Collection converters support for Future

I want to request that withConverter supports a Future for its fromFirestore argument.

Use case

In some cases, like mine, one entity/data object has another one embedded.

Imagine a collection users and a collection events. Documents in collection events have one reference to a document in users.

In my Flutter app, there is class User and a class Event. Class Event has a member user that holds a User object.

• Class User does have fromFirebase constructor and toFirebase method.
• Class Event has a toFirebase method but cannot have a fromFirebase constructor: instantiating an Event class requires not only retrieving data from events collection, but also awaiting to resolve a document from users collection once I got the document from events and have access to its associated user.

If I could use a Future factory function to construct my Event object, I would be able to use fromFirebase and leverage type safe conversions.

Hope to have explained myself and my use case, and even though I don't think this will be implemented, I just wanted to say that it would be really useful :)