Serialized hasMany

gistfile1.js

App.ApplicationSerializer = DS.ActiveModelSerializer.extend({

  serializeHasMany: function(record, json, relationship) {
    var key = relationship.key;
    var json_key = key.singularize().decamelize() + '_ids';

    var relationshipType = DS.RelationshipChange.determineRelationshipType(
      record.constructor, relationship);

    if (relationshipType === 'manyToNone' || relationshipType === 'manyToMany' || relationshipType === 'manyToOne') {
      json[json_key] = Ember.get(record, key).mapBy('id');
    }
  }
});