Contextual custom types/encoding (for DateTime & Firestore Timestamps)

[jimmyff]

Hi, I have a large app using built_value and I'm migrating it to using freezed and json_serializable. The app has data models that are shared between the client and server. When they are serialized to/from Firestore the DateTime objects are converted to Timestamps. With built_value I have two sets of serializers, one results in pure Dart DateTime objects and the other (firestoreSerializers) handles the pesky Timestamps, as these are passed to and from the json methods I have the flexibility to use the necessary serializers based on the context:

// Current solution of passing serializers (not using json_serializable)
FooBar.fromJsonMap(
      Serializers serializers, Map<String, dynamic> data) => 
         serializers.deserializeWith(ChatMessage.serializer, data)!;

 Map<String, dynamic> toJsonMap(Serializers serializers) =>
         Map.of(serializers.serialize(this, //....

Is there a Json Serializable recommended way to give me the flexibility to share the same data models but handle the serialization & deserialization of DateTime's differently according to context requirements? There are situations where both the client and server need to serialize & deserialize objects to/from firestore as well as none-Firestore contexts (sending/receiving the objects with cloud-endpoint, caching etc).

Thanks