Develop Reference

Refactor class to function components in React

I'm having a hard time converting these 3 class components to function components, the class components are working i just am trying to convert them for learning purposes.
the API call: yelp.js
const { default: SearchBar } = require("../components/SearchBar/SearchBar");
const Yelp = {
searchYelp(term, location) {
return fetch(`/api/hello?term=${term}&location=${location}`)
.then((response) => {
// console.log(response)
return response.json()
}).then((jsonResponse) => {
// console.log(jsonResponse)
if (jsonResponse.businesses) {
return jsonResponse.businesses.map((business) => {
return {
id: business.id,
imageSrc: business.image_url,
name: business.name,
address: business.location.address1,
city: business.location.city,
state: business.location.state,
zipCode: business.location.zip_code,
category: business.categories.title,
rating: business.rating,
reviewCount: business.review_count,
}
})
}
})
}
}
export default Yelp
The Home component as a function that renders a SearchBar and BusinessList component: Home.js
import React, { useState } from "react";
import BusinessList from '../../../src/components/BusinessList/BusinessList';
import SearchBar from '../../../src/components/SearchBar/SearchBar';
import Yelp from '../../util/yelp';
const Home = (term, location) => {
const [businesses, setBusinesses] = useState([]);
const searchYelp = Yelp.searchYelp(term, location).then(businesses => {
setBusinesses(businesses)
})
return (
<>
<SearchBar searchYelp={searchYelp} />
<BusinessList business={businesses} />
</>
)
}
export default Home;
The Home component as a class: Home.js
// import React from 'react';
// import BusinessList from '../../../src/components/BusinessList/BusinessList';
// import SearchBar from '../../../src/components/SearchBar/SearchBar';
// import Yelp from '../../util/yelp';
// class Home extends React.Component {
// constructor() {
// super();
// this.state = {
// businesses: [],
// };
// this.searchYelp = this.searchYelp.bind(this);
// }
// searchYelp(term, location, sortBy) {
// Yelp.searchYelp(term, location, sortBy).then((businesses) => {
// this.setState({ businesses: businesses })
// })
// }
// render() {
// return (
// <>
// <SearchBar searchYelp={this.searchYelp} />
// <BusinessList businesses={this.state.businesses} />
// </>
// )
// }
// }
// export default Home;
The BusinessList component as a function that renders a Business component: BusinessList.js
import React, { useState } from "react";
import './BusinessList.css';
import Business from '../Business/Business';
function BusinessList(businesses) {
console.log(businesses)
return (
<div className="BusinessList">
{
businesses.map(business => {
<Business key={business.id} business={business} />
})
}
</div>
)
};
export default BusinessList;
The BusinessList component as a class: BusinessList.js
// import React from 'react';
// import './BusinessList.css';
// import Business from '../Business/Business';
// class BusinessList extends React.Component {
// constructor(props) {
// super(props)
// console.log(props.businesses)
// }
// render() {
// return (
// <div className="BusinessList">
// {
// this.props.businesses.map((business) => {
// return <Business key={business.id} business={business} />
// })
// }
// </div>
// )
// }
// };
// export default BusinessList;
The Business component as a function: Business.js
import React from "react";
import './Business.css';
const Business = (business) => {
return (
<div className="Business">
<div className="image-container">
<img src={business.business.imageSrc} alt={business.imageSrc} />
</div>
<h2>{business.business.name}</h2>
<div className="Business-information">
<div className="Business-address">
<p>{business.business.address}</p>
<p>{business.business.city} {business.state} {business.zipCode}</p>
</div>
<div className="Business-reviews">
<h3>{business.business.category}</h3>
<h3 className="rating">{business.business.rating}</h3>
<p>{business.business.reviewCount} reviews</p>
</div>
</div>
</div>
)
};
export default Business;
The Business component as a class: Business.js
// import React from "react";
// import './Business.css';
// class Business extends React.Component {
// render() {
// const { business } = this.props
// return (
// <div className="Business">
