Mongo: Field with multiple types

[madad]

Hello!

In a collection I have 1 field which could be either ObjectId or UUID.
I've wrote class ObjectIdOrUUIDField and specified it as a field type:

public class ObjectIdOrUUIDField implements Serializable {
	private UUID uuid;
	private ObjectId object_id;
	
	public ObjectIdOrUUIDField(UUID uuid) {
		this.uuid = uuid;
	}
	
	public ObjectIdOrUUIDField(ObjectId object_id) {
		this.object_id = object_id;
	}
}

This is allows me load objects from the collections but not save. If I tried to save the field is converted into JSON object either:

{
     "m" : {
		"object_id" : ObjectId("512a4a7403648a7456929424")
     }
}

or

{
     "m" : {
		"uuid" : BinData(3,"xIqiFeEaK499zB6ytJxZQw==")
     }
}

But I need the following:

{
     "m" : ObjectId("512a4a7403648a7456929424")
}

or

{
     "m" : BinData(3,"xIqiFeEaK499zB6ytJxZQw==")
}

How can I do it?

[Oliver Gierke]

Implement one Converter<ObjectIdOrUUIDField, DBObject> and one Converter<DBObject, ObjectIdOrUUIDField> and implement the behavior as you need it. I don't think we're going to add dedicated support in the mapping subsystem here as mapping two properties to a single field is usually an invalid mapping introduced by accident.