Ember generated ids on subtypes in belongsTo relationship?

I have a ember model in which I have a belongsTo relationship like :slight_smile:

export default DS.Model.extend({
  name: DS.attr('string'),
  entityType: DS.belongsTo('entity-type', { defaultValue() { return {}; }, async: false }), 

The problem is when I GET the model in the route it is assigning an ember generated id to the subtype in belongsTO relationship. { name: "jack" , "entityType" : { "code" : "codeA", "id" : "ember100"} }

Is there a way I can stop it from assigning an id. Is there a primary key concept for subtypes? And how to make sure these generated ids are not serialized on POST?