// <div className="image-container">
// <img src={business.imageSrc} alt={business.imageSrc} />
// </div>
// <h2>{business.name}</h2>
// <div className="Business-information">
// <div className="Business-address">
// <p>{business.address}</p>
// <p>{business.city} {business.state} {business.zipCode}</p>
// </div>
// <div className="Business-reviews">
// <h3>{business.category}</h3>
// <h3 className="rating">{business.rating}</h3>
// <p>{business.reviewCount} reviews</p>
// </div>
// </div>
// </div>
// )
// }
// };
// export default Business;
EDIT **
My attempt at SearchBar component as function: SearchBar.js
import React, { useState, useEffect } from "react";
import './SearchBar.css';
const SearchBar = (props) => {
const [term, setTerm] = useState('')
const [location, setLocation] = useState('')
const [sortBy, setSortBy] = useState('best_match')
const sortByOptions = {
'Best Match': 'best_match',
'Highest Rated': 'rating',
'Most Reviewed': 'review_count'
};
const handleSortByChange = () => {
setSortBy(sortBy)
// console.log(sortByOption)
console.log(sortBy)
}
const renderSortByOptions = (sortByOptions) => {
// console.log(Object.keys(sortByOptions))
return Object.keys(sortByOptions).map(sortByOption => {
let sortByOptionValue = sortByOptions[sortByOption]
// console.log(sortByOptionValue)
return <li
className={sortBy === sortByOption ? 'active' : ''}
onClick={handleSortByChange}
key={sortByOptionValue}>
{sortByOption}
</li>;
})
}
const handleTermChange = (event) => {
setTerm(event.target.value)
}
const handleLocationChange = (event) => {
setLocation(event.target.value)
}
const handleSearch = (event) => {
event.preventDefault()
props.searchYelp(term, location)
}
return (
<div className="SearchBar">
{props.searchYelp}
<div className="SearchBar-sort-options">
<ul>
{renderSortByOptions(sortByOptions)}
</ul>
</div>
<div className="SearchBar-fields">
<input
onChange={handleTermChange}
placeholder="Search Businesses"
/>
<input
onChange={handleLocationChange}
placeholder="Where?"
/>
<button className="SearchBar-submit" onClick={handleSearch}>Let's Go</button>
</div>
</div>
)
}
export default SearchBar;
EDIT**
SearchBar component as a class: SearchBar.js
import React from 'react';
import './SearchBar.css';
class SearchBar extends React.Component {
constructor(props) {
super(props);
this.state = {
term: '',
location: '',
sortBy: 'best_match'
}
this.handleTermChange = this.handleTermChange.bind(this)
this.handleLocationChange = this.handleLocationChange.bind(this)
this.handleSearch = this.handleSearch.bind(this)
this.sortByOptions = {
'Best Match': 'best_match',
'Highest Rated': 'rating',
'Most Reviewed': 'review_count'
};
}
getSortByClass(sortByOption) {
// console.log(sortByOption)
if (this.state.sortBy === sortByOption) {
return 'active'
}
return ''
}
handleSortByChange(sortByOption) {
this.setState({
sortBy: sortByOption
})
}
handleTermChange(event) {
this.setState({
term: event.target.value
})
}
handleLocationChange(event) {
this.setState({
location: event.target.value
})
}
handleSearch(event) {
this.props.searchYelp(this.state.term, this.state.location, this.state.sortBy)
event.preventDefault()
}
renderSortByOptions() {
return Object.keys(this.sortByOptions).map(sortByOption => {
let sortByOptionValue = this.sortByOptions[sortByOption]
console.log(sortByOptionValue)
return <li
onClick={this.handleSortByChange.bind(this, sortByOptionValue)}
className={this.getSortByClass(sortByOptionValue)}
key={sortByOptionValue}>
{sortByOption}
</li>;
})
}
render() {
return (
<div className="SearchBar">
{this.searchYelp}
<div className="SearchBar-sort-options">
<ul>
{this.renderSortByOptions()}
</ul>
</div>
<div className="SearchBar-fields">
<input onChange={this.handleTermChange} placeholder="Search Businesses" />
<input onChange={this.handleLocationChange} placeholder="Where?" />
<button className="SearchBar-submit" onClick={this.handleSearch}>Let's Go</button>
</div>
</div>
)
}
};
export default SearchBar;
I keep getting the error "Cannot read properties of undefined (reading 'map')
Or the error "Businesses.map is not a function"
Im also a little confused as to why when everything is converted to function components in my final Business component in order to get things to showup im required to pass things in as business.business.imageSrc instead of just business.imageSrc

