Spring boot + React JS CRUD Example Tutorial - React App Frontend - Part 2

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Welcome to the second part of my full-stack app development series. In part 1, we created the backend Spring boot project with CRUD Rest APIs for Employee Management App.

In this part 2, we will create a React App and consume CRUD Restful APIs developed and exposed by the Spring boot project in Part 1.

YouTube Playlist

I suggest you to watch this series on my YouTube channel to understand more about this full-stack app:

Build React JS Frontend Application

Let's go ahead and create a React application to consume CRUD REST APIs.

I suggest you watch a YouTube video tutorial series to understand more about this full-stack app at ReactJS + Spring Boot CRUD Full Stack Application

As we know, React is a JavaScript-based library that does not have the ability to make HTTP requests; thus, we need to use third-party libraries to achieve this.

There are plenty of libraries available to make HTTP calls into React app. A few of them are listed below.

• Axios
• Fetch
• Superagent
• React-axios
• Use-http
• React-request

We will use the Axios HTTP library to make HTTP Get REST API call in this example tutorial.

Let's start with creating a React App using create-react-app CLI.

1 - Create a React UI with Create React App

The Create React App CLI tool is an officially supported way to create single-page React applications. It offers a modern build setup with no configuration.

To create a new app, you may choose one of the following methods:

Using npx

npx create-react-app react-frontend

Using npm

npm init react-app react-frontend

npm init is available in npm 6+

Using Yarn

yarn create react-app react-frontend

Running any of these commands will create a directory called react-frontend inside the current folder. Inside that directory, it will generate the initial project structure and install the transitive dependencies:

react-frontend
├── README.md
├── node_modules
├── package.json
├── .gitignore
├── public
│   ├── favicon.ico
│   ├── index.html
│   ├── logo192.png
│   ├── logo512.png
│   ├── manifest.json
│   └── robots.txt
└── src
    ├── App.css
    ├── App.js
    ├── App.test.js
    ├── index.css
    ├── index.js
    ├── logo.svg
    └── serviceWorker.js

Let's explore important files and folders of the react project.

For the project to build, these files must exist with exact filenames:

• public/index.html is the page template;
• src/index.js is the JavaScript entry point. 

You can delete or rename the other files Let's quickly explore the project structure.

package.json - The package.json file contains all the required dependencies for our React JS project. Most importantly, you can check the current version of React that you are using. It has all the scripts to start, build, and eject our React app.

public folder - The public folder contains index.html. As react is used to build a single page application, we have this single HTML file to render all our components. Basically, it's an HTML template. It has a div element with id as root and all our components are rendered in this div with index.html as a single page for the complete react app.

src folder- In this folder, we have all the global javascript and CSS files. All the different components that we will be building, sit here.

index.js - This is the top renderer of your react app. 

node_modules - All the packages installed by NPM or Yarn will reside inside the node_modules folder.

App.js - The App.js file contains the definition of our App component which actually gets rendered in the browser and this is the root component.

Understand more about creating React App at ReactJS + Spring Boot CRUD Full Stack App - 6 - Creating React App

Here is the final project structure of our React App:

2 - Adding Bootstrap in React Using NPM

Open a new terminal window, navigate to your project's folder, and run the following command:

$ npm install bootstrap --save

After installing the bootstrap package, you will need to import it in your React app entry file.

Open the src/index.js file and add the following code:

import 'bootstrap/dist/css/bootstrap.min.css';

src/index.js

Here is the complete code for the index.js file:

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
import 'bootstrap/dist/css/bootstrap.min.css';

ReactDOM.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>,
  document.getElementById('root')
);

// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: https://bit.ly/CRA-PWA
serviceWorker.unregister();

Understand more about how to use bootstrap in react at ReactJS + Spring Boot CRUD Full Stack App - 7 - Add Bootstrap 4 in React App

3. EmployeeService - Consume CRUD REST API Call

For our API calls, we will be using Axios. Below is the npm command to install Axios.

