Trying to reproduce 1637

app/models/post.js

@@ -0,0 +1,5 @@
+import DS from 'ember-data';
+
+export default DS.Model.extend({
+  user: DS.belongsTo()
+});

app/models/user.js

@@ -1,5 +1,7 @@
 import DS from 'ember-data';
 
 export default DS.Model.extend({
-  name: DS.attr()
+  name: DS.attr(),
+
+  posts: DS.hasMany()
 });

app/routes/application.js

@@ -3,7 +3,7 @@ import Route from '@ember/routing/route';
 export default Route.extend({
 
   model() {
-    return this.store.findRecord('user', 1);
+    return this.store.findRecord('user', 1).catch(console.error);
   }
 
 });

mirage/scenarios/default.js

@@ -1,5 +1,6 @@
 export default function(server) {
 
-  server.create('user', { name: 'Yehuda' });
+  let user = server.create('user', { name: 'Yehuda' });
+  server.createList('post', 3, { user });
 
 }

mirage/serializers/application.js

@@ -1,4 +1,17 @@
 import { JSONAPISerializer } from 'ember-cli-mirage';
 
 export default JSONAPISerializer.extend({
+  alwaysIncludeLinkageData: true,
+
+  keyForAttribute(attr) {
+    return attr.underscore();
+  },
+
+  keyForRelationship(modelName) {
+    return modelName.underscore();
+  },
+
+  keyForModel() { return 'user'; },
+
+  typeKeyForModel(model) { return model.modelName; },
 });