Support setting user from JSON (hydrate) (#730)

* Support setting user from JSON

* flow typing

Author: dplewis

src/CoreManager.js

@@ -122,6 +122,7 @@ type UserController = {
   signUp: (user: ParseUser, attrs: AttributeMap, options: RequestOptions) => Promise;
   logIn: (user: ParseUser, options: RequestOptions) => Promise;
   become: (options: RequestOptions) => Promise;
+  hydrate: (userJSON: AttributeMap) => Promise;
   logOut: () => Promise;
   requestPasswordReset: (email: string, options: RequestOptions) => Promise;
   updateUserOnDisk: (user: ParseUser) => Promise;

src/ParseUser.js

@@ -638,6 +638,21 @@ class ParseUser extends ParseObject {
     return controller.become(becomeOptions);
   }
 
+  /**
+   * Logs in a user with a session token. On success, this saves the session
+   * to disk, so you can retrieve the currently logged in user using
+   * <code>current</code>. If there is no session token the user will not logged in.
+   *
+   * @param {Object} userJSON The JSON map of the User's data
+   * @static
+   * @return {Promise} A promise that is fulfilled with the user when
+   *     the login completes.
+   */
+  static hydrate(userJSON: AttributeMap) {
+    const controller = CoreManager.getUserController();
+    return controller.hydrate(userJSON);
+  }
+
   static logInWith(provider, options) {
     return ParseUser._logInWith(provider, options);
   }
@@ -954,6 +969,17 @@ const DefaultController = {
     });
   },
 
+  hydrate(userJSON: AttributeMap) {
+    const user = new ParseUser();
+    user._finishFetch(userJSON);
+    user._setExisted(true);
+    if (userJSON.sessionToken && canUseCurrentUser) {
+      return DefaultController.setCurrentUser(user);
+    } else {
+      return Promise.resolve(user);
+    }
+  },
+
   logOut(): Promise {
     return DefaultController.currentUserAsync().then((currentUser) => {
       const path = Storage.generatePath(CURRENT_USER_KEY);

src/__tests__/ParseUser-test.js

@@ -287,6 +287,45 @@ describe('ParseUser', () => {
     });
   });
 
+  it('can hydrate a user with sessionToken in server environment', async () => {
+    ParseUser.enableUnsafeCurrentUser();
+    ParseUser._clearCache();
+    const user = await ParseUser.hydrate({
+      objectId: 'uid3',
+      username: 'username',
+      sessionToken: '123abc',
+    });
+    expect(user.id).toBe('uid3');
+    expect(user.isCurrent()).toBe(true);
+    expect(user.existed()).toBe(true);
+  });
+
+  it('can hydrate a user with sessionToken in non server environment', async () => {
+    ParseUser.disableUnsafeCurrentUser();
+    ParseUser._clearCache();
+    const user = await ParseUser.hydrate({
+      objectId: 'uid3',
+      username: 'username',
+      sessionToken: '123abc',
+    });
+    expect(user.id).toBe('uid3');
+    expect(user.isCurrent()).toBe(false);
+    expect(user.existed()).toBe(true);
+  });
+
+  it('can hydrate a user without sessionToken', async () => {
+    ParseUser.enableUnsafeCurrentUser();
+    ParseUser._clearCache();
+    await ParseUser.logOut();
+    const user = await ParseUser.hydrate({
+      objectId: 'uid3',
+      username: 'username',
+    });
+    expect(user.id).toBe('uid3');
+    expect(user.isCurrent()).toBe(false);
+    expect(user.existed()).toBe(true);
+  });
+
   it('can send a password reset request', () => {
     CoreManager.setRESTController({
       request(method, path, body) {