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蓝鸟创建新用户

bluebird promise javascript

DevStarlight · 技术社区 · 8 年前

我是新来的 Bluebird 我试图创建一个新用户,但是 reject 函数无法按预期工作。

问题是,它创造了我 user 即使它启动了错误 There nickname is already in use .

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();
  }
};

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

this 链接很有用。

1 回复 | 直到 8 年前

Community CDub 5 年前

太长,读不下去了不要使用.catch()或.then(成功, )如果您不希望在发生错误后调用promise链中的后续函数。仅在链的末端捕获,以获得整个异步调用链的结果,而不会出现错误后不需要的调用。

好的,让我们假设一个函数只返回一个被拒绝的承诺:

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

然后,一个承诺链如:

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);

会让那个控制台。日志“调用此日志…”以运行,因为错误正在处理中。输出将是:

第二个参数,失败:禁止此操作

调用此日志是因为在第二个then()lambda中捕获了上一个错误

您希望在代码中执行的操作更类似于以下操作:如果验证中存在以前的错误,则防止创建用户:

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');
});

出现错误:错误:禁止此操作

这在结束时调用,之前的“此日志被调用”日志未被触发,因为存在未处理的拒绝

还有两个您可能需要处理的小问题:

Bluebird documentation 建议使用.catch()而不是.then(成功,失败):

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');
});

将与前面的示例类似。

而且 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消息。