Question

模型文件中的功能成功运行。但是要知道在注册期间ID是否重复并对其进行验证，我在函数中做了一个return语句。服务器将根据分配给该功能的x值（在控制器文件中）进行响应。

//Model file
const bodyParser = require('body-parser');
const express = require('express');
const { check, validationResult } = require('express-validator');
const router = require('express').Router();
router.use(express.json());
const urlencoded = bodyParser.urlencoded({ extended: false });
const User = require('../DB/User.js'); //

function create_user(id1, name1, Password1) {
    var user1 = new User({
        id: id1,
        name: name1,
        Password: Password1
    });
    let x;
    user1.save(function(err) {
        if (err) {
            if (err.code == 11000) {
                x = 0;
                console.log('user already exists and x= ' + x);
                return x;
            } else {
                console.log(err);
            }
        } else {
            x = 1;
            console.log('Saved successfully and x =' + x);
            return x;
        }
    })
}
module.exports = create_user;

//Controller file
const bodyParser = require('body-parser');
const express = require('express');
const { check, validationResult } = require('express-validator');
const { x } = require('joi');
const create_user = require('../model/Registration.js');
const router = require('express').Router();
router.use(express.json());
const urlencoded = bodyParser.urlencoded({ extended: false });



router.get('/Registration', function(req, res, next) {
    res.render('Registration', { checker: 0 });
});

router.post('/Registraion/sign_up', function(req, res) {
    let x = create_user(req.body.id, req.body.name, req.body.password);
    console.log('x =' + x);
    if (x == 0) {
        req.body.id.setCustomValidity("This id is already used");
        console.log('this id exsists and x =' + x); //the output here is x= undefined
    } else {
        res.redirect('/Registration');
    }
});

module.exports = router;

Answer 1

由于user1.save是异步的，并且create_user在返回之前不等待它解决，因此它返回null。

您可以使用callback或async await模式解决该问题

尝试一下：

function create_user(id1, name1, Password1, callback) {
    var user1 = new User({
        id: id1,
        name: name1,
        Password: Password1
    });
    let x;
    user1.save(function(err) {
        if (err) {
            if (err.code == 11000) {
                x = 0;
                console.log('user already exists and x= ' + x);
                callback(x);
                return x;
            } else {
                console.log(err);
            }
        } else {
            x = 1;
            callback(x);
            console.log('Saved successfully and x =' + x);
            return x;
        }
    })
}


//Controller file
router.post('/Registraion/sign_up', function(req, res) {
    create_user(req.body.id, req.body.name, req.body.password, function(x) {
      console.log('x =' + x);
      if (x == 0) {
        req.body.id.setCustomValidity("This id is already used");
                console.log('this id exsists and x =' + x); //the output here is x= undefined
            } else {
                res.redirect('/Registration');
            }
        });
});

导出的函数返回未定义的NodeJS

1 个答案: