Develop Reference

React Virtualized use recomputeRowHeights Method in functional components

Might be a silly question but I am trying to use the public method recomputeRowHeights specified in the documentation in a functional component while the entire react-virtualized library is based on class components.
My code for using it will be the following. It recomputes all row heights after window resizes.
window.addEventListener('resize', function(event) {
recomputeRowHeights();
console.log("recomputed!")
}, true);
Here is my wrapper for the List component:
import React from "react";
import { useState, useRef } from "react";
import { InfiniteLoader, List, WindowScroller } from 'react-virtualized';
import AutoSizer from 'react-virtualized-auto-sizer';
import Loader from "../components/decroations/Loader";
import TopMargin from "../components/decroations/TopMargin";
export default function InfiniteScroll({ getNextList, preRenderRadius }) {
const [hasNextPage, setHasNextPage] = useState(true);
const [isNextPageLoading, setIsNextPageLoading] = useState(false);
const [list, setList] = useState([{Component: <TopMargin />, height: 0.05}]);
const rowCount = hasNextPage ? list.length + 1 : list.length;
const loadMoreRows = isNextPageLoading ? () => {} : loadNextPage;
const isRowLoaded = ({index}) => !hasNextPage || index < list.length;
function rowheight({ index }){
if (!isRowLoaded({index})){
return 0.8*window.innerWidth;
}else{
return list[index].height*window.innerWidth;
}
}
const Item = ({index, key, style}) => {
if (!isRowLoaded({index})) {
return (
<div key={key} style={style} className='loaderWrapper'>
<Loader/>
</div>
)
} else {
return(
<div key={key} style={style}>
{list[index].Component}
</div>
)
};
}
function loadNextPage(){
setIsNextPageLoading(true);
getNextList(list.length - 1).then((newRows) => {
setList(list.concat(newRows))
setIsNextPageLoading(false)
}).catch(()=>{
setHasNextPage(false)
})}
return (
<InfiniteLoader
isRowLoaded={isRowLoaded}
loadMoreRows={loadMoreRows}
rowCount={rowCount}
threshold={preRenderRadius}
>
{({ onRowsRendered, registerChild }) => (
<WindowScroller>
{({ height, isScrolling, scrollTop }) => (
<AutoSizer disableHeight>
{({width}) => (
<List
autoHeight
height={height}
onRowsRendered={onRowsRendered}
ref={registerChild}
rowCount={rowCount}
rowHeight={rowheight}
rowRenderer={Item}
width={width}
isScrolling={isScrolling}
scrollTop={scrollTop}
/>
)}
</AutoSizer>)}
</WindowScroller>
)}
</InfiniteLoader>
);
}

"Warning: Encountered two children with the same key" for infinite scroll

I've implemented infinite scroll in React app, however, I get Warning: Encountered two children with the same key <...>. Keys should be unique so that components maintain their identity across updates. <...>.
If I replace key={movie.id} by key={i}, infinite scroll stops working.
This is the code of my component:
import{ useContext, useRef, useEffect } from "react";
import { Card, Grid, CardActionArea, CardMedia } from '#material-ui/core';
import FavoriteBorderIcon from '#material-ui/icons/FavoriteBorder';
import { MoviesContext } from "../../services/context";
import { Movie } from "../../services/movies.service";
import '../../App.scss';
import './Catalog.scss';
import noImage from '../../images/no-image-available.png';
import loadingSpinner from '../../images/loading-spinner.gif';
import { NavLink } from 'react-router-dom';
import useIntersectionObserver from '../../services/useIntersectionObserver';
import { fetchMovies } from "../../services/movies.service";
const posterBaseUrl = "https://image.tmdb.org/t/p/w300";
const CatalogCards = () => {
const { movies, updateMovies, searchedMovie, moviesPage, setMoviesPage, setSelectedMovie, setIsMoviePageFirstTimeOpened } = useContext(MoviesContext);
const loadingRef = useRef<HTMLDivElement | null>(null);
const entry = useIntersectionObserver(loadingRef, {})
const isVisible = !!entry?.isIntersecting;
const SetSelectedMovieId = (id: number) => {
setIsMoviePageFirstTimeOpened(true);
setSelectedMovie(id);
}
useEffect (
() => {
if ( isVisible ) {
setMoviesPage(moviesPage+1);
fetchMovies(String(moviesPage))
.then(nextPage => {
updateMovies((movies: Movie[]) => movies.concat(nextPage));
})
.catch(() => updateMovies([]))
}
},
[isVisible]
);
return (
<div >
<Grid container spacing={1} className="container-content">
{
movies.length > 0
?
movies.map((movie, i) => (
<Grid item key={movie.id}>
<NavLink to={'/movie/' + movie.id}>
<Card className="card-list" onClick={() => SetSelectedMovieId(movie.id)} >
<CardActionArea>
<CardMedia
component="img"
alt={"Poster of " + movie.title}
image={movie.poster_path ? posterBaseUrl + movie.poster_path : noImage}
title={movie.title}
/>
</CardActionArea>
</Card>
</NavLink>
</Grid>
))
:
searchedMovie ?
<div className="">Try a different phrase...</div>
:
<CardMedia
component="img"
image={loadingSpinner}
className="loading-spinner"
/>
}
</Grid>
<div ref={loadingRef}>...</div>
</div>
);
}
export default CatalogCards;
fetchMovies() method fetches info about movies from an API.
useIntersectionObserver is a custom hook that helps to check if ref={loadingRef} appears in the screen and more movies should be fetched.
How can I solve it?
Thanks!

Add items to Cart using React Context

I am new with React, I am trying to do the cart of the app that i am doing and I am having problems sending the items to the cart avoiding to have them duplicate or adding another extra item in the cart. These is the CartProvider code:
import { useState } from "react";
import CartContext from "./CartContext";
export const CartProvider = ({ children }) => {
const [list, setList] = useState();
const addCart = (varietals, quantity) => {
if (isInCart(varietals.item.id ) === -1){
setList(varietals)
}else{
list[isInCart].quantity += quantity
}
};
const isInCart = (id) => {
return list.findIndex(varietals => varietals.id === id)
};
return(
<>
<CartContext.Provider value={{list, addCart}}>
{children}
</CartContext.Provider>
</>);
};
This is the ItemDetail code which i use to display the Item:
import { useContext, useState } from "react";
import { Button, Container } from "react-bootstrap";
import { Link } from "react-router-dom";
import CartContext from "../../Context/CartContext";
import Item from "../Item/Item";
import ItemCountComponent from "../ItemCount";
const ItemDetail = ({ varