如何链接 MongoDB collections

Question

i am beginner, being fighting with that case already 3 days, please help. Using Node js and Mongoose.

I have users, every user make $ on exact website.

How correctly represent code in Controller to create new User and then retrieve all users + salary?

User Schema:

const mongoose = require('mongoose')
const Schema = mongoose.Schema
const userSchema = new Schema({
    username :{
        type: String,      
    },
    website: {
        sitename: {
            type :String
        },       
        income: [{
            type: Schema.Types.ObjectId,
            ref : 'Income'
        }],
        incomeDate: {
            date: Date,
            default: Date.now
        }
    },
})
module.exports = mongoose.model('User', userSchema)

Income Schema:

const mongoose = require('mongoose')
const Schema = mongoose.Schema
const incomeSchema = new Schema({

 income: {
     type: Number
 },
 user: {
    type: Schema.Types.ObjectId,
    ref : 'User'
 }
})
module.exports = mongoose.model('Income' , incomeSchema)

Controller:

const User = require('../models/user.model')
const Income = require('../models/income.model')

module.exports.createUser= async function(req, res){
    try{
       const newUser = await new User({})

       // How to create user with link to Salary?

       res.status(200).json(newUser )
    }catch{}

}

module.exports.getUsers = async function(req, res){
    try{
       const getAll = await User.find()

       // How to get users with Salary?

       res.status(200).json(getAll )
    }catch{}

}

Routes:

router.post('/new' , controller.createUser)
router.get('/all', controller.getUsers)

Answer 1

Why don't you put income as a field under the user schema but instead create a new collection for it?

Update:

MongoDB populate has always been a confusing feature while the documentation is not doing a very good job explaining it.

So basically when you are creating a new user document, you should store the "id" of the income doc. into the income field. That's essentially what type: Schema.Types.ObjectId means. When you're getting the user document, you should call .populate('website.income') which will then populate the income field. After the population happened, the income document will basically become an embedded document within the user document.

So if you still want to have income in a separate collection, with some changes, your code should be like the following:

    //User Model file
    const mongoose = require('mongoose')
    const Schema = mongoose.Schema
    const userSchema = new Schema({
        username: {
            type: String,
        },
        website: {
            sitename: {
                type: String
            },
            //Remove the array bracket []
            income: {
                type: Schema.Types.ObjectId,
                ref: 'Income'
            },
            incomeDate: {
                date: Date,
                //add missing ()
                default: Date.now()
            }
        },
    });

    //You don't need exports for schemas
    mongoose.model('User', userSchema)

    //Income model file
    const mongoose = require('mongoose')
    const Schema = mongoose.Schema
    const incomeSchema = new Schema({

        income: {
            type: Number
        },

        //No need of ref to the user collection. 
        //Plus if you can't really have two doc referencing one another is this way,
        //there is going to be a problem regarding which one should be created first.
        //Even if the above problem is solved. You will still need to run a update
        //operation to populate the first document created with the id of the 2nd document
    });

    //You don't need exports for schemas
    mongoose.model('Income', incomeSchema)

    //The controller file
    //Dependency
    const mongoose = require('mongoose');

    //Connect to the DB
    const options={
    useNewUrlParser: true,
    useUnifiedTopology: true,
    useFindAndModify: false
    }

    const db = mongoose.createConnection('url', options);
    db
    .once('open', () => dblog.info('DB Connected'))
    .catch(err => dblog.error('Error Connecting to DB' + ' ' + err));


    //Load the models
    require('../models/user.model');
    require('../models/income.model');
    const userBD = db.model('User');
    const incomeDB = db.model('Income');


    //Create new income doc.
    module.exports.createIncome = (req, res) => {

        const income = {
            income: 2000,
        };

        new incomeDB(income)
            .save()
            .then(() => res.json({ msg: 'Income Doc. Updated / Created' }))
            .catch(err => {
                console.log(err);
                res.json({ msg: 'Error Updating  / Creating Income Doc.' });
            })

    };

    //Create new user doc.
    module.exports.createUser = (req, res) => {

        //Query the income db
        incomeDB.find({ income: 2000 })
            .then(income => {

                //Create the user object to be stored
                const newUser = {
                    //Assuming you get the information from a html form of some sort
                    username: req.body.userName,
                    website: {
                        sitename: req.body.siteName,
                        //In order to use .populate() you have to store the id of the income doc here
                        income: income._id,
                    },
                };

                //Save the user object into the user db
                new userBD(newUser)
                    .save()
                    .then(() => res.json({ msg: 'New User Created' }))
                    .catch(err => {
                        console.log(err);
                        res.json({ msg: 'Error Creating New User' });
                    });

            })
            .catch(err => {
                console.log(err);
                res.json({ msg: 'Error Querying Income DB' });
            });

    };


    //Get user doc.
    module.exports.getUser = (req, res) => {

        //Query the user db using user name for example
        userBD.find({ username: 'StackOverflow Admin' })
            //Populate the income field in the website object
            .populate('website.income')
            //Pass the user data into the response
            .then(userData => res.json(userData))
            .catch(err => {
                console.log(err);
                res.json('Error Looking Up DB');
            });
    };