Custom page - Data save

Hello, i create a Settings page in my filament admin panel and i use CuratorPickor to add media. I want to save a json of my media and not just an id. Actually in database i have the id (1) but i want a json like that : ({"media" : 1}). Do you know how i can do that and when i go back on the setting page how my input can render the media again with a json ?

Thanks for you help