Allow partial override of contribution attributes

app/components/add-contribution/component.js

@@ -24,10 +24,7 @@ export default Component.extend({
   init () {
     this._super(...arguments);
     this.set('defaultDate', moment().startOf('hour').toDate());
-
+    this.set('defaultAttr', {
-    // Default attributes used by reset
-    if (isEmpty(this.attributes)) {
-      this.set('attributes', {
       contributorId: null,
       kind: null,
       date: this.defaultDate,
@@ -36,6 +33,16 @@ export default Component.extend({
       url: null,
       details: null
     });
+
+    // Default attributes used by reset
+    if (isEmpty(this.attributes)) {
+      this.set('attributes', this.defaultAttr);
+    } else {
+      Object.keys(this.defaultAttr).forEach(a => {
+        if (typeof this.attributes[a] === 'undefined') {
+          this.attributes[a] = this.defaultAttr[a];
+        }
+      })
     }
 
     this.reset();