Node JS 如何将值保存到 Mongo DB

Question

I am trying to develop simple web application where 1 user can order tea and admin user can see this order. Could you please help me to fix my problem: I can add tea to DB, but then it disappears and count starts from 0 again. I am trying to do it for only one user in DB first. Thanks a lot for your help!

Here is my: app.js:

var mongoose = require("mongoose");
var passport = require("passport");
var bodyParser = require("body-parser");
var User = require("./models/user");
var LocalStrategy = require("passport-local");
var passportLocalMongoose = require("passport-local-mongoose");

mongoose.connect("mongodb://localhost/hairsalon_db");

var app = express();
app.set('view engine', 'ejs');
app.use(bodyParser.urlencoded({extended: true}));
app.use(bodyParser.json());
app.use(require("express-session")({
    resave: false,
    saveUninitialized: false
}));
app.use(passport.initialize());
app.use(passport.session());
app.use(express.static('scripts'));


passport.use(new LocalStrategy(User.authenticate()));
passport.serializeUser(User.serializeUser());
passport.deserializeUser(User.deserializeUser());

app.post("/tea_added", function(req, res){
    const click = {clickTime: new Date()};
    console.log(click);

    User.find({}, function(err, foundData) {
        database = foundData[0];
        console.log(foundData[0]);
        foundData[0].tea = foundData[0].tea + 1;
        console.log(foundData[0]);
    });
});

...

Here is my UserSchema:

var mongoose = require("mongoose");
var passportLocalMongoose = require("passport-local-mongoose");

var UserSchema = new mongoose.Schema({
    username: String,
    password: String,
    tea: {type: Number, default: 0},
    coffee: {type: Number, default: 0}
});

UserSchema.plugin(passportLocalMongoose);

module.exports = mongoose.model("User", UserSchema);

Here is my html page:

<h1>
     Hello, user
</h1>


<button id="add_tea">Add tea</button>
<button id="add_coffee">Add coffee</button>

<script src="add_products.js"></script>

Here is a add_products.js script:

const button = document.getElementById('add_tea');
button.addEventListener('click', function(e) {
    console.log('tea added');

Output in terminal after clicking 2 times "add tea":

{ clickTime: 2019-12-23T17:58:13.926Z }

   { tea: 0,
      coffee: 0,
      _id: 5df9500dcacf170631a3ce72,
      username: 'test2',
      __v: 0 }

    { tea: 1,
      coffee: 0,
      _id: 5df9500dcacf170631a3ce72,
      username: 'test2',
      __v: 0 } 

click again

{ clickTime: 2019-12-23T17:58:31.675Z }

{ tea: 0,
  coffee: 0,
  _id: 5df9500dcacf170631a3ce72,
  username: 'test2',
  __v: 0 }

{ tea: 1,
  coffee: 0,
  _id: 5df9500dcacf170631a3ce72,
  username: 'test2',
  __v: 0 }

Answer 1

You are just updating the document but not saving it to database. find command fetches document from database, so you need to call .save() after updating it.

Just add the below line

app.post("/tea_added", function(req, res){
const click = {clickTime: new Date()};
console.log(click);

User.find({}, function(err, foundData) {
    database = foundData[0];
    console.log(foundData[0]);
    foundData[0].tea = foundData[0].tea + 1;

    //Add the below mentioned line

    User.save(function (err) {
        if(err) {
            console.error('ERROR!');
        }
    });
});

});

Answer 2

First, create counter document for store last sequence. after it, apply pre save hook for update seq of tea

var mongoose = require("mongoose");
var passportLocalMongoose = require("passport-local-mongoose");

var CounterSchema = new mongoose.Schema({
  slug: {type: String, default: 'tea'},
  seq: {type: Number, default: 0}
});
var Counter = mongoose.model('Counter', CounterSchema);

const UserSchema = new mongoose.Schema({
    username: String,
    password: String,
    tea: {type: Number, default: 0},
    coffee: {type: Number, default: 0}
});

UserSchema.pre('save', function(next) {
  var doc = this;
  Counter.findByIdAndUpdate({_id: 'tea'}, {$inc: { seq: 1} }, function(error, counter)   {
      if(error)
      return next(error);
      doc.tea = counter.seq;
      next();
  });
});

UserSchema.plugin(passportLocalMongoose);

module.exports = mongoose.model("User", UserSchema);

Answer 3

Please check on .findOneAndUpdate() , which helps you to achieve things in one DB call :

var mongoose = require("mongoose");
var passport = require("passport");
var bodyParser = require("body-parser");
var User = require("./models/user");
var LocalStrategy = require("passport-local");
var passportLocalMongoose = require("passport-local-mongoose");

mongoose.connect("mongodb://localhost/hairsalon_db");

var app = express();
app.set('view engine', 'ejs');
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(require("express-session")({
    resave: false,
    saveUninitialized: false
}));
app.use(passport.initialize());
app.use(passport.session());
app.use(express.static('scripts'));


passport.use(new LocalStrategy(User.authenticate()));
passport.serializeUser(User.serializeUser());
passport.deserializeUser(User.deserializeUser());

app.post("/tea_added", function (req, res) {
    const click = { clickTime: new Date() };
    console.log(click);

    /** 1) Let's say you get username of user 
        & order details here i.e; tea :1 && coffee : 2 like 
        Example object : req.body = {
                                        username: 'myName',
                                        coffee: 1,
                                        tea: 2
                                    };
                            (Or)

                         req.body = {
                                        username: 'myName',
                                        tea: 1
                                    };                            
    */
    const userName = req.body.username;
    let inputValues = {};
    inputValues.coffee = (req.body.coffee) ? req.body.coffee : 0
    inputValues.tea = (req.body.tea) ? req.body.tea : 0
    // `new: true` is to return newly updated document from DB. In case if no document matches with passed in username then o/p will be null.
    User.findOneAndUpdate({ "username": userName }, { $inc: inputValues }, { new: true}).lean(true).exec((err, res) => {
        if (err) { /** some logic or throw err */ console.error('DB Error') }
        if (res) { /** Send success response */console.log('order added') }else{/** some logic or throw err */ console.error('unable to update/process order')}
    });
});