如何使用nodejs / express将数据存储在mongodb中？

Question

I have created chat application using socket.io and I am storing array of messages. Each array object has message and date . The chat app is working only on client side ie when I refresh the page all previous chats are gone. How can I store the messages programmatically ? using mongodb, nodejs/express and reactjs on client side ?

Code:

server.js:

const express = require('express');
const mongoose = require('mongoose');
const socket = require('socket.io');

const app = express();

const db = require('./config/keys').mongoURI;

mongoose.connect(db, {useNewUrlParser: true})
  .then(() => console.log('Mongodb connected...'))
  .catch( err => console.log(err));

const port = 5000;

let server = app.listen(5000, function(){
  console.log('server is running on port 5000')
});

let io =  socket(server);

io.on("connection", function(socket){
  console.log("Socket Connection Established with ID :"+ socket.id)

      socket.on('SEND_MESSAGE', data => {
        io.emit('RECEIVE_MESSAGE', data);
      });

})

messageSchema.js:

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

// Create Schema
const MessageSchema = new Schema({
  message: {
    type: String,
    required: true
  },
  date: {
    type: Date,
    default: Date.now
  }
});

module.exports = Message = mongoose.model('Message', MessageSchema);

chat.js:

import React, { Component } from 'react'
import './chat.css'
import io from "socket.io-client";

export default class Chat extends Component {

    constructor(props){
        super(props);

        this.state = {
            message: '',
            date: '',
            messages: []
        };

        const socket = io('localhost:5000');

        this.sendMessage = event => {
            event.preventDefault();

            if(this.state.message !== ''){
                socket.emit('SEND_MESSAGE', {
                    message: this.state.message,
                    date: Date.now()
                });
                this.setState({ message: '', date: '' });
            }
        };

        socket.on('RECEIVE_MESSAGE', data => {
            addMessage(data);
        });

        const addMessage = data => {
            console.log(data);
            this.setState({
              messages: [...this.state.messages, data],
            });
            console.log(this.state.message);
            console.log(this.state.messages);
        };

    }

    render() {
        return (
        <div>
                <div id="status"></div>
                <div id="chat">
                    <div className="card">
                        <div id="messages" className="card-block">
                            {this.state.messages.map((message, index) => {
                                    return (
                                        <div key={index} className="msgBox"><p className="msgText">{message.message}</p></div>
                                    )
                            })}
                        </div>
                    </div>
                    <div className="row">
                        <div className="column">
                            <input id="inputmsg" type="text" placeholder="Enter Message...."
                            value={this.state.message} onChange={ev => this.setState({message: ev.target.value})}/>
                        </div>
                        <div className="column2">
                            <button id="send" className="button" onClick={this.sendMessage}>Send</button>
                        </div>
                    </div>
                </div>
        </div>
        )
    }
}

Screenshot:

What modifications should I make in server.js and chat.js so that the chat messages get stored in mongodb database. Do I need to create API endpoint for storing and retrieving previous chats ? Note: I have setup mongodb in mlab with database name mongochat and collection name = chat .

Answer 1

You can try edit your server.js, and do something like this:

var messageSchema = require("path/to/schema");

.
. 
.

socket.on('SEND_MESSAGE', data => {
   io.emit('RECEIVE_MESSAGE', data);
   var newDate = new Date();
   const message = new messageSchema({
       'message': data,
       'date': newDate
   })
   message.save((err, data) => {
      if(err) //do something
      else // do whatever you want
   })
});

You can also create a middleware to provide you a simple service between the MongoDB and the APP.