WIP

app/mixins/cleanup-form.js

@@ -0,0 +1,32 @@
+import Ember from 'ember';
+
+const { Mixin, run: { once } } = Ember;
+
+export default Mixin.create({
+  actions: {
+    willTransition(transition) {
+      if (confirm('Any unsaved changes will be discarded.')) {
+        let model = this.get('controller.model');
+        let hasMany = this.get('controller.hasMany');
+
+        hasMany.forEach((relationship) => {
+          model.get(relationship).forEach((r) => {
+            once(this, () => {
+              if (r.get('isNew')) {
+                r.deleteRecord();
+              } else {
+                r.rollbackAttributes();
+              }
+            }, this);
+          });
+        });
+
+        if (model.get('isNew')) {
+          model.deleteRecord();
+        }
+      } else {
+        return false;
+      }
+    },
+  },
+});