npm add axios

EmployeeService.js

Let's create a services folder inside the src folder and create a Javascript file named EmployeeService.js. Inside this file, create EmployeeService class with the following methods to make our HTTP REST call via Axios:

import axios from 'axios';

const EMPLOYEE_API_BASE_URL = "http://localhost:8080/api/v1/employees";

class EmployeeService {

    getEmployees(){
        return axios.get(EMPLOYEE_API_BASE_URL);
    }

    createEmployee(employee){
        return axios.post(EMPLOYEE_API_BASE_URL, employee);
    }

    getEmployeeById(employeeId){
        return axios.get(EMPLOYEE_API_BASE_URL + '/' + employeeId);
    }

    updateEmployee(employee, employeeId){
        return axios.put(EMPLOYEE_API_BASE_URL + '/' + employeeId, employee);
    }

    deleteEmployee(employeeId){
        return axios.delete(EMPLOYEE_API_BASE_URL + '/' + employeeId);
    }
}

export default new EmployeeService()

Make sure that you create an object of EmployeService class export it as:

export default new EmployeeService();

Understand more about EmployeeService at ReactJS + Spring Boot CRUD Full Stack Application

4. package.json

This file contains all the required dependencies for our React JS project. Most importantly, you can check the current version of React that you are using. It has all the scripts to start, build, and eject our React app:

{
  "name": "react-frontend",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^4.2.4",
    "@testing-library/react": "^9.5.0",
    "@testing-library/user-event": "^7.2.1",
    "axios": "^0.19.2",
    "bootstrap": "^4.5.0",
    "react": "^16.13.1",
    "react-dom": "^16.13.1",
    "react-router-dom": "^5.2.0",
    "react-scripts": "3.4.1"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}

5. React List Employee Component

In this section, we will create a new folder called components inside the src folder. Then create a new file called ListUserComponent.jsx. Within this file create a React class component named ListUserComponent with the following content:

import React, { Component } from 'react'
import EmployeeService from '../services/EmployeeService'

class ListEmployeeComponent extends Component {
    constructor(props) {
        super(props)

        this.state = {
                employees: []
        }
        this.addEmployee = this.addEmployee.bind(this);
        this.editEmployee = this.editEmployee.bind(this);
        this.deleteEmployee = this.deleteEmployee.bind(this);
    }

    deleteEmployee(id){
        EmployeeService.deleteEmployee(id).then( res => {
            this.setState({employees: this.state.employees.filter(employee => employee.id !== id)});
        });
    }
    viewEmployee(id){
        this.props.history.push(`/view-employee/${id}`);
    }
    editEmployee(id){
        this.props.history.push(`/add-employee/${id}`);
    }

    componentDidMount(){
        EmployeeService.getEmployees().then((res) => {
            this.setState({ employees: res.data});
        });
    }

    addEmployee(){
        this.props.history.push('/add-employee/_add');
    }

    render() {
        return (
            <div>
                 <h2 className="text-center">Employees List</h2>
                 <div className = "row">
                    <button className="btn btn-primary" onClick={this.addEmployee}> Add Employee</button>
                 </div>
                 <br></br>
                 <div className = "row">
                        <table className = "table table-striped table-bordered">

                            <thead>
                                <tr>
                                    <th> Employee First Name</th>
                                    <th> Employee Last Name</th>
                                    <th> Employee Email Id</th>
                                    <th> Actions</th>
                                </tr>
                            </thead>
                            <tbody>
                                {
                                    this.state.employees.map(
                                        employee => 
                                        <tr key = {employee.id}>
                                             <td> { employee.firstName} </td>   
                                             <td> {employee.lastName}</td>
                                             <td> {employee.emailId}</td>
                                             <td>
                                                 <button onClick={ () => this.editEmployee(employee.id)} className="btn btn-info">Update </button>
                                                 <button style={{marginLeft: "10px"}} onClick={ () => this.deleteEmployee(employee.id)} className="btn btn-danger">Delete </button>
                                                 <button style={{marginLeft: "10px"}} onClick={ () => this.viewEmployee(employee.id)} className="btn btn-info">View </button>
                                             </td>
                                        </tr>
                                    )
                                }
                            </tbody>
                        </table>

                 </div>

            </div>
        )
    }
}

export default ListEmployeeComponent

Let's understand the above code.

