How does react js connect to mongodb?

You will need access to the MongoDB Atlas database for this tutorial. If you don't have an account you can sign up free to follow along.

This tutorial will show you how to build a full-stack MERN application—in this case, an employee database—with the most current tools available. Before you begin, make sure that you are familiar with Node.js and React.js basics and have Node and Create React App installed. You will also need access to the MongoDB Atlas database for this tutorial. The full code is available on this GitHub repo.

What is the MERN Stack?

The MERN stack is a web development framework made up of the stack of MongoDB, Express.js, React.js, and Nodejs. It is one of the several variants of the MEAN stack.

In this MERN stack tutorial, we will utilize these four technologies to develop a basic application that is able to record the information of employees and then display it using a React.

How to Get Started with the MERN Stack

To get started, you will need to do the following:

1. Install Node
   To install Node, go to https://nodejs.org/en/ and download either the LTS version or the current version.

2. Have or Install a Code Editor
   You can use any code editor of your choice for this tutorial. However, for the sake of demonstration, we will be using VS Code editor with the plugin prettier and vscode icons.

Setting Up the Project

(Feel free to code along or to download the full code from this GitHub repo.)

MERN lets us create full-stack solutions. So, to leverage its full potential, we will be creating a MERN stack project. For this project, we will create both a back end and a front end. The front end will be implemented with React and the back end will be implemented with MongoDB, Node, and Express. We will call the front end client and the back end server.

Let’s start by creating an empty directory: mern. This folder will hold all our files after we create a new project. Then we will create a React app—client—in it.

mkdir mern
cd mern
npx create-react-app client

Then, we create a folder for the back end and name it server.

mkdir server

We will jump into the server folder that we created previously and create the server. Then, we will initialize package.json using npm init.

cd server
npm init -y

We will also install the dependencies.

npm install mongodb express cors dotenv

The command above uses a couple of keywords:

• mongodb command installs MongoDB database driver that allows your Node.js applications to connect to the database and work with data.
• express installs the web framework for Node.js. (It will make our life easier.)
• cors installs a Node.js package that allows cross origin resource sharing.
• dotenv installs the module that loads environment variables from a .env file into process.env file. This lets you separate configuration files from the code.

We can check out installed dependencies using the package.json file. It should list the packages along with their versions.

After we have ensured that dependencies were installed successfully, we create a file called server.js with the following code.:

mern/server/server.js

const express = require("express");
const app = express();
const cors = require("cors");
require("dotenv").config({ path: "./config.env" });
const port = process.env.PORT || 5000;
app.use(cors());
app.use(express.json());
app.use(require("./routes/record"));
// get driver connection
const dbo = require("./db/conn");
 
app.listen(port, () => {
  // perform a database connection when server starts
  dbo.connectToServer(function (err) {
    if (err) console.error(err);
 
  });
  console.log(`Server is running on port: ${port}`);
});

Here, we are requiring express and cors to be used. const port process.env.port will access the port variable from the config.env we required.

Connecting to MongoDB Atlas

It’s time to connect our server to the database. We will use MongoDB Atlas as the database. MongoDB Atlas is a cloud-based database service that provides robust data security and reliability. MongoDB Atlas provides a free tier cluster that never expires and lets you access a subset of Atlas features and functionality.

Follow the Get Started with Atlas guide to create an account, deploy your first cluster, and locate your cluster’s connection string.

Now that you have the connection string, go back to the ‘server’ directory and create a ‘config.env’ file. There, assign the connection string to a new ATLAS_URI variable. Once done, your file should look similar to the one below. Replace and the with your database username and password.

mern/server/config.env

ATLAS_URI=mongodb+srv://:@sandbox.jadwj.mongodb.net/employees?retryWrites=true&w=majority
PORT=5000

Create a folder under the server directory—db—and inside it, a file—conn.js. There we can add the following code to connect to our database.

mern/server/db/conn.js

const { MongoClient } = require("mongodb");
const Db = process.env.ATLAS_URI;
const client = new MongoClient(Db, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});
 
var _db;
 
module.exports = {
  connectToServer: function (callback) {
    client.connect(function (err, db) {
      // Verify we got a good "db" object
      if (db)
      {
        _db = db.db("employees");
        console.log("Successfully connected to MongoDB."); 
      }
      return callback(err);
         });
  },
 
  getDb: function () {
    return _db;
  },
};

