Category Archives: React

react js

DNY client (7 – Users)

February 5, 2020javascript, Node JS, Reactadmin

Create the User file under user folder.

Include it into the router.

Then put it into the menu.

user/Users.js

import React, { Component } from "react";

import { getUserList } from "./apiUser";

import DefaultProfile from '../images/default-profile.png';

import { Link } from 'react-router-dom';

class Users extends Component {

constructor() {

super()

this.state = {

users: []

}

componentDidMount() {

getUserList().then(data => {

if (data.error) {

console.log(data.error)

} else {

this.setState({users:data})

}

})

}

renderUsers = users => (

{users.map((user, i) => (

<img

className="card-img-top"

src={DefaultProfile}

alt={user.name}

style={{width: '100%', height: '15vw', objectFit: 'cover' }}

<p className="card-text">{user.email}</p>

<Link

to={`/user/${user._id}`}

className="btn btn-primary">View Profile

</Link>

</div>

))}

</div>

);

render() {

const { users } = this.state

return (

<h2 className="mt-5 mb-5"> Users </h2>

{this.renderUsers(users)}

</div>

);

}

export default Users;

The result is a list of users.

Props Change on Users

1) Go the users list http://localhost:3000/users
2) Click on View Profile link of any user. You’ll get to the profile page of that user with that user’s data.
3) If you were to click on your own profile link above, the component data wouldn’t change. This is because the URL is part of prop. Since you’ve changed the URL, you’re changing the prop. This change happens at this.props.match.params.userId.

This is the props of the component and when it changes, we need to fetch data for the profile user again. However, in our Profile component, we only do this for when componentDidMount. Thus, we need to implement fetch data in a component hook called componentDidUpdate like so:

class Profile extends Component {

// etc

componentDidMount() {

const userId = this.props.match.params.userId

this.initUserID(userId)

}

// componentWillReceiveProps is required if you want to update the state values with new props values,

// this method will get called whenever any change happens to props values.

// However, "componentWillReceiveProps()" has been deprecated.

// You should use, "componentDidUpdate(prevProps, prevState, snapshot)".

//https://stackoverflow.com/questions/46113044/when-to-use-componentwillreceiveprops-lifecycle-method?r=SearchResults

//https://reactjs.org/docs/react-component.html#componentdidupdate

componentDidUpdate(prevProps) {

// Typical usage (don't forget to compare props):

if (this.props.match.params.userId !== prevProps.match.params.userId) {

console.log('user/Profile.js', 'componentDidUpdate');

const userId = this.props.match.params.userId

this.initUserID(userId)

}

// other code

}

user/Profile.js

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import React, { Component } from 'react';

import { IsAuthenticated } from '../auth';

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

import { getUserInfo } from './apiUser';

import DefaultProfile from '../images/default-profile.png'

class Profile extends Component {

constructor() {

super()

this.state = {

user: "",

redirectToSignin: false

}

initUserID = userId => {

let token = IsAuthenticated().token

console.log('0) get user info')

getUserInfo(userId, token)

.then(data => {

console.log('4) callback for logging and presentation')

if (data.error) {

this.setState({ redirectToSignin: true })

} else { this.setState({ user: data }) }

})

console.log('2) finish him!!!')

}

componentDidMount() {

console.log('user/Profile.js', 'componentDidMount');

const userId = this.props.match.params.userId

this.initUserID(userId)

}

// componentWillReceiveProps is required if you want to update the state values with new props values,

// this method will get called whenever any change happens to props values.

// However, "componentWillReceiveProps()" has been deprecated.

// You should use, "componentDidUpdate(prevProps, prevState, snapshot)".

