Create a simple MERN Stack application


Hi guys! Today I brought you an article which is rich in many technologies.. As soon as you heard the title of the article, what comes to your mind? What is MERN STACK? Sometimes, you may have heard MEAN STACK.. Is there any difference between these two? Ya..definitely! The biggest difference is the front-end implementation of two stacks.
MERN means, MongoDB, ExpressJS, ReactJS and NodeJS.. So in the application I create in this article, Backend will be implemented with ExpressJS and frontend will be created using ReactJS.

Let's start!

Special Note: I will use some of my previous articles to give you more explanations. Please refer the links in relevant sections. Otherwise, this article will be a boring and a long one!


Back-end API Implementation

Steps to follow:
1. Initiate the project
2. Implement Express server
3. Connect to MongoDB
4. Create a Schema for the database
5. Create a Rest Controller
6. Implement CRUD functionalities with routing

So guys, if you are following my blog, I have already created a REST API using ExpressJS and MongoDB. Therefore I won't be repeat the same thing again..You can create a full functioning REST API referring to this link. Go there and start your back-end implementation guys! Hurry up!
https://salitha94.blogspot.com/2018/09/create-rest-api-in-express-and-mongodb.html

Only the scenario will be changed! Here I use a CRUD for users. In my post, it has been done for posts. That's the only difference!
So, create a database called api and a collection called users in MongoDB. If you have no understanding on mongodb, click the below link.
Link : https://salitha94.blogspot.com/2018/05/database-crud-operations-with-mongdb.html
Insert some documents into you database.
However, The back-end files for this project will be available here.

API folder - api
UI folder   - client

api/app.js
api/models/User.js
api/routes/router.js

Have you done guys? You can test the API following the steps in the above article..Test it before using it.
Run the API using node app.js or node index.js according to your project setup!
Now I will show the way to build our front-end.


Front-end Implementation


1. Create React application and install Axios

Let's create a fresh React project using command line. Open a cmd/terminal and type the below command. You can give any name.
create-react-app mern-app

2. Create components

Inside the project, there's a folder called src. Open it and create a folder called components. Place all the components in this folder. This is not compulsory. But as a best practice do this. This is the structure of the project.



3. Install React router and implement routing mechanism

Open a terminal and install React router using this command.
npm install --save react-router-dom
Now open App.js and configure the routes for each component. Then Home will be the root component for our project.

src/App.js

src/components/Home.js

import React, { Component } from 'react'

class Home extends Component {
render() {
return (
<div style={{marginTop: "100px"}}>
<h1> Welcome To MERN STACK application!</h1>
</div>
)
}
}
export default Home;

src/components/Navbar.js

import React, { Component } from 'react';
import { Link } from 'react-router-dom';

class Navbar extends Component {
render() {
return (
<div className="Navbar">
<nav className="navbar navbar-expand-lg navbar-dark bg-dark">
<a className="navbar-brand" href="/">MERN STACK APP</a>
<button className="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span className="navbar-toggler-icon"></span>
</button>

<div className="collapse navbar-collapse" id="navbarSupportedContent">
<ul className="navbar-nav mr-auto">
<li className="nav-item active">
<Link
className="nav-link" to="/">Home
</Link>
</li>
<li className="nav-item">
<Link className="nav-link" to="/users">users
</Link>
</li>
<li className="nav-item">
<Link className="nav-link" to="/add">Add user
</Link>
</li>
</ul>
</div>
</nav>
</div>
)
}
}
export default Navbar;



4. Load data from back-end

We have to install a HTTP client to handle data with back-end. So, Axios is the most used client as I know. I will choose it. Install in using this command.
npm install --save axios

Now we are ready to use axios. If you want more explanations on Axios, kindly refer one of my previous articles.

Now it's time to view all users!

I will open my Users.js component. I have to do a GET call to my express back-end to get all the users to my component.

import React, { Component } from 'react'
import axios from 'axios';
import userImg from '../assets/user.png';
import { Link } from 'react-router-dom';

class Users extends Component {
constructor(props) {
super(props);
this.state = {
users: []
}
}

componentDidMount() {
axios.get('http://localhost:4000/api/users')
.then(res => {
console.log(res);
this.setState({ users: res.data })
});
}

render() {

var data = this.state.users;

return (
<div className="users" style={{marginTop: "50px"}}>
<div className="container">
<div className="row">
{data.length > 0 ?
data.map((user, i) => {
return (
<div className="col-lg-6" key={user._id.toString()}>
<div className="card" style={{ marginBottom: "20px"}}>
<div className="card-header text-left">{user.name}</div>
<div className="card-body text-left">
<div className="row">
<div className="col-lg-3">
<img className="img-thumbnail" style={{marginBottom: "10px"}} src={userImg} alt="user"/><br/>
<Link to={"users/"+user._id}>
<button className="btn btn-outline-dark btn-sm">View User</button>
</Link>
</div>
<div className="col-lg-9">
<ul className="list-group">
<li className="list-group-item"><b>Email </b>: {user.email}</li>
<li className="list-group-item"><b>Job </b>: {user.job}</li>
<li className="list-group-item"><b>Phone </b>: {user.phone}</li>
</ul>
</div>
</div>
</div>
</div>
</div>
)}
) : null}
</div>
</div>
</div>
);
}
}
export default Users;

In axios response, I set the state of users array to res.data..Then we have the object array of users stored in users array. API end point is => http://localhost:4000/api/users
Now run the React project and see the result on our routes.
http://localhost:3000/users
You will see a view like this...


