WIP Custom fields feature.

server/src/collection/ResourceFieldMetadataCollection.js

@@ -0,0 +1,14 @@
+import MetableCollection from '@/lib/Metable/MetableCollection';
+import ResourceFieldMetadata from '@/models/ResourceFieldMetadata';
+
+export default class ResourceFieldMetadataCollection extends MetableCollection {
+  /**
+   * Constructor method.
+   */
+  constructor() {
+    super();
+
+    this.setModel(ResourceFieldMetadata);
+    this.extraColumns = ['resource_id', 'resource_item_id'];
+  }
+}