First in Home searchYelp should be declared as a function so it can be passed as a callback to the SearchBar component.
const Home = () => {
const [businesses, setBusinesses] = useState([]);
const searchYelp = (term, location) => {
Yelp.searchYelp(term, location)
.then(businesses => {
setBusinesses(businesses);
});
};
return (
<>
<SearchBar searchYelp={searchYelp} />
<BusinessList business={businesses} />
</>
)
};
Then in BusinessList you need to access the passed business prop. Your current code is naming the props object businesses and then attempts to map it. It could be businesses.business.map, but by convention we name the props object props or simply destructure the props you want to use. You need to also return the Business component you are mapping to.
function BusinessList({ business }) {
return (
<div className="BusinessList">
{business.map(business => {
return <Business key={business.id} business={business} />;
})}
</div>
)
};
Same issue with the props object name in the Business component.
const Business = (props) => {
return (
<div className="Business">
<div className="image-container">
<img src={props.business.imageSrc} alt={props.business.imageSrc} />
</div>
<h2>{props.business.name}</h2>
<div className="Business-information">
<div className="Business-address">
<p>{props.business.address}</p>
<p>{props.business.city} {props.business.state} {business.zipCode}</p>
</div>
<div className="Business-reviews">
<h3>{props.business.category}</h3>
<h3 className="rating">{props.business.rating}</h3>
<p>{props.business.reviewCount} reviews</p>
</div>
</div>
</div>
)
};

BusinessList receives props, an object containing the props passed in.
The function parameter would either need to destructure it:
function BusinessList({ businesses }) { ... }
Or reference it off the props object:
function BusinessList(props) {
console.log(props.businesses)
// ...
}

Few notes:
Right now Yelp.searchYelp returns Promise<any[] | undefined>, i.e undefined is a legitimate value that the consume may get. Up to you to decide if setBusinesses(businesses) when businesses is undefined is useful or not, but in that case, handle it. Otherwise default to an empty array, setBusinesses(businesses ?? []) or throw an error.
Do not run side effects in the render phase, i.e call the api inside a useEffect:
React.useEffect(() => {
const searchYelp = Yelp.searchYelp(term, location).then(businesses => {
setBusinesses(businesses ?? [])
})
}, [term, location])
Lastly, const Business = (business) => { here business is actually the props object. You can simply destructure it const Business = ({ business }) => { to get the value directly.

React: How to trigger event in parent component when onClick event happened in child component

I have the following parent and child components. I want to run the changeBackground function every time the button in the child component (<NewQuoteButton />) is clicked but I don't know how to pass this information to the parent component. Can anyone please help?
//parent component
class App extends React.Component {
constructor(props) {
super(props)
this.state ={
primary: '',
prmaryDark: ''
}
}
changeBackground = () => {
let randomNum = Math.floor(Math.random()*backgroundColors.length)
this.setState = {
primary: backgroundColors[randomNum].main,
prmaryDark: backgroundColors[randomNum].dark
}
}
render() {
return (
<div className="App">
<QuoteBox />
</div>
);
}
}
//child component
export default function QuoteBox() {
const [newQuote, setNewQuote] = useState('');
const [author, setAuthor] = useState('');
const fetchRandomQuote = () => {
fetch(url)
// some method
}
return (
<div className="QuoteBox" >
<Text quoteText={newQuote} author={author} />
<Banner>
<Links />
<NewQuoteButton onClick={fetchRandomQuote} className="NewQuoteButton Button" />
</Banner>
</div>
);
}

//parent component
class App extends React.Component {
constructor(props) {
super(props)
this.state ={
primary: '',
prmaryDark: ''
}
}
changeBackground = () => {
let randomNum = Math.floor(Math.random()*backgroundColors.length)
this.setState = {
primary: backgroundColors[randomNum].main,
prmaryDark: backgroundColors[randomNum].dark
}
}
render() {
return (
<div className="App">
<QuoteBox handleColorChange={this.changeBackground} />
</div>
);
}
}
//child component
export default function QuoteBox(props) {
const [newQuote, setNewQuote] = useState('');
const [author, setAuthor] = useState('');
const fetchRandomQuote = () => {
props.handleColorChange();
fetch(url)
// some method
}
return (
<div className="QuoteBox" >
<Text quoteText={newQuote} author={author} />
<Banner>
<Links />
<NewQuoteButton onClick={fetchRandomQuote} className="NewQuoteButton Button" />
</Banner>
</div>
);
}

If you just want to run your changeBackground function when the button is clicked then call the function in your fetchRandomQuote function.

