) {
                    if($value['post_id'] == $post->id) {
                        $tmp = $user->favs;
                        unset($tmp[$key]);
                    }
                }
            }
            $user->save();
            $tweet->save();

Edit: Solution to this problem in @lagbox's comment.

Explained in detail here, https://laravel.com/docs/9.x/eloquent-mutators#array-and-json-casting

You have to set $user->keys to $tmp

                    if($value['post_id'] == $post->id) {
                        $tmp = $user->favs;
                        unset($tmp[$key]);
                        $user->favs = $tmp
                    }