如何避免承诺链中已经发送的标题？

Question

我正在进行一项“更改密码”功能。我开始学习更多关于承诺的知识，并有以下代码：

router.post('/change-password', verifyToken, csrfProtection, (req, res, next) => {
  if (!req.body.password_current || !req.body.password_new) {
    req.flash('info', 'Please fill in both fields.');
    return res.redirect('/change-password');
  }
  const data = {};
  data.password = req.body.password_new;
  tokenHandler.verifyToken(req.cookies.token)
    .then((decoded) => {
      return User.findOne({ '_id.user_id': decoded.user });
    })
    .then((user) => {
      data.userId = ObjectId(user._id.user_id);
      return bcrypt.compare(req.body.password_current, user.password);
    })
    .then((allowed) => {
      if (!allowed) {
        return res.redirect('/change-password');
      }
      console.log('I am not here');
      return User.findOneAndUpdate({ '_id.user_id': data.userId }, { password: data.password }, { new: true });
    })
    .then(() => {
      return res.redirect('/change-password');
    })
    .catch((err) => {
      return next(err);
    });
});

我喜欢承诺是如何阻止‘回调地狱’的。问题是，我正在接收一个“已发送的标题”错误。我知道这是因为我无法逃脱链子，它保存了所有的结果(除非你抛出一个错误)。为了解决这个问题，我使用了以下方法：

router.post('/change-password', verifyToken, csrfProtection, (req, res, next) => {
  if (!req.body.password_current || !req.body.password_new) {
    req.flash('info', 'Please fill in both fields.');
    return res.redirect('/change-password');
  }
  const data = {};
  data.password = req.body.password_new;
  tokenHandler.verifyToken(req.cookies.token)
    .then((decoded) => {
      User.findOne({ '_id.user_id': decoded.user }).then((user) => {
        data.userId = ObjectId(user._id.user_id);
        bcrypt.compare(req.body.password_current, user.password).then((allowed) => {
          if (!allowed) {
            return res.redirect('/change-password');
          }
          User.findOneAndUpdate({ '_id.user_id': data.userId }, { password: data.password }).then((doc) => {
            console.log(doc);
            return res.redirect('/change-password');
          });
        });
      });
    });
});

问题是:是否有更好的解决方案来修复“已发送的标头”错误。因为我觉得我的解决方案实际上离“回调地狱”结构只有几步之遥。

Answer 1

你可以这样重写它

router.post('/change-password', verifyToken, csrfProtection, (req, res, next) => {
  if (!req.body.password_current || !req.body.password_new) {
    req.flash('info', 'Please fill in both fields.');
    return res.redirect('/change-password');
  }
  const data = {};
  data.password = req.body.password_new;
  tokenHandler.verifyToken(req.cookies.token)
    .then((decoded) => {
      return User.findOne({ '_id.user_id': decoded.user });
    })
    .then((user) => {
      data.userId = ObjectId(user._id.user_id);
      return bcrypt.compare(req.body.password_current, user.password);
    })
    .then((allowed) => {
      if (!allowed) {
        return res.redirect('/change-password');
      }
     else{
        console.log('I am not here');
        return User.findOneAndUpdate({ '_id.user_id': data.userId }, { password: data.password }, { new: true })
          .then(() => {
                return res.redirect('/change-password');
             });
       }      
    })
    .catch((err) => {
      return next(err);
    });
});

您可以从then函数中返回承诺链。

Answer 2

根据您的Node版本的不同，您也可以使用异步/等待来重写它。这通常会使事情更容易推理。

router.post('/change-password', verifyToken, csrfProtection, async (req, res, next) => {
if (!req.body.password_current || !req.body.password_new) {
    req.flash('info', 'Please fill in both fields.');
    return res.redirect('/change-password');
}

try {
    const data = {};
    data.password = req.body.password_new;
    const decoded = await tokenHandler.verifyToken(req.cookies.token);
    const user = await User.findOne({ '_id.user_id': decoded.user });
    data.userId = ObjectId(user._id.user_id);
    const allowed = await bcrypt.compare(req.body.password_current, user.password);
    if (!allowed) {
        return res.redirect('/change-password');
    } else {
        await User.findOneAndUpdate({ '_id.user_id': data.userId }, { password: data.password }, { new: true });
    }
    return res.redirect('/change-password');
} catch (err) {
    return next(err);
}
});

您需要Node.js >= 7来使用异步/等待。