//https://stackoverflow.com/questions/46113044/when-to-use-componentwillreceiveprops-lifecycle-method?r=SearchResults

//https://reactjs.org/docs/react-component.html#componentdidupdate

componentDidUpdate(prevProps) {

// Typical usage (don't forget to compare props):

if (this.props.match.params.userId !== prevProps.match.params.userId) {

console.log('user/Profile.js', 'componentDidUpdate');

const userId = this.props.match.params.userId

this.initUserID(userId)

}

// when route parameter changes, we need to capture that change

// make another fetch request so that our data can be updated

// current when componet mounts, it fetches that time.

render() {

const { user, redirectToSignin } = this.state

if (redirectToSignin) return <Redirect to="/signin" />

return (

<h2 className="mt-5 mb-5">Profile</h2>

<img

className="card-img-top"

src={DefaultProfile}

alt={user.name}

style={{width: '100%', height: '15vw', objectFit: 'cover' }}

<ul>

<li>{user.email}</li>

<li>{user.created && `Joined on ${new Date(user.created).toDateString()}`}</li>

</ul>

</div>

{/* if the authenticated user is same as getUserInfo's id */}

{IsAuthenticated().user &&

IsAuthenticated().user._id === user._id &&

(<div className="d-line-block mt-5">

<Link className="btn btn-raised btn-success mr-5"

to={`/user/edit/${user._id}`}>

Edit Profile

</Link>

<button className="btn btn-raised btn-danger"

to={`/user/delete/${user._id}`}>

Delete Profile

</button>

</div>)

}

</div>

);

}

export default Profile

DNY client (6 – Profile Page)

February 2, 2020javascript, Node JS, Projects, Reactadmin

src/user/Profile.js

import React, { Component } from 'react';

class Profile extends Component {

constructor() {

super()

this.state = {

}

render() {

return (

<h2 className="mt-5 mb-5">Profile</h2>

</div>

);

}

export default Profile

Notice when we added our Profile page, the path is /user/:userId.
This says whenever we have a URL in that format, we’ll hit the Profile component.

src/MainRouter.js

import React from 'react'

import {Route, Switch} from 'react-router-dom'

import Home from './core/Home'

import Signup from './user/Signup'

import Signin from './user/Signin'

import Profile from './user/Profile'

import Menu from './core/Menu'

const MainRouter = () => (

<div>

</Switch>

</div>

)

export default MainRouter;

Use the user object you get from localStorage. Inside that object, you’ll get the user object. Access the _id of the user and use it for the url parameter when we click on the profile link.

src/core/Menu.js

{`${IsAuthenticated().user.name}'s profile`}

</Link>

</li>

When fetching data from Server

import React, { Component } from 'react';

import { IsAuthenticated} from '../auth';

import { Redirect } from 'react-router-dom';

class Profile extends Component {

constructor() {

super()

this.state = {

user: "",

redirectToSignin: false

}

getUserInfo = async (userId, token) => {

console.log(`1) get user info for user id: ${userId}` )

return await fetch(`http://localhost:8080/user/${userId}`, {

method: "GET",

mode: "cors",

headers: {

Accept : "application/json",

"Content-Type": "application/json",

Authorization: `Bearer ${token}`,

'Access-Control-Allow-Origin':'*'

}

})

.then(response => {

console.log('3) response received')

return response.json()

})

.catch(err => {

this.setState({ redirectToSignin: true })

return err

})

}

componentDidMount() {

const userId = this.props.match.params.userId

let token = IsAuthenticated().token

console.log('0) get user info')

this.getUserInfo(userId, token).then(response => {

console.log('4) callback for logging and presentation')

this.setState({ user: response })

})

console.log('2) finish him!!!')

}

render() {

const { user, redirectToSignin } = this.state

if (redirectToSignin) return <Redirect to="/signin" />

return (

<h2 className="mt-5 mb-5">Profile</h2>

<ul>

<li>{user.email}</li>

<li>{`Joined on ${new Date(user.created).toDateString()}`}</li>

</ul>

</div>

);

}

export default Profile

DNY client (5 – Menu and filtering authenticated content)

February 1, 2020javascript, Node JS, Reactadmin

dny-client-5 source code
src/core/Menu.js

We first look at how we decide whether a link is active or not. We do so by looking at the history’s path name and the current path. If they match, then we’re on that page and we color it orange.

