Indirect modification of overloaded property has no effect laravel
Due to how accessing model attributes is implemented in Eloquent, when you access $category->specifics, a magic __get() method is called that returns a copy of that attributes value. Therefore, when you add an element to that copy, you are just changing the copy, not the original attributes value. That's why you're getting an error saying that whatever you're doing, it won't have any effect. If you want to add a new element to $category->specifics array, you need to make sure that the magic __set() is used by accessing the attribute in a setter manner, e.g.: $category->specifics = array_merge($category->specifics, $this->request->get('specifics'));