React onClick event in array.map()

Edit: I have included the full code for better clarity
I am not sure if this is possible. I am trying to pass an onClick event via props but the click event does not work.
The parent component looks like this:
import React from 'react'
import { getProductsById } from '../api/get'
import Product from './Product'
import { instanceOf } from 'prop-types'
import { withCookies, Cookies } from 'react-cookie'
class Cart extends React.Component {
static propTypes = {
cookies: instanceOf(Cookies).isRequired
}
constructor(props) {
super(props)
const { cookies } = props;
this.state = {
prods: cookies.get('uircartprods') || '',
collapsed: true,
total: 0,
}
this.expand = this.expand.bind(this)
this.p = [];
}
componentDidMount() {
this.getCartProducts()
}
handleClick = (o) => {
this.p.push(o.id)
const { cookies } = this.props
cookies.set('uircartprods', this.p.toString(), { path: '/' , sameSite: true})
this.setState({prods: this.p })
console.log('click')
}
getCartProducts = async () => {
let products = []
if (this.state.prods !== '') {
const ts = this.state.prods.split(',')
for (var x = 0; x < ts.length; x++) {
var p = await getProductsById(ts[x])
var importedProducts = JSON.parse(p)
importedProducts.map(product => {
const prod = <Product key={product.id} product={product} handler={() => this.handleClick(product)} />
products.push(prod)
})
}
this.setState({products: products})
}
}
expand(event) {
this.setState({collapsed: !this.state.collapsed})
}
handleCheckout() {
console.log('checkout clicked')
}
render() {
return (
<div className={this.state.collapsed ? 'collapsed' : ''}>
<h6>Your cart</h6>
<p className={this.state.prods.length ? 'hidden' : ''}>Your cart is empty</p>
{this.state.products}
<h6>Total: {this.props.total}</h6>
<button onClick={this.handleCheckout} className={this.state.prods.length ? '' : 'hidden' }>Checkout</button>
<img src="./images/paypal.png" className="paypal" alt="Paypal" />
<a className="minify" onClick={this.expand} alt="My cart"></a>
<span className={this.state.prods.length ? 'pulse' : 'hidden'}>{this.state.prods.length}</span>
</div>
)
}
}
export default withCookies(Cart)
The Product component:
import React from 'react';
class Product extends React.Component {
constructor(props) {
super(props);
this.state = {
showDetails: false,
showModal: false,
cart: []
}
this.imgPath = './images/catalog/'
}
render() {
return (
<div className="Product">
<section>
<img src={this.imgPath + this.props.product.image} />
</section>
<section>
<div>
<h2>{this.props.product.title}</h2>
<h3>{this.props.product.artist}</h3>
<p>Product: {this.props.product.product_type}</p>
<h4>${this.props.product.price}</h4>
<button className="button"
id={this.props.product.id} onClick={this.props.handler}>Add to cart</button>
</div>
</section>
</div>
)
}
}
export default Product
If I log this.props.handler I get undefined. Everything works apart from the click handler, I was wondering if it might have something to with the async function. I am very new to React, there are still some concepts I'm not sure about, so any help is appreciated.

Okay, I see a few issues here.
First, there is no need to call this.handleClick = this.handleClick.bind(this) in the constructor, because you are using an arrow function. Arrow functions do not have a this context, and instead, accessing this inside your function will use the parent this found in the Class.
Secondly, it is wrong to store components in state. Instead, map your importedProducts inside the render function.
Thirdly, the issue with your handler is that this.props.handler doesn't actually call handleClick. You will notice in the definition handler={(product) => this.handleClick} it is returning the function to the caller, but not actually calling the function.
Try this instead.
class Product extends React.Component {
constructor(props) {
super(props);
}
render() {
return (
<div>
<button className="button" id={this.props.product.id} onClick={this.props.handler}>
Add to cart
</button>
</div>
);
}
}
export default Product;
import Product from './Product'
class Cart extends React.Component {
constructor(props) {
super(props);
}
handleClick = (o) => {
console.log('click');
};
render() {
return (
<div>
{importedProducts.map((product) => {
return <Product key={product.id} product={product} handler={() => this.handleClick(product)} />;
})}
</div>
);
}
}
export default Cart;