The way how we get history is to import withRouter from ‘react-router-dom’ and then using it as middleware on our Menu component.

import React from 'react'

import { Link, withRouter} from 'react-router-dom'

const isActive = (history, path) => {

if (history.location.pathname === path) return {color: "#ff9900"}

else return {color: "#000000"}

}

The history object is returned to our component as an object. Within this object, we look at property location, and find the pathname of what page we’re on.

// history object

{

"length":7,

"action":"POP",

"location": {

"pathname":"/signin",

"search":"",

"hash":"",

"key":"irdfys"

}

Then we implement signout functionality for when we click on sign out link.
1) We first clear out jwt from the local storage
2) we then make a request to the server for it to signout the current user.

export const signout = (next) => {

console.log('Menu.js - sign out function execute')

if (typeof window !== "undefined") localStorage.removeItem("jwt")

next()

return fetch("http://localhost:8080/signout", {

method: "GET"

}).then(response => {

console.log('signout', response)

return response.json()

}).catch(err => console.log(err))

}

Finally, we implment the filtering of which menu item should be visible depending on whether we’re authenticated or not.

Basically, if our local storage has jwt property, then we’re signed in. We need to get this string, parse it into an JS object, and return it. Else, if this jwt property is empty, then we’re not signed in.

export const isAuthenticated = () => {

if (typeof window == "undefined") { return false }

if (localStorage.getItem("jwt")) {

// gets string from localString's key jwt

// parse this string into a JS object

let obj = JSON.parse(localStorage.getItem("jwt"))

console.log('user obj', obj);

return JSON.parse(localStorage.getItem("jwt"))

} else { return false }

}

We then copy and paste template html into our code. Then use the previous functionality for
1) signing out
2) filtering menu items
3) coloring the active link

// use destructuring to get history property from props

const Menu = ({history}) => (

<div>

{!isAuthenticated() && (

</li>

</li>

</li>

</>)}

{isAuthenticated() && (

</li>

<a className="nav-link"

style={

(isActive(history, "/signout"), {cursor: "pointer" })

}

onClick={() => signout( () => history.push('/') )}

Sign Out

</a>

</li>

<a className="nav-link">{isAuthenticated().user.name}</a>

</li>

</>)}

</ul>

</div>

)

export default withRouter(Menu);

DNY client (4 – Signing in)

January 30, 2020javascript, Node JS, Reactadmin

We first create a sign in page routing in our MainRouter. It routes to component Signin

src/MainRouter.js

import React from 'react'

import {Route, Switch} from 'react-router-dom'

import Home from './core/Home'

import Signup from './user/Signup'

import Signin from './user/Signin'

const MainRouter = () => (

<div>

</Switch>

</div>

)

export default MainRouter;

We then create component Signin. It has email and password for the user to sign in with. The error is required for erroneous situations and the redirect to a specific referer page.

src/user/Signin.js

import React, { Component } from 'react';

import {Redirect} from 'react-router-dom';

export class Signin extends Component {

constructor() {

super()

this.state = {

email: "",

password: "",

error: "",

redirectToReferer: false,

}

handleChange = (name) => (event) => {

this.setState({ error : "" })

this.setState({ [name] : event.target.value })

}

We have an authenticate function that gets the jwt token and stores it into local storage. We store the token value on key ‘jwt’.

But before we do so, we need to make sure the window object exists.
Once the token is set, we set the referer to yes.

authenticate(jwt, next) {

if (typeof window !== 'undefined') {

localStorage.setItem("jwt", JSON.stringify(jwt))

next()

}

Once the user clicks submit, we sign by passing in the email and password. We stringify that data and put it in the body of our POST request to http://localhost:8080/signin.