The componentDidMount() is executed when the component is mounted for the first time. In the implementation, it actually invokes the service class method to fetch the employees from an API call and populates the state variable employees. When there is a change in the state, React Js reacts and updates the UI:

    componentDidMount(){
        EmployeeService.getEmployees().then((res) => {
            this.setState({ employees: res.data});
        });
    }

We are using the ES6 feature that is map operator to loop over our employees list and create the view:

<tbody>
                                {
                                    this.state.employees.map(
                                        employee => 
                                        <tr key = {employee.id}>
                                             <td> { employee.firstName} </td>   
                                             <td> {employee.lastName}</td>
                                             <td> {employee.emailId}</td>
                                             <td>
                                                 <button onClick={ () => this.editEmployee(employee.id)} className="btn btn-info">Update </button>
                                                 <button style={{marginLeft: "10px"}} onClick={ () => this.deleteEmployee(employee.id)} className="btn btn-danger">Delete </button>
                                                 <button style={{marginLeft: "10px"}} onClick={ () => this.viewEmployee(employee.id)} className="btn btn-info">View </button>
                                             </td>
                                        </tr>
                                    )
                                }
                            </tbody>

The constructor() is invoked before the component is mounted. In the constructor, we have declared our state variables and bind the different methods so that they are accessible from the state inside of the render() method.

    constructor(props) {
        super(props)

        this.state = {
                employees: []
        }
        this.addEmployee = this.addEmployee.bind(this);
        this.editEmployee = this.editEmployee.bind(this);
        this.deleteEmployee = this.deleteEmployee.bind(this);
    }

On the click of the Delete button, we use the filter() method of an array to filter out the deleted employee:

    deleteEmployee(id){
        EmployeeService.deleteEmployee(id).then( res => {
            this.setState({employees: this.state.employees.filter(employee => employee.id !== id)});
        });
    }

With the click of the Update button, we will navigate to the Update Employee page using the following code:

    editEmployee(id){
        this.props.history.push(`/add-employee/${id}`);
    }

With the click of the View button, we will navigate to the View Employee page using the following code:

    viewEmployee(id){
        this.props.history.push(`/view-employee/${id}`);
    }

With the click of the Add Employee button, we will navigate to Add Employee page using the following code:

   addEmployee(){
        this.props.history.push('/add-employee/_add');
    }

Understand more about ListEmployeeComponent at ReactJS + Spring Boot CRUD Full Stack App - 8 - Creating React List Employee Component

6. HeaderComponent and FooterComponent

Let's create a new file named HeaderComponent.js and within this file, create a component named HeaderComponent with the following code:

import React, { Component } from 'react'

class HeaderComponent extends Component {
    constructor(props) {
        super(props)

        this.state = {
                 
        }
    }

    render() {
        return (
            <div>
                <header>
                    <nav className="navbar navbar-expand-md navbar-dark bg-dark">
                    <div><a href="https://javaguides.net" className="navbar-brand">Employee Management App</a></div>
                    </nav>
                </header>
            </div>
        )
    }
}

export default HeaderComponent

Let's create a new file named FooterComponent.js and within this file, create a component named FooterComponent with the following code:

import React, { Component } from 'react'

class FooterComponent extends Component {
    constructor(props) {
        super(props)

        this.state = {
                 
        }
    }

    render() {
        return (
            <div>
                <footer className = "footer">
                    <span className="text-muted">All Rights Reserved 2020 @JavaGuides</span>
                </footer>
            </div>
        )
    }
}

export default FooterComponent

Understand more about creating Header and Footer in React app at ReactJS + Spring Boot CRUD Full Stack App - 10 - Add Header and Footer to React App

7. Configure Routing

To use React Router, you first have to install it using NPM:

npm install react-router-dom

You'll need to import BrowserRouter, Route, and Switch from the react-router-dom package:

import React, { Component } from 'react';
import { BrowserRouter, Route, Switch } from 'react-router-dom';

Let's open the App component and configure routing. We use the Switch element (open and closing tags) these ensure that only one component is rendered at a time.

Replace the App component with the following code:

import React from 'react';
import logo from './logo.svg';
import './App.css';
import {BrowserRouter as Router, Route, Switch} from 'react-router-dom'
import ListEmployeeComponent from './components/ListEmployeeComponent';
import HeaderComponent from './components/HeaderComponent';
import FooterComponent from './components/FooterComponent';
import CreateEmployeeComponent from './components/CreateEmployeeComponent';
import ViewEmployeeComponent from './components/ViewEmployeeComponent';

function App() {
  return (
    <div>
        <Router>
              <HeaderComponent />
                <div className="container">
                    <Switch> 
                          <Route path = "/" exact component = {ListEmployeeComponent}></Route>
                          <Route path = "/employees" component = {ListEmployeeComponent}></Route>
                          <Route path = "/add-employee/:id" component = {CreateEmployeeComponent}></Route>
                          <Route path = "/view-employee/:id" component = {ViewEmployeeComponent}></Route>
                          {/* <Route path = "/update-employee/:id" component = {UpdateEmployeeComponent}></Route> */}
                    </Switch>
                </div>
              <FooterComponent />
        </Router>
    </div>
    