In this way, you can implement the other components also.. User component will be also having GET call to our end point => http://localhost:4000/api/users/id to fetch one user by ID.

import React, { Component } from 'react'
import axios from 'axios';
import userImg from '../assets/user.png';
import { Link } from 'react-router-dom';
import { Redirect } from 'react-router';

class User extends Component {
constructor(props) {
super(props);
this.state = {
user: {},
redirect: false
}
this.deleteUser = this.deleteUser.bind(this);
}

componentDidMount() {
axios.get(`http://localhost:4000/api/users/${this.props.match.params.id}`)
.then(res => {
console.log(res)
this.setState({ user: res.data })
});
}

deleteUser(event) {
event.preventDefault();
console.log(this.state.user._id)
axios.post(`http://localhost:4000/api/users/delete/${this.state.user._id}`)
.then(res => {
console.log(res)
this.setState({ redirect: this.state.redirect === false })
});
}

render() {
return (
<div className="container" style={{marginTop: "50px"}}>
<div className="card text-left">
<div className="card-header">Name : {this.state.user.name}</div>
<div className="card-body">
<div className="row">
<div className="col-lg-3">
<img className="img-thumbnail" style={{marginBottom: "10px"}} src={userImg} alt="user"/><br/>
</div>
<div className="col-lg-9">
<p className="card-text">Email : {this.state.user.email}</p>
<p className="card-text">Phone : {this.state.user.phone}</p>
<p className="card-text">Job : {this.state.user.job}</p>
<p className="card-text">Company : {this.state.user.company}</p>
<p className="card-text">Age : {this.state.user.age}</p>
<p className="card-text">City : {this.state.user.city}</p>
</div>
</div>
<hr/>
<div className="row" style={{marginLeft: "0px"}}>
<Link to={this.state.user._id+"/edit"}>
<button className="btn btn-primary">Edit user</button>
</Link>
<form onSubmit={this.deleteUser}>
<button type="submit" className="btn btn-danger" style={{marginLeft: "10px"}}>Delete</button>
</form>
</div>

{this.state.redirect && (
<Redirect to={'/users'}/>
)}

</div>
</div>
</div>
)
}
}
export default User;


Now it's time to view a user by ID!

We have to perform axios GET request with a parameter for ID. The details of a user will be fetched then from our database. User's view...



You can see a button to delete the user. Here, we have to do a POST request to our REST API. Because we have to submit some kind of form data to the back-end to identify the correct user to be deleted. I have designed a form for delete button and set a function called deleteUser to remove the user. Then I implemented the deleted logic with the help of Axios within the function body.

Now it's time to edit a user!

Here, edit User is a link to navigate to a route => http://localhost:3000/users/id/edit
Then EditUser component will be rendered with a Form filled with the data of the user. Then details can be edited and updated! 
There must be handler methods to control our inputs! They are implemented..See the code. You can identify them easily by their names.
Update button again do a submit action for another form. It takes the updated data and send to back-end API to update user. EditUser component code is given below.

src/components/EditUser.js

import React, { Component } from 'react'
import axios from 'axios';
import { Redirect } from 'react-router';

class EditUser extends Component {
constructor(props) {
super(props);
this.state = {
name: "",
email: "",
phone: "",
job: "",
company: "",
age: "",
city: "",
redirect: false
}
this.handleNameChange = this.handleNameChange.bind(this);
this.handleEmailChange = this.handleEmailChange.bind(this);
this.handlePhoneChange = this.handlePhoneChange.bind(this);
this.handleJobChange = this.handleJobChange.bind(this);
this.handleCompanyChange = this.handleCompanyChange.bind(this);
this.handleAgeChange = this.handleAgeChange.bind(this);
this.handleCityChange = this.handleCityChange.bind(this);
this.updateUser = this.updateUser.bind(this);
}

componentDidMount() {
axios.get(`http://localhost:4000/api/users/${this.props.match.params.id}`)
.then(res => {
this.setState({
name: res.data.name,
email: res.data.email,
phone: res.data.phone,
job: res.data.job,
company: res.data.company,
age: res.data.age,
city: res.data.city
})
console.log(res)
});
}