Server API Endpoints

Database done. Server done. Now it's time for the Server API endpoint. Let's start by creating a routes folder and adding record.js in it. Navigate back to your “server” directory and create the new directory and file:

cd ../server
mkdir routes
touch routes/record.js

The routes/record.js file will also have the following lines of code in it.

mern/server/routes/record.js

const express = require("express");
 
// recordRoutes is an instance of the express router.
// We use it to define our routes.
// The router will be added as a middleware and will take control of requests starting with path /record.
const recordRoutes = express.Router();
 
// This will help us connect to the database
const dbo = require("../db/conn");
 
// This help convert the id from string to ObjectId for the _id.
const ObjectId = require("mongodb").ObjectId;
 
 
// This section will help you get a list of all the records.
recordRoutes.route("/record").get(function (req, res) {
 let db_connect = dbo.getDb("employees");
 db_connect
   .collection("records")
   .find({})
   .toArray(function (err, result) {
     if (err) throw err;
     res.json(result);
   });
});
 
// This section will help you get a single record by id
recordRoutes.route("/record/:id").get(function (req, res) {
 let db_connect = dbo.getDb();
 let myquery = { _id: ObjectId(req.params.id) };
 db_connect
   .collection("records")
   .findOne(myquery, function (err, result) {
     if (err) throw err;
     res.json(result);
   });
});
 
// This section will help you create a new record.
recordRoutes.route("/record/add").post(function (req, response) {
 let db_connect = dbo.getDb();
 let myobj = {
   name: req.body.name,
   position: req.body.position,
   level: req.body.level,
 };
 db_connect.collection("records").insertOne(myobj, function (err, res) {
   if (err) throw err;
   response.json(res);
 });
});
 
// This section will help you update a record by id.
recordRoutes.route("/update/:id").post(function (req, response) {
 let db_connect = dbo.getDb();
 let myquery = { _id: ObjectId(req.params.id) };
 let newvalues = {
   $set: {
     name: req.body.name,
     position: req.body.position,
     level: req.body.level,
   },
 };
 db_connect
   .collection("records")
   .updateOne(myquery, newvalues, function (err, res) {
     if (err) throw err;
     console.log("1 document updated");
     response.json(res);
   });
});
 
// This section will help you delete a record
recordRoutes.route("/:id").delete((req, response) => {
 let db_connect = dbo.getDb();
 let myquery = { _id: ObjectId(req.params.id) };
 db_connect.collection("records").deleteOne(myquery, function (err, obj) {
   if (err) throw err;
   console.log("1 document deleted");
   response.json(obj);
 });
});
 
module.exports = recordRoutes;

If you run the application at this point, you will get the following message in your terminal as the connection establishes.

> node server.js

Server is running on port: 5000
Successfully connected to MongoDB.

That’s it for the back end. Now, we will start working on the front end.

Setting Up the React Application

As we have already set up our React application using the create-react-app command, we can navigate to the client folder and check our React application code.

Let’s flesh out the application, but before we do, we need to install two additional dependencies that will be used in our project. Open a new terminal emulator, navigate to the “client” directory, and install bootstrap and react-router-dom.

npm install bootstrap react-router-dom

bootstrap lets you quickly deploy a template and components for your new web application without having to do everything from scratch. And, the react-router-dom installs React router components for web applications. Make sure your server application is still running!

Setting Up the React Router

Let's start by emptying the src folder and adding two new files in it: index.js and App.js.

rm src/**/*
touch src/index.js src/App.js

Inside src/index.js, we add the following code:

mern/client/src/index.js

import React from "react";
import ReactDOM from "react-dom";
import App from "./App";
import { BrowserRouter } from "react-router-dom";

ReactDOM.render(
  
    
      
    
  ,
  document.getElementById("root")
);

We have used BrowserRouter to keep our UI in sync with the URL. BrowserRouter helps with seamless transitions while switching between components. Basically, it will only reload/refresh the component that needs to be changed instead of refreshing/reloading the entire page. Though BrowserRouter is not a necessity, it is a must if you want your app to be responsive.