  );
}

export default App;

Understand more above routing configuration at ReactJS + Spring Boot CRUD Full Stack App - 11 - Configure Routing

8. Add and Update Employee Component

In this section, we will implement Add employee and update employee functionality. We will use the same React Component to perform both add and update employee operations.

Let's create a new file called CreateEmployeeComponent.jsx. Within this file create a React class component named CreateEmployeeComponent with the following content:

import React, { Component } from 'react'
import EmployeeService from '../services/EmployeeService';

class CreateEmployeeComponent extends Component {
    constructor(props) {
        super(props)

        this.state = {
            // step 2
            id: this.props.match.params.id,
            firstName: '',
            lastName: '',
            emailId: ''
        }
        this.changeFirstNameHandler = this.changeFirstNameHandler.bind(this);
        this.changeLastNameHandler = this.changeLastNameHandler.bind(this);
        this.saveOrUpdateEmployee = this.saveOrUpdateEmployee.bind(this);
    }

    // step 3
    componentDidMount(){

        // step 4
        if(this.state.id === '_add'){
            return
        }else{
            EmployeeService.getEmployeeById(this.state.id).then( (res) =>{
                let employee = res.data;
                this.setState({firstName: employee.firstName,
                    lastName: employee.lastName,
                    emailId : employee.emailId
                });
            });
        }        
    }
    saveOrUpdateEmployee = (e) => {
        e.preventDefault();
        let employee = {firstName: this.state.firstName, lastName: this.state.lastName, emailId: this.state.emailId};
        console.log('employee => ' + JSON.stringify(employee));

        // step 5
        if(this.state.id === '_add'){
            EmployeeService.createEmployee(employee).then(res =>{
                this.props.history.push('/employees');
            });
        }else{
            EmployeeService.updateEmployee(employee, this.state.id).then( res => {
                this.props.history.push('/employees');
            });
        }
    }
    
    changeFirstNameHandler= (event) => {
        this.setState({firstName: event.target.value});
    }

    changeLastNameHandler= (event) => {
        this.setState({lastName: event.target.value});
    }

    changeEmailHandler= (event) => {
        this.setState({emailId: event.target.value});
    }

    cancel(){
        this.props.history.push('/employees');
    }

    getTitle(){
        if(this.state.id === '_add'){
            return <h3 className="text-center">Add Employee</h3>
        }else{
            return <h3 className="text-center">Update Employee</h3>
        }
    }
    render() {
        return (
            <div>
                <br></br>
                   <div className = "container">
                        <div className = "row">
                            <div className = "card col-md-6 offset-md-3 offset-md-3">
                                {
                                    this.getTitle()
                                }
                                <div className = "card-body">
                                    <form>
                                        <div className = "form-group">
                                            <label> First Name: </label>
                                            <input placeholder="First Name" name="firstName" className="form-control" 
                                                value={this.state.firstName} onChange={this.changeFirstNameHandler}/>
                                        </div>
                                        <div className = "form-group">
                                            <label> Last Name: </label>
                                            <input placeholder="Last Name" name="lastName" className="form-control" 
                                                value={this.state.lastName} onChange={this.changeLastNameHandler}/>
                                        </div>
                                        <div className = "form-group">
                                            <label> Email Id: </label>
                                            <input placeholder="Email Address" name="emailId" className="form-control" 
                                                value={this.state.emailId} onChange={this.changeEmailHandler}/>
                                        </div>

                                        <button className="btn btn-success" onClick={this.saveOrUpdateEmployee}>Save</button>
                                        <button className="btn btn-danger" onClick={this.cancel.bind(this)} style={{marginLeft: "10px"}}>Cancel</button>
                                    </form>
                                </div>
                            </div>
                        </div>

                   </div>
            </div>
        )
    }
}

export default CreateEmployeeComponent

Let's understand the above code.