handleNameChange(e) {
this.setState({name: e.target.value})
}

handleEmailChange(e) {
this.setState({email: e.target.value})
}

handlePhoneChange(e) {
this.setState({phone: e.target.value})
}

handleJobChange(e) {
this.setState({job: e.target.value})
}

handleCompanyChange(e) {
this.setState({company: e.target.value})
}

handleAgeChange(e) {
this.setState({age: e.target.value})
}

handleCityChange(e) {
this.setState({city: e.target.value})
}

updateUser(event) {
event.preventDefault();
const userUpdate = {
name: this.state.name,
email: this.state.email,
phone: this.state.phone,
job: this.state.job,
company: this.state.company,
age: this.state.age,
city: this.state.city
}
console.log(userUpdate)
axios.post(`http://localhost:4000/api/users/update/${this.props.match.params.id}`, userUpdate)
.then(res => {
console.log(res);
this.setState({ redirect: this.state.redirect === false })
})
.catch(err => { console.log(err) });
}

render() {
return (
<div className="container" style={{marginTop: "50px"}}>
<form onSubmit={this.updateUser} method="user">
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Name</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleNameChange} name="name" value={this.state.name}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Email</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleEmailChange} name="email" value={this.state.email}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Phone</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handlePhoneChange} name="phone" value={this.state.phone}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Job</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleJobChange} name="job" value={this.state.job}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Company</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleCompanyChange} name="company" value={this.state.company}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Age</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleAgeChange} name="age" value={this.state.age}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">City</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleCityChange} name="city" value={this.state.city}/>
</div>
</div>
<hr/>
<div style={{marginLeft: "0px"}} className="row">
<button type="submit" className="btn btn-success" style={{marginLeft: "0px"}}>Update user</button>
</div>
</form>
{this.state.redirect && (
<Redirect to={'/users'}/>
)}
</div>
)
}
}
export default EditUser;

For editing users, we have a view like this..



Let's add a new user! 

How to add a new user? We have to do a POST request again guys! We need to send form data and insert into database. As we did in editing users, here also we need handler methods to control state values of input fields. AddUser component can be found below..

src/components/AddUser.js

import React, { Component } from 'react';
import axios from 'axios';
import { Redirect } from 'react-router';

class AddUser extends Component {
constructor(props) {
super(props);
this.state = {
name: "",
email: "",
phone: "",
job: "",
company: "",
age: "",
city: "",
redirect: false
}
this.handleNameChange = this.handleNameChange.bind(this);
this.handleEmailChange = this.handleEmailChange.bind(this);
this.handlePhoneChange = this.handlePhoneChange.bind(this);
this.handleJobChange = this.handleJobChange.bind(this);
this.handleCompanyChange = this.handleCompanyChange.bind(this);
this.handleAgeChange = this.handleAgeChange.bind(this);
this.handleCityChange = this.handleCityChange.bind(this);
this.addUser = this.addUser.bind(this);
}

handleNameChange(e) {
this.setState({name: e.target.value})
}

handleEmailChange(e) {
this.setState({email: e.target.value})
}

handlePhoneChange(e) {
this.setState({phone: e.target.value})
}

handleJobChange(e) {
this.setState({job: e.target.value})
}

handleCompanyChange(e) {
this.setState({company: e.target.value})
}

handleAgeChange(e) {
this.setState({age: e.target.value})
}

handleCityChange(e) {
this.setState({city: e.target.value})
}

addUser(event) {
event.preventDefault();
const userAdd = {
name: this.state.name,
email: this.state.email,
phone: this.state.phone,
job: this.state.job,
company: this.state.company,
age: this.state.age,
city: this.state.city
}
console.log(userAdd)
axios.post('http://localhost:4000/api/users/add', userAdd)
.then(res => {
console.log(res);
this.setState({ redirect: this.state.redirect === false });
})
.catch(err => { console.log(err) });
}

render() {
return (
<div className="container" style={{marginTop: "50px"}}>
<form onSubmit={this.addUser} method="user">
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Name</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleNameChange} name="name" value={this.state.name}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Email</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleEmailChange} name="email" value={this.state.email}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Phone</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handlePhoneChange} name="phone" value={this.state.phone}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Job</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleJobChange} name="job" value={this.state.job}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Company</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleCompanyChange} name="company" value={this.state.company}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">Age</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleAgeChange} name="age" value={this.state.age}/>
</div>
</div>
<div className="form-group row">
<label className="col-sm-2 col-form-label text-left">City</label>
<div className="col-sm-10">
<input type="text" className="form-control" onChange={this.handleCityChange} name="city" value={this.state.city}/>
</div>
</div>
<hr/>
<div style={{marginLeft: "0px"}} className="row">
<button type="submit" className="btn btn-warning" style={{marginLeft: "0px"}}>Add User</button>
</div>
</form>
{this.state.redirect && (
<Redirect to={'/users'}/>
)}
</div>
);
}
}

export default AddUser;

How it will be rendered on browser? Here we go...



Now you can add users also! route => http://localhost:3000/add
This is the end of building components for this project.. So now you can run the complete project!
Go into client folder and type npm start to run front-end on your browser.

Full Source Codehttps://github.com/SalithaUCSC/MERN-Stack-UserBook

I have to wrap up guys now! Since this article cover a wider area, article is long a bit..I tried to write it to give some basic ideas also..For beginners, it will be useful..So, this is the end of another React JS + Express JS article..
I will come up with more React ones in future..

Good Bye!!!


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