feat(Object): add #revert()

Author: leeyeh

src/object.js

@@ -897,6 +897,20 @@ module.exports = function(AV) {
         return this.set(keysToClear, options);
       },
 
+      /**
+       * Clears any (or specific) changes to the model made since the last save.
+       * @param {string|string[]} [keys] specify keys to revert.
+       */
+      revert(keys) {
+        const lastOp = _.last(this._opSetQueue);
+        const _keys = ensureArray(keys || _.keys(lastOp));
+        _keys.forEach(key => {
+          delete lastOp[key];
+        });
+        this._rebuildAllEstimatedData();
+        return this;
+      },
+
       /**
        * Returns a JSON-encoded set of operations to be sent with the next save
        * request.

storage.d.ts

@@ -303,6 +303,7 @@ export class Object extends BaseObject {
   change(options: any): this;
   changedAttributes(diff: any): boolean;
   clear(options: any): any;
+  revert(keys?: string | string[]): this;
   clone(): this;
   destroy(options?: Object.DestroyOptions): Promise<this>;
   dirty(attr: String): boolean;

test/object.js

@@ -322,6 +322,40 @@ describe('Objects', function() {
     });
   });
 
+  describe('revert', () => {
+    const data = {
+      name: 'AVOSCloud',
+      age: 0,
+      objectId: '11111111111',
+      className: 'Test',
+      __type: 'Object',
+    };
+
+    it('revert all', () => {
+      const object = AV.parseJSON(data);
+      object.set({
+        name: 'LeanCoud',
+        age: 1,
+      });
+      object.revert();
+      object.dirty().should.eql(false);
+      object.get('name').should.eql('AVOSCloud');
+      object.get('age').should.eql(0);
+      object.toFullJSON().should.eql(data);
+    });
+    it('revert keys', () => {
+      const object = AV.parseJSON(data);
+      object.set({
+        name: 'LeanCoud',
+        age: 1,
+      });
+      object.revert('name');
+      object.dirty().should.eql(true);
+      object.get('name').should.eql('AVOSCloud');
+      object.get('age').should.eql(1);
+    });
+  });
+
   describe('query', () => {
     it('should get AV.Query instance', () => {
       const Foo = AV.Object.extend('Foo');