Creating Components

After adding the code to index.js files, we will create a components folder inside src. For each component we create, we will add a new .js file inside the components folder. In this case, we will add create.js, edit.js, navbar.js, and recordList.js.

mkdir src/components
(cd src/components &&
touch create.js edit.js navbar.js recordList.js)

A snapshot of each file would look like the following.

create.js

The following code will serve as a creating component for our records. Using this component, users can create a new record. This component will submit a create command to our server.

mern/client/src/components/create.js

import React, { useState } from "react";
import { useNavigate } from "react-router";
 
export default function Create() {
 const [form, setForm] = useState({
   name: "",
   position: "",
   level: "",
 });
 const navigate = useNavigate();
 
 // These methods will update the state properties.
 function updateForm(value) {
   return setForm((prev) => {
     return { ...prev, ...value };
   });
 }
 
 // This function will handle the submission.
 async function onSubmit(e) {
   e.preventDefault();
 
   // When a post request is sent to the create url, we'll add a new record to the database.
   const newPerson = { ...form };
 
   await fetch("http://localhost:5000/record/add", {
     method: "POST",
     headers: {
       "Content-Type": "application/json",
     },
     body: JSON.stringify(newPerson),
   })
   .catch(error => {
     window.alert(error);
     return;
   });
 
   setForm({ name: "", position: "", level: "" });
   navigate("/");
 }
 
 // This following section will display the form that takes the input from the user.
 return (
   

     
Create New Record
     

       

         Name
          updateForm({ name: e.target.value })}
         />
       
       

         Position
          updateForm({ position: e.target.value })}
         />
       
       

         

            updateForm({ level: e.target.value })}
           />
           Intern
         
         

            updateForm({ level: e.target.value })}
           />
           Junior
         
         

            updateForm({ level: e.target.value })}
           />
           Senior
         
       
       

         
       
     
   
 );
}

edit.js

The following code will serve as an editing component for our records. It will use a similar layout to the create component and will eventually submit an update command to our server.

mern/client/src/components/edit.js

import React, { useState, useEffect } from "react";
import { useParams, useNavigate } from "react-router";
 
export default function Edit() {
 const [form, setForm] = useState({
   name: "",
   position: "",
   level: "",
   records: [],
 });
 const params = useParams();
 const navigate = useNavigate();
 
 useEffect(() => {
   async function fetchData() {
     const id = params.id.toString();
     const response = await fetch(`http://localhost:5000/record/${params.id.toString()}`);
 
     if (!response.ok) {
       const message = `An error has occurred: ${response.statusText}`;
       window.alert(message);
       return;
     }
 
     const record = await response.json();
     if (!record) {
       window.alert(`Record with id ${id} not found`);
       navigate("/");
       return;
     }
 
     setForm(record);
   }
 
   fetchData();
 
   return;
 }, [params.id, navigate]);
 
 // These methods will update the state properties.
 function updateForm(value) {
   return setForm((prev) => {
     return { ...prev, ...value };
   });
 }
 
 async function onSubmit(e) {
   e.preventDefault();
   const editedPerson = {
     name: form.name,
     position: form.position,
     level: form.level,
   };
 
   // This will send a post request to update the data in the database.
   await fetch(`http://localhost:5000/update/${params.id}`, {
     method: "POST",
     body: JSON.stringify(editedPerson),
     headers: {
       'Content-Type': 'application/json'
     },
   });
 
   navigate("/");
 }
 
 // This following section will display the form that takes input from the user to update the data.
 return (
   

     
Update Record
     

       

         Name: 
          updateForm({ name: e.target.value })}
         />
       
       

         Position: 
          updateForm({ position: e.target.value })}
         />
       
       

         

            updateForm({ level: e.target.value })}
           />
           Intern
         
         

            updateForm({ level: e.target.value })}
           />
           Junior
         
         

            updateForm({ level: e.target.value })}
           />
           Senior
       
       
       

 
       

         
       
     
   
 );
}

recordList.js

The following code will serve as a viewing component for our records. It will fetch all the records in our database through a GET method.

mern/client/src/components/recordList.js

import React, { useEffect, useState } from "react";
import { Link } from "react-router-dom";
 
const Record = (props) => (