calling grandparent method from grandchild functional component in react

I'm trying to call a simple method from the grandparent component in my child component but from some reason I can't , I tried every possible way but I think I'm missing something
here's the full code :
import React, { Component } from 'react';
import './App.css';
var todos = [
{
title: "Example2",
completed: true
}
]
const TodoItem = (props) => {
return (
<li
className={props.completed ? "completed" : "uncompleted"}
key={props.index} onClick={props.handleChangeStatus}
>
{props.title}
</li>
);
}
class TodoList extends Component {
constructor(props) {
super(props);
}
render () {
return (
<ul>
{this.props.todosItems.map((item , index) => (
<TodoItem key={index} {...item} {...this.props} handleChangeStatus={this.props.handleChangeStatus} />
))}
</ul>
);
}
}
class App extends Component {
constructor(props) {
super(props);
this.state = {
todos ,
text :""
}
this.handleTextChange = this.handleTextChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
this.handleChangeStatus = this.handleChangeStatus(this);
}
handleTextChange(e) {
this.setState({
text: e.target.value
});
}
handleChangeStatus(){
console.log("hello");
}
handleSubmit(e) {
e.preventDefault();
const newItem = {
title : this.state.text ,
completed : false
}
this.setState((prevState) => ({
todos : prevState.todos.concat(newItem),
text : ""
}))
}
render() {
return (
<div className="App">
<h1>Todos </h1>
<div>
<form onSubmit={this.handleSubmit}>
< input type="text" onChange={this.handleTextChange} value={this.state.text}/>
</form>
</div>
<div>
<TodoList handleChangeStatus={this.handleChangeStatus} todosItems={this.state.todos} />
</div>
<button type="button">asdsadas</button>
</div>
);
}
}
export default App;
The method im trying to use is handleChangeStatus() from the App component in the TodoItem component
Thank you all for your help

This line is wrong:
this.handleChangeStatus = this.handleChangeStatus(this);
//Change to this and it works
this.handleChangeStatus = this.handleChangeStatus.bind(this);

