[BUGFIX] Do not deserialize when a relationship named type exists

packages/ember-data/lib/serializers/rest-serializer.js

@@ -149,7 +149,7 @@ var RESTSerializer = JSONSerializer.extend({
     let modelClass = store.modelFor(modelName);
     let serializer = store.serializerFor(modelName);
 
-    const primaryHasTypeAttribute = get(modelClass, 'attributes').get('type');
+    const primaryHasTypeAttribute = get(modelClass, 'attributes').get('type') || get(modelClass, 'relationshipsByName').get('type');
     /*jshint loopfunc:true*/
     arrayHash.forEach((hash) => {
       let { data, included } = this._normalizePolymorphicRecord(store, hash, prop, modelClass, serializer, primaryHasTypeAttribute);
@@ -162,7 +162,7 @@ var RESTSerializer = JSONSerializer.extend({
     return documentHash;
   },
 
-  _normalizePolymorphicRecord(store, hash, prop, primaryModelClass, primarySerializer, primaryHasTypeAttribute) {
+  _normalizePolymorphicRecord: function(store, hash, prop, primaryModelClass, primarySerializer, primaryHasTypeAttribute) {
     let serializer, modelClass;
     // Support polymorphic records in async relationships
     if (!primaryHasTypeAttribute && hash.type && store._hasModelFor(this.modelNameFromPayloadKey(hash.type))) {

packages/ember-data/tests/integration/serializers/rest-serializer-test.js

@@ -1,4 +1,4 @@
-var HomePlanet, league, SuperVillain, EvilMinion, YellowMinion, DoomsdayDevice, Comment, Basket, env;
+var HomePlanet, league, SuperVillain, EvilMinion, YellowMinion, DoomsdayDevice, Comment, Basket, Container, env;
 var run = Ember.run;
 
 module("integration/serializer/rest - RESTSerializer", {
@@ -33,14 +33,19 @@ module("integration/serializer/rest - RESTSerializer", {
       type: DS.attr('string'),
       size: DS.attr('number')
     });
+    Container = DS.Model.extend({
+      type: DS.belongsTo('basket', { async: true }),
+      volume: DS.attr('string')
+    });
     env = setupStore({
       superVillain:   SuperVillain,
       homePlanet:     HomePlanet,
       evilMinion:     EvilMinion,
       yellowMinion:   YellowMinion,
       doomsdayDevice: DoomsdayDevice,
       comment:        Comment,
-      basket:         Basket
+      basket:         Basket,
+      container:      Container
     });
     env.store.modelFor('super-villain');
     env.store.modelFor('home-planet');
@@ -49,6 +54,7 @@ module("integration/serializer/rest - RESTSerializer", {
     env.store.modelFor('doomsday-device');
     env.store.modelFor('comment');
     env.store.modelFor('basket');
+    env.store.modelFor('container');
   },
 
   teardown: function() {
@@ -619,3 +625,27 @@ test("don't polymorphically deserialize base on the type key in payload when a t
   strictEqual(clashingRecord.get('type'), 'yellowMinion');
   strictEqual(clashingRecord.get('size'), 10);
 });
+
+test("don't polymorphically deserialize based on the type key in payload when a relationship exists named type", function() {
+  env.registry.register('serializer:application', DS.RESTSerializer.extend({
+    isNewSerializerAPI: true
+  }));
+
+  env.adapter.findRecord = () => {
+    return {
+      containers: [{ id: 42, volume: '10 liters', type: 1 }],
+      baskets: [{ id: 1, size: 4 }]
+    };
+  };
+
+  run(function() {
+    env.store.findRecord('container', 42).then((container) => {
+      strictEqual(container.get('volume'), '10 liters');
+      return container.get('type');
+    }).then((basket) => {
+      ok(basket instanceof Basket);
+      equal(basket.get('size'), 4);
+    });
+  });
+
+});