为什么MongoDB不保存我的属性

Question

我在我的数据库中填充了一些虚拟数据，我试图添加用户。创建了一个用户对象，但没有任何属性保存...最新什么？

app.get('/setup', function (req, res) {

    User.findOne({ name: "Nick" }, function (err, user) {

        if (user == undefined) {

            var nick = new User({
                name: "Nick",
            }).save();

            res.json({ "success": true, "msg": "user created" });
        } else {
            res.json({ "success": true, "msg": "user existed" });
        }
    });
});

调用此返回＆＃34;用户创建＆＃34;。这是输出所有用户的方法：

app.get('/users', function(req, res) {

    User.find({}, function(err, user) {
        res.json(user);
    });
});

这里的输出是

[
  {
    "_id": "565772db5f6f2d1c25e999be",
    "__v": 0
  },
  {
    "_id": "5657734ba859fefc1dca77db",
    "__v": 0
  },
  {
    "_id": "5657738ba859fefc1dca77dc",
    "__v": 0
  },
  {
    "_id": "565774f1cf99a2b81fca1e7f",
    "__v": 0
  },
  {
    "_id": "565775f0cf99a2b81fca1e80",
    "__v": 0
  }
]

我试图添加＆＃34;尼克＆＃34;几次没有...任何输入？ ：d

我的Mongoose模型，与其他模型一起位于自己的Model.js文件中：

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

// set up a mongoose model and pass it using module.exports
module.exports = mongoose.model('User', new Schema({ 
    name: String, 
    password: String, 
}));

Answer 1

鉴于您在用户Schema中有一个名称，您还需要等到save（）查询完成然后发送响应：

function ellipsis(elem){
    var html=elem.html(), //get the html of the respective element
        text=html.split('\n'), //split the html by lines and store it into an array
        output=[], //an array to store the final output
        char, //an element to store each charachter to process 
        totalWidth=0, //an array to store the processed width of the text
        charCount=0; //an array to count how many charachters are allowed to be shown in each line
    $.each(text,function(i,v){ //iterating through the array of lines
        charCount=0; //emptying the processed variables
        totalWidth=0; //emptying the processed variables
        for(x=0;x<v.length;x++){ //iterating through each letter of the text
            char=v.substr(x,1); //getting the current charachter
            $('body').append('<span class="char" style="font-size='+elem.css('font-size')+';">'+char+'</span>'); //putting the current charachter inside a span and giving the span the font size of the element so that we can get the width of the charachter
            totalWidth+=$('.char').width(); //adding the width of the charachter to totalWidth to start comparing the total processed width with the element width
            $('.char').remove(); //removing the added span
            if(totalWidth<=elem.width()){ //checking if the total width of charachters surpassed the width of the element
                charCount++; //if not then allowing another charachter to be shown
            }
            else{
                x=v.length; //if it has surpassed it then exiting the for loop
            }
        }
        if(charCount!=v.length){ //checking if the number of allowed charachters is less than the actual line charachter's length
            charCount-=4; //if it is less, taking 3 charachters off (for three dots) and one more for converting the number into the index of the charachter
            output.push(v.substr(0,charCount)+'...'); //showing the allowed number of charachters and adding three dots to the end and storing it to the output array
        }
        else{
            output.push(v); //if it is not less than the actual text then add the actual text to the output
        }
    });
    $.each(output,function(i,v){ //iterating through the output values
        if(v=='')output.splice(i,1); //removing the empty line breaks

    });
    output=output.join('<br>'); //getting the text together and recreating the line breaks by putting a br tag between them
    elem.html(output); //replacing the new processed value with the old value
}
ellipsis($('.cut-off')); //calling the function on the desired element

Answer 2

请尝试使用此代码：

app.get('/setup', function (req, res) {

    User.findOne({ name: "Nick" }, function (err, user) {

        if (!err && user) {
                res.json({ "success": true, "msg": "user existed" });

        } 
        else {

            var nick = new User({name: "Nick" });
            nick.save(function(err){
               if(!err)
                   res.json({ "success": true, "msg": "user created" });
            })

        }
    });
});

Answer 3

您调用的save（）函数不正确，并且遵循其他语言的模式而不是Node.js。

Node.js的工作方式与Java，PHP，Ruby，ASP.net等其他语言完全不同 Javascript本质上完全是异步的，并且Node.js已经作为事件驱动和非阻塞I / O进行了改进。因此，代码执行不会继续进行，除非它已经从它所在的函数收到响应。

因此，在执行save（）方法之后，它会回复一个回调函数，向node.js发送完成响应，以便它可以触发其他执行。正确的代码将是

var user = new User({name: 'Nick'});
user.save(function(err, savedUser) {
    if(err) return res.send(err);
    return res.json({'message': 'User created!', user: savedUser});
});

正如您所看到的那样，只要save（）方法完成，它就会在回调中响应响应，即err和savedUser而不是返回它们，并且将在save方法之后的每个代码都被写入在回调中。

如果我们将您的代码暂存一段时间并分析问题所在，

var nick = new User({
    name: "Nick",
}).save();

res.json({ "success": true, "msg": "user created" });

当调用save（）方法时，node.js将数据和插入触发器一起发送到mongodb，然后继续执行其余的代码。即使数据尚未保存，该代码也会打印“成功”。 因此，Node.js中的几乎每个方法都有一个回调，因为它是最后一个发送完成指示的参数。

Answer 4

您需要在用户架构中定义 name 键才能保存。

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var userSchema = new Schema({
  name: String
});

var User = mongoose.model('User', userSchema);

Answer 5

这是你的代码，它的工作原理。我仅使用module.exports更改var User，因为要在一个页面中收集代码。

那么，可能还有其他问题吗？

祝你好运......

var express = require('express')
var mongoose = require('mongoose')
var mongoDBUrl = "mongodb://1.0.0.1:27027/tests"

var app = express()

var Schema = mongoose.Schema;
var User = mongoose.model('User', new Schema({ 
    name: String, 
    password: String, 
}));

/* Mongoose Database connection */
mongoose.connect(mongoDBUrl)
var db = mongoose.connection
db.on('error', console.error.bind(console, 'Mongo connection error:'))
db.once('open', function (callback) {
  console.log("MongoDB connection has established")
})

app.get('/setup', function (req, res) {
    User.findOne({ name: "Nick" }, function (err, user) {

        if (user == undefined) {

            var nick = new User({
                name: "Nick",
            }).save();

            res.json({ "success": true, "msg": "user created" });
        } else {
            res.json({ "success": true, "msg": "user existed" });
        }
    });
});

app.get('/users', function(req, res) {
console.log("/user works")

    User.find({}, function(err, user) {
        res.json(user);
    });
});


app.listen(1337, function() {
    console.log('node-app is listening HTTP port 1337')
})

Postman结果;