Problem description

After some discussion with a developer from our partner Adesso I think it should be easier in Sulu to prefill a Add Form with data a PHP endpoint for new resource endpoint.

Proposed solution

I could think by something like this would be awesome:

sulu_admin:
    resources:
        events:
            routes:
                list: app.events
                detail: app.event
+               prefill: app.event_prefill

class EventController {
    #[Route('/admin/api/events/prefill', name: 'app.event_prefill']
    public function prefillAction(): Response
    {
       return new JSONResponse(['someField' => 'somePrefilledValue']);
    }
}

I think it requires some adjustments to add prefill if !id is defined:

The prefill endpoint can return a JSON which will prefill the form store if the form is in add and not edit mode.