When successful, we should then get the response with token and some data. We then put this token into the localstorage and set the our redirect to yes so that we redirect to the homepage.

clickSubmit = event => {

event.preventDefault()

const { email, password } = this.state

const user = { email, password }

this.signin(user)

.then(data => {

if (data.error) {

this.setState({ error: data.error })

} else {

// 1) authenticate

this.authenticate(data.token, () => {

// 2) redirect to profile page

this.setState({ redirectToReferer: true})

})

}

})

}

signin = user => {

return fetch('http://localhost:8080/signin', {

method: "POST",

mode: "cors",

headers: {

Accept : "application/json",

"Content-Type": "application/json",

'Access-Control-Allow-Origin':'*'

body: JSON.stringify(user),

})

.then(response => {

return response.json()

})

.catch(err => {

return err

})

}

renderSignInForm = (email, password) => {

return (<form>

<label className="text-muted">Email</label>

<input

onChange={this.handleChange("email")}

type="email"

className="form-control"

value={email}

</div>

<label className="text-muted">Password</label>

<input

onChange={this.handleChange("password")}

type="password "

className="form-control"

value={password}

</div>

<button onClick={this.clickSubmit} className="btn btn-raised btn-primary">submit</button>

</form>);

}

render() {

const { email, password, error, redirectToReferer} = this.state

if (redirectToReferer) {

return <Redirect to="/" />

}

if (email) console.log('email', email)

if (password) console.log('password', password)

if (error) console.log('error', error)

if (redirectToReferer) console.log('redirectToReferer', redirectToReferer)

return (

{error}

</div>

{this.renderSignInForm(email, password)}

</div>

);

}

export default Signin

Before you sign in, clear your localStorage first by opening up Inspect Element, then click on the Application tab. On the left-hand side, you’ll see a clearStorage. Click on it to clear any key/values stores previously.

Now, on the left-hand side, make sure you’re still on the Application tab click on the localhost URL. On your browser navigate to localhost:3000/signin. Then sign in using correct credentials. You’ll see that the key/value will be updated with the token given by the server. This is so that whenever you make future requests, you’ll be using this token with each request. The server will verify it and thus authenticate your requests.

After the successful sign in, you’ll be redirected to the home page.

DNY client (3 – Creating a User)

January 29, 2020javascript, Node JS, Reactadmin

On the client side, make sure we create the event handler for the submit button:

src/user/Signup.js

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import React, { Component } from 'react';

export class Signup extends Component {

constructor() {

super()

this.state = {

name: "",

email: "",

password: "",

error: ""

}

// https://stackoverflow.com/questions/33973648/react-this-is-undefined-inside-a-component-function?r=SearchResults

// 1) we use arrow function, so that 'this' is already bound to the component

// 2) if you were to use this.handleChange, you'll have to bind it to the component in

// constructor like this:

// this.handleChange = this.handleChange.bind(this);

// 3) Or do it on the onClick: onClick={this.handleChange.bind(this)}.

// onChange gives event object.

// by definition of curry function, we first give 'name'. Then it return s a function where:

// event => {...}

// onChange gives event obj

// thus, this function will fun.

handleChange = (name) => (event) => {

this.setState({ [name] : event.target.value })

}

// in our Node API

// auth.js - router.post('/signup', userSignupValidator, signup)

clickSubmit = event => {

event.preventDefault()

const { name, email, password } = this.state

const user = { name, email, password }

console.log(JSON.stringify(user))

fetch('http://localhost:8080/signup', {

method: "POST",

mode: "cors",

headers: {

Accept : "application/json",

"Content-Type": "application/json",

'Access-Control-Allow-Origin':'*'

body: JSON.stringify(user),

})

.then(response => {

return response.json()

})

.catch(err => console.log(err ))

}

// when given a curry function

// test = (first) => (second) => {

// console.log('test result: ', first + ', ' + second);

// }

render() {

const { name, email, password } = this.state

if (name) console.log('name', name)

if (email) console.log('email', email)

if (password) console.log('password', password)

// the curry function takes in one parameter

// it returns function:

// second => {

// console.log('test result: ', first + ', ' + second);

// }

//let result = this.test("haha");

// it doesn't run the function without this second parameter, let's give it a parameter:

// result("hehe");

// now, test will run.

return (

<h2 className="mt-5 mb-5">Signup</h2>

<form>

<input

onChange={this.handleChange("name")}

type="text"

className="form-control"

value={this.state.name} />

</div>

<label className="text-muted">Email</label>

<input

onChange={this.handleChange("email")}

type="email"

className="form-control"

value={this.state.email}

</div>

<label className="text-muted">Password</label>

<input

onChange={this.handleChange("password")}

type="password "

className="form-control"

value={this.state.password}

</div>

<button onClick={this.clickSubmit} className="btn btn-raised btn-primary">submit</button>

</form>

</div>

);

}

export default Signup

On the server side, make sure use cors.

To set up: npm i -S cors

app.js:

// @ /routes/index.js

var cors = require('cors');

var app = require('express')();

// Allow all

app.use(cors());

// GET home page

app.get('/', function(req, res, next) {

res.render('index', { title: 'tol-node-public' });

});

module.exports = router;

Now when you fill in the username, password, email, (like I did in the screenshot) you’ll see that the password is ‘compaq’ and does not have a number. Thus, you’ll get a bad request:

Click on the Network tab to see what this bad request is about. You’ll see the request, which is called signup. Click on signup.

In the response from the server, we see that the text tells us that we need a number in our password:

So change our password so that it has a number. This time, when you submit, you’ll see that the response to our request will be successful. When you analyze the response to our request, you’ll see that the json response will have a success message:

Go into your mLab account and you’ll see that our users have the information we just used to create a user:

Now, if you try to submit the same data for registration, the response from the server will tell you that the email you’re using to register already exists:

DNY client (2- Routing)

January 28, 2020javascript, Reactadmin

download dny-client-2
install react router dom package: npm i react-router-dom

In App.js, we extract BrowserRouter from react-router-dom which is the package we just installed.
BrowserRouter needs Router components to let it know where and how to route. Thus we need to implement MainRouter. MainRouter routes ‘/’ to a component called Home. We need to implement this Home component also.

src/App.js

Implement MainRouter

This is the main routing mechanism. We basically extract Route and Switch from the package we just installed. In our case, we need a simple router to route path ‘/’ to component Home

We create this pure component so that it can be used inside component BrowserRouter in App.js
It routes different paths to different components.

src/MainRouter.js

import React from 'react'

import {Route, Switch} from 'react-router-dom'

import Home from './core/Home'

const MainRouter = () => (

<div>

</Switch>

</div>

)

export default MainRouter;

Implement Home component for viewing

We created a router that routes to a Home component. Let us implement that Home component.

First, we create a core folder in src. Then we put Home component in there, which basically just displays the data. This simple display of data is fitting to use a pure component like so:

src/core/Home.js

const Home = () => (

<p className="lead">Welcome to DNY tours</p>

</div>

)

export default Home;

Hence, this core folder will contain all display of views using pure components.

Adding Sign up Page

Create another folder called user, we’ll put all user-related UI in there. Then create file Signup.js:

src/user/Signup.js

import React, { Component } from 'react';

export class Signup extends Component {

constructor() {

super()

this.state = {

name: "",

email: "",

password: "",

error: ""

}

render() {

return (

<h2 className="mt-5 mb-5">Signup</h2>

<form>

</div>

<label className="text-muted">Email</label>

</div>

<label className="text-muted">Password</label>

</div>

<button className="btn btn-raised btn-primary">submit</button>

</form>

</div>

);

}

export default Signup

update src/MainRouter.js like so:

import React from 'react'

import {Route, Switch} from 'react-router-dom'

import Home from './core/Home'

import Signup from './user/Signup'

const MainRouter = () => (

<div>

</Switch>

</div>

)

export default MainRouter;

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