javascript - Bluebird 创建新用户

Question

我是 Bluebird 的新手，我正在尝试创建一个新用户，但 reject 函数没有按预期工作。

问题是它为我创建了用户，即使它启动了错误There nickname is already in use。

下面我粘贴我的代码。

User.js

var User = require('../models/user');
var Promise = require('bluebird');

module.exports = {
  validateFields: function (nickname) {
    return new Promise(function (response, reject) {
      if (!nickname) {
        reject('You must provide the nickname');
      } else if (nickname.length < 4 || nickname.length > 20) {
        reject('The nickname must be longer than 4 and shorter than 20 characters');
      } else {
        nickname = nickname.trim();
        User.findOne({ "nickname": nickname }).exec()
          .then(function (user) {
            if (user) {
              reject('There nickname is already in use');
            } else {
              response();
            }
          }, function (err) {
            reject('There is an error trying to verify the nickname');
          });
      }
    });
  },
  registerUser: function (user_id, nickname) {
    return new User({ user_id: user_id, nickname: nickname }).save();
  }
};

register.js

var validator = require('validator');
var Promise   = require('bluebird');
var Account = require('../../models/account');

module.exports = {
  validateFields: function (email, password) {
    return new Promise(function (response, reject) {
      if (!email) {
        reject('You must provide the email');
      } else if (!password) {
        reject('You must provide the password');
      } else if (email.length < 6) {
        reject('The email is too short');
      } else if (email.length > 40) {
        reject('The email is too long');
      } else if (!validator.isEmail(email)) {
        reject('The email is not valid');
      } else {
        Account.findOne({ email: email }).exec()
          .then(function (account) {
            if (account) {
              reject('There is already an email');
            } else {
              console.log(account);
              response();
            }
          }, function (err) {
            reject('There is an error trying to verify the email');
          });
      }
    });
  },
  registerAccount: function (email, password) {
    return new Account({ email: email, password: password }).save();
  }
};

routes.js

var Promise  = require('bluebird');

var user     = require('./routes/user');
var account  = require('./routes/auth/register');

router.post('/register', function (req, res, next) {
  account.validateFields(req.body.email, req.body.password)
    .then(function () {
      return user.validateFields(req.body.nickname);
    }, function (err) {
      return res.status(400).json({ msg: err });
    })
    .then(function () {
      req.body.email = req.body.email.trim();
      req.body.password = req.body.password.trim();
      console.log('bien');
      return account.registerAccount(req.body.email, req.body.password);
    }, function (err) {
      console.log('mal');
      return res.status(400).json({ msg: 'There was an error trying to save the email' });
    })
    .then(function (data) {
      return user.registerUser(data, req.body.nickname);
    }, function (err) {
      return res.status(400).json({ msg: 'There was an error trying to save the user' });
    })
    .then(function () {
      return res.status(200);
    }, function (err) {
      console.log(err);
      return res.status(400).json({ msg: err });
    })
    .catch(function (err) {
      console.log('catch');
      return res.status(400).json({ msg: err });
    });
});

谢谢你的建议。

更新

只是为了澄清每个从 promise 开始并正在寻找最佳实践的人，我想 this链接很有帮助。

Answer 1

TLDR；如果您不希望在错误发生后调用 promise 链中的后续函数，请不要使用 .catch() 或 .then(success , error) 捕获错误。仅在链的末尾捕获以获得整个异步调用链的结果，而不会在错误后产生不需要的调用。

好吧，让我们想象一个只返回被拒绝的 promise 的函数:

function fakeForbiddenAsyncOperation(){
    return new Promise(function(resolve , reject){
        return reject('This operation is forbidden');
    });
}

然后，像这样的 Promise 链:

fakeForbiddenAsyncOperation().then(
function(){
    console.log('first parameter, success');
},
function(err ){
    console.log('second parameter, failure: ' + err);
})
.then(function(){
    console.log('This log is called, because the previous error was catched in the second then() lambda');
})
.catch(console.log);

将让 console.log 'this log is called...' 运行，因为正在处理错误。输出将是:

second parameter, failure: This operation is forbidden

This log is called, because the previous error was catched in the second then() lambda

你想在你的代码中做什么，如果之前验证中有错误，则阻止创建用户，更像是:

fakeForbiddenAsyncOperation().then(
function(){
    console.log('first parameter, success');
})
.then(function(){
    console.log('This log is called');
} , function(err){
    console.log('There was an err: ' + err);
    console.log('this is called at the end, and the previous "this log is called" log wasn\'t fired because there was an unhandled rejection');
});

哪个输出是:

There was an err: Error: This operation is forbidden

this is called at the end, and the previous "this log is called" log wasnt fired because there was an unhandled rejection

因此“第一个参数，成功”日志将永远不会触发(因此，User.create() 函数或您不想执行的任何其他操作，如果有先前的错误，也不会)。

您可能还需要处理 2 个小问题:

Bluebird documentation建议使用 .catch() 而不是 .then(success, failure):

forbiddenAsyncOperation().then(
function(){
    console.log('first parameter, success');
})
.then(function(){
    console.log('This log is called');
})
.catch(function(){
    console.log('this is called at the end, and the previous "this log is called" log wasn\'t fired because there was an unhandled rejection');
});

将表现得像前面的例子。

此外，is better to reject errors instead of strings :

 reject(new Error('The nickname must be longer than 4 and shorter than 20 characters'));

将打印错误堆栈跟踪，而不仅仅是控制台中的一条消息。