We retrieve employee id from the route using the following line of code:

this.props.match.params.id

In the constructor, we have declared our state variables and bind the different methods so that they are accessible from the state inside of the render() method.

constructor(props) {
        super(props)

        this.state = {
            // step 2
            id: this.props.match.params.id,
            firstName: '',
            lastName: '',
            emailId: ''
        }
        this.changeFirstNameHandler = this.changeFirstNameHandler.bind(this);
        this.changeLastNameHandler = this.changeLastNameHandler.bind(this);
        this.saveOrUpdateEmployee = this.saveOrUpdateEmployee.bind(this);
    }

The componentDidMount() is executed when the component is mounted for the first time. In componentDidMount() method, if the id is _add then we don't do anything else we retrieve employee by id using EmployeeService.getEmployeeById() method:

    componentDidMount(){

        // step 4
        if(this.state.id === '_add'){
            return
        }else{
            EmployeeService.getEmployeeById(this.state.id).then( (res) =>{
                let employee = res.data;
                this.setState({firstName: employee.firstName,
                    lastName: employee.lastName,
                    emailId : employee.emailId
                });
            });
        }        
    }

In the saveOrUpdateEmployee () method, we check if the id is _add then we call EmployeeService.createEmployee() method which internally makes a REST API call to store employee data into MySQL database. If id is any positive number then we call EmployeeService.updateEmployee() method which internally makes a REST API call to store updated employee data into MySQL database:

saveOrUpdateEmployee = (e) => {
        e.preventDefault();
        let employee = {firstName: this.state.firstName, lastName: this.state.lastName, emailId: this.state.emailId};
        console.log('employee => ' + JSON.stringify(employee));

        // step 5
        if(this.state.id === '_add'){
            EmployeeService.createEmployee(employee).then(res =>{
                this.props.history.push('/employees');
            });
        }else{
            EmployeeService.updateEmployee(employee, this.state.id).then( res => {
                this.props.history.push('/employees');
            });
        }
    }

We are using a getTitle() method to get the title for Add and Employee page based on id:

getTitle(){
        if(this.state.id === '_add'){
            return <h3 className="text-center">Add Employee</h3>
        }else{
            return <h3 className="text-center">Update Employee</h3>
        }
    }

On click on the Cancel button, the cancel() method is called and it will navigate the user to the employees list page:

 cancel(){
        this.props.history.push('/employees');
    }

Understand more about CreateEmployeeConponent at ReactJS + Spring Boot CRUD Full Stack App - 13 - Creating React Add Employee Component.

9. View Employee Component

Let's create a new file called ViewEmployeeComponent.jsx. Within this file create a React class component named ViewEmployeeComponent with the following content:

import React, { Component } from 'react'
import EmployeeService from '../services/EmployeeService'

class ViewEmployeeComponent extends Component {
    constructor(props) {
        super(props)

        this.state = {
            id: this.props.match.params.id,
            employee: {}
        }
    }

    componentDidMount(){
        EmployeeService.getEmployeeById(this.state.id).then( res => {
            this.setState({employee: res.data});
        })
    }

    render() {
        return (
            <div>
                <br></br>
                <div className = "card col-md-6 offset-md-3">
                    <h3 className = "text-center"> View Employee Details</h3>
                    <div className = "card-body">
                        <div className = "row">
                            <label> Employee First Name: </label>
                            <div> { this.state.employee.firstName }</div>
                        </div>
                        <div className = "row">
                            <label> Employee Last Name: </label>
                            <div> { this.state.employee.lastName }</div>
                        </div>
                        <div className = "row">
                            <label> Employee Email ID: </label>
                            <div> { this.state.employee.emailId }</div>
                        </div>
                    </div>

                </div>
            </div>
        )
    }
}

export default ViewEmployeeComponent

Understand more about ViewEmployeeConponent at ReactJS + Spring Boot CRUD Full Stack App - 13 - Creating React Add Employee Component.

10. Run React App

Before running React App, make sure that your Spring boot project is up and running.

Use the below command to start the project:

npm start

Use yarn to start the project:

yarn start

Runs the app in development mode. Open http://localhost:3000 to view it in the browser.

11. Demo of Full-Stack App

The demo of this project in below YouTube video tutorial series:

Source code on GitHub

https://github.com/RameshMF/ReactJS-Spring-Boot-CRUD-Full-Stack-App

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