React component not refresh after search active

i have an error in my react code, my result component is not changed after change array data, in console i just see new arrays after change input, new builded data is work, but component result isnot changed.
App.jsx
import React, { Component } from 'react'
import './App.css';
import fetch from 'isomorphic-fetch'
import Header from './Header'
import Content from './Content'
import Footer from './Footer'
class App extends Component {
constructor(props) {
super(props)
this.state = {
stripdata: null,
query: ""
}
this.query = this.query.bind(this)
}
componentWillMount() {
fetch(`http://localhost:3000/data/info.json`)
.then(results => results.json())
.then(data => {
this.setState({
stripdata: data
})
})
.catch(err => {
console.log("Didn't connect to API", err)
})
}
query(e) {
e = e.trim().toLowerCase();
this.setState({
query: e
})
}
show(data, query) {
return (query.length > 0) ?
data.filter(item => { return item.fakename.stripclub.toLowerCase().match( query ) }) :
data
}
render() {
console.log(this.show(this.state.stripdata, this.state.query))
return (
<div className="App">
<Header onQuery={this.query}/>
{
(this.state.stripdata === null) ?
<div className="loading">Loading data...</div> :
<Content onResult={ this.show(this.state.stripdata, this.state.query) }/>
}
<Footer />
</div>
);
}
}
export default App;
Content.jsx
import React, { Component } from 'react'
import Result from './Result'
class Content extends Component {
constructor(props) {
super(props);
this.state = {
stripdata: this.props.onResult
};
}
componentWillMount() {
}
render() {
return (
<div className="Content">
<Result stripdata={ this.state.stripdata }/>
</div>
);
}
}
export default Content;
Finder.jsx
import React, { Component } from 'react'
class Finder extends Component {
constructor(props) {
super(props)
this.state = {}
this.handleChange = this.handleChange.bind(this)
}
handleChange(e) {
this.props.find(e.target.value)
}
render() {
return (
<div className="Finder">
<form id="search" onSubmit="">
<span>i want</span>
<input type="text"
placeholder="type who you want"
onChange={ this.handleChange }
/>
</form>
</div>
);
}
}
export default Finder;
Header.jsx
import React, { Component } from 'react'
import Finder from './Finder'
class Header extends Component {
constructor(props) {
super(props);
this.state = {
};
this.find = this.find.bind(this);
}
find(e) {
this.props.onQuery(e)
}
render() {
return (
<div className="Header">
<div className="inner">
<h2>Find with which girl you want to spend your time !!!</h2>
<Finder find={ this.find }/>
</div>
</div>
);
}
}
export default Header;
Result.jsx
import React, { Component } from 'react'
import PersonCard from './PersonCard'
class Result extends Component {
constructor(props) {
super(props);
this.state = {
stripdata: this.props.stripdata
};
}
componentWillMount() {
}
render() {
return (
<div className="result">
{
this.state.stripdata.map((item, i) => {
return <PersonCard key={i} data={item}/>
})
}
</div>
);
}
}
export default Result;
import React, { Component } from 'react'
import Facebook from 'react-icons/lib/fa/facebook'
import VK from 'react-icons/lib/fa/vk'
import Phone from 'react-icons/lib/fa/phone'
PersonCard.jsx
class PersonCard extends Component {
constructor(props) {
super(props);
this.state = {
info: this.props.data
};
}
render() {
var now = new Date().getFullYear();
return (
<div className="PersonCard">
<div className="layer one">
<div className="side left face-image">
<img src={(this.state.info.photo) ? this.state.info.photo : ""} alt="Person Pic" />
</div>
<div className="side right info">
<p><b>Fake Name:</b> { this.state.info.fakename.stripclub }</p>
<p><b>Real Name:</b> { (this.state.info.name) ? this.state.info.name : null }</p>
<p><b>Currently Workplace:</b> { (this.state.info.address.work ) ? this.state.info.address.work : null }</p>
<p><b>Age:</b> { (this.state.info.born) ? (now - this.state.info.born.slice(0, 4)) : null }</p>
<p><br /><a href={ (this.state.info.fakename.facebook) ? this.state.info.fakename.facebook.id : null } ><icon><Facebook /></icon> { (this.state.info.fakename.facebook) ? this.state.info.fakename.facebook.user : null }</a></p>
<p><br /><a href={ (this.state.info.fakename.vk) ? this.state.info.fakename.vk.id : null }><icon><VK /></icon> { (this.state.info.fakename.vk) ? this.state.info.fakename.vk.user : null }</a></p>
<p><br /><a href={ (this.state.info.phone) ? "tel:" + this.state.info.phone : null }><icon><Phone /></icon> { (this.state.info.phone) ? this.state.info.phone : null }</a></p>
</div>
</div>
<div className="layer two">
<div className="about">
<p>{ this.state.info.physical }</p>
<p>{ (this.state.info.work_days) ? 'All Week ' + this.state.info.work_days : null }</p>
</div>
</div>
</div>
);
}
}
export default PersonCard;
Please help me with with this issue.

Try to write the Content component like this:
class Content extends Component {
render() {
return (
<div className="Content">
<Result stripdata={ this.props.onResult }/>
</div>
);
}
}
And the Result component like this also:
class Result extends Component {
render() {
return (
<div className="result">
{
this.props.stripdata.map((item, i) => {
return <PersonCard key={i} data={item}/>
})
}
</div>
);
}
}
And in the PersonCard replace every reference of this.state to this.props and remove the assignment in the constructor.
I am guessing the problem is with the assignments of props into state like in the Content component:
constructor(props) {
super(props);
this.state = {
stripdata: this.props.onResult
};
}
the constructor is probably not getting called after the input values changes.
The assumption that the constructor is getting called every time the component is rendered confuses a lot of beginner react devs...
Anyway you dont need to use state in these presentational components (https://medium.com/#dan_abramov/smart-and-dumb-components-7ca2f9a7c7d0)
just use props.