ENH: Collections (update) (#40)

Fixes #36

app/mixins/validation.js

@@ -0,0 +1,30 @@
+import Ember from 'ember';
+
+const { Mixin, get } = Ember;
+const { keys } = Object;
+
+export default Mixin.create({
+  validationSave(changeset, schema, postSave) {
+    return changeset
+      .cast(keys(schema))
+      .validate()
+      .then(() => {
+        if (changeset.get('isValid')) {
+          return changeset.save().then(postSave);
+        }
+      })
+      .catch((error) => {
+        /* eslint-disable no-console */
+        console.log(error);
+        /* eslint-enable no-console */
+        get(this, 'model.errors').forEach(({ attribute, message }) => {
+          changeset.pushErrors(attribute, message);
+        });
+      });
+  },
+
+  validationCancel(changeset, postCancel) {
+      changeset.rollback();
+      return postCancel();
+  },
+});