don't serve null authData values (#2320)

spec/ParseUser.spec.js

@@ -2257,6 +2257,27 @@ describe('Parse.User testing', () => {
     })
   });
 
+  it_exclude_dbs(['postgres'])('should not serve null authData keys', (done) => {
+    let database = new Config(Parse.applicationId).database;
+    database.create('_User', {
+      username: 'user',
+      _hashed_password: '$2a$10$8/wZJyEuiEaobBBqzTG.jeY.XSFJd0rzaN//ososvEI4yLqI.4aie',
+      _auth_data_facebook: null
+    }, {}).then(() => {
+      return new Parse.Query(Parse.User)
+        .equalTo('username', 'user')
+        .first({useMasterKey: true});
+    }).then((user) => {
+      let authData = user.get('authData');
+      expect(user.get('username')).toEqual('user');
+      expect(authData).toBeUndefined();
+      done();
+    }).catch((err) => {
+      fail('this should not fail');
+      done();
+    })
+  });
+
   it_exclude_dbs(['postgres'])('should cleanup null authData keys ParseUser update (regression test for #1198, #2252)', (done) => {
     Parse.Cloud.beforeSave('_User', (req, res) => {
       req.object.set('foo', 'bar');

src/RestQuery.js

@@ -394,6 +394,17 @@ RestQuery.prototype.runFind = function() {
     if (this.className === '_User') {
       for (var result of results) {
         delete result.password;
+
+        if (result.authData) {
+          Object.keys(result.authData).forEach((provider) => {
+            if (result.authData[provider] === null) {
+              delete result.authData[provider];
+            }
+          });
+          if (Object.keys(result.authData).length == 0) {
+            delete result.authData;
+          }
+        }
       }
     }