Is it possible to have a belongsTo relationship which is resolved by another field in the response

Ember Data
1

I receive a response from the server similar to this:

{"entity":"group","entityId":"myId1" }

Now I would reflect that in ember data in a way similar to this, so that entity determines the type of object, that is referenced by the entityId:

export default DS.Model.extend({
  entity: DS.attr({ type: 'string' }),
  entityId: DS.belongsTo(this.entity, { relatedType: this.entity }),
});

However, this does not work as the belongsTo relationship is resolved before the entity has been set and therefor is undefined, leading to ember data expecting a model with name entityId, which obviously does not exist. Is there a way to get this working without too much trouble?