我怎么能叫从猫鼬内req.flash（）？

我有打电话req.flash猫鼬函数中的一个问题。我试图照亮了一切。在我的代码的一部分它的工作原理，但在其他事实并非如此。

我的代码：

 router.post('/chngpwd', function(req, res, next) {
   var {currentpassword, newpassword, confirmnewpassword} = req.body;
   var uid = req.session.passport.user;
   if (newpassword == confirmnewpassword) {
     User.findById(uid).then(dbres => {
     req.flash('error_msg',"THIS MESSAGE DON'T WORK");  //DONT WORK
     });
   }else {
     req.flash('error_msg',"New passwords don't match"); //WORKS
   }
   res.redirect('/adminpanel/1');
});

要将它重定向到/ adminpanel / 1，而无需等待从findById（异步）函数的响应。这应该工作：

router.post('/chngpwd', function(req, res, next) {
   var {currentpassword, newpassword, confirmnewpassword} = req.body;
   var uid = req.session.passport.user;
   if (newpassword == confirmnewpassword) {
     User.findById(uid).then(dbres => {
         req.flash('error_msg',"THIS MESSAGE DON'T WORK");
         res.redirect('/adminpanel/1');
     });
   }else {
     req.flash('error_msg',"New passwords don't match");
     res.redirect('/adminpanel/1');
   }
});