续集 ORM - 错误:不返回数据库值

Question

>我尝试将密码从数据库返回到另一个javascript文件。该函数将正确检索数据。但是当我将值返回给另一个函数时，它将被更改为未定义。我想将密码从model.js返回给controller.js。

法典：型号.js

const Sequelize = require('sequelize'); //import sequelize orm
// connect with psql db
var connection = new Sequelize('emd','postgres','test',{
  dialect : 'postgres'
});
//create a table;
var student = connection.define('student',{
  name : {
    type : Sequelize.STRING,
    allowNull : false},
  email : {
    type: Sequelize.STRING,
    unique : true,
    allowNull : false},
  password : {
    type : Sequelize.STRING,
    allowNull : false },
  mobile : {
    type: Sequelize.BIGINT(11),
    unique : true,
    allowNull : false }
});
var methods = {};
  methods.signup = function(u_name,u_email,u_password,u_mobile){
      connection.sync().then(function(){
        student.create({
          name : u_name,
          email : u_email,
          password : u_email,
          mobile : u_mobile
        });
      });
    }
  methods.login = function(email_id){
    connection.sync().then(function(){
        student.findOne({where : {email : email_id }} ).then(results =>{
          return results.dataValues.password;    
        });
      });
    }
exports.fun = methods;

代码：控制器.js

var model = require('./model.js')
var methods={}
  methods.login = function(email,password){
    let res = model.fun.login(email)
    console.log(res);
    if(password===res){
      console.log("success");
    }
    else {
      console.log("failure");
    }
  }

exports.cont = methods

Answer 1

添加到@Sagar Jojoriya，

像这样更改模型.js

methods.login = function(email_id, callbackFun){
connection.sync().then(function(){
    student.findOne({where : {email : email_id }} ).then(results =>{
      console.log("debug pass => ", results.dataValues.password);
      callbackFun(results.dataValues.password);
    });
  });
}

在您的控制器中.js

methods.login = function(email,password){
    model.fun.login(email, function(resPassword) {
        if(password === resPassword){
        console.log("success");
    } else {
      console.log("failure");
    }
  })
}

Answer 2

这是因为该函数model.fun.login异步的，因此在从该函数获得响应之前，它将移动到返回undefined的下一个语句。

methods.login = function(email,password){
    model.fun.login(email, function(resPassword) {
        if(password === resPassword){
          console.log("success");
        }
        else {
          console.log("failure");
        }
    })
}

Answer 3

您可以返回 Promise 并在 controller 内部then块中处理它。

reutrn student.findOne({where : {email : email_id }} ));

这将返回承诺。在控制器中，可以将该方法调用为

model.fun.login(email).then(function(result){
    console.log(JSON.stringfy(result));
});