Edit characteristic

app/serializers/characteristic.js

@@ -0,0 +1,18 @@
+import DS from 'ember-data';
+import Ember from 'ember';
+
+export default DS.RESTSerializer.extend({
+  isNewSerializerAPI: true,
+
+  serializeHasMany: function(snapshot, json, relationship) {
+    var key = relationship.key;
+    var hasMany = snapshot.hasMany(key);
+    key = this.keyForRelationship ? this.keyForRelationship(key, "hasMany", "serialize") : key;
+
+    json[key] = [];
+    hasMany.forEach((item) => {
+      json[key].push(+item.get('id'));
+    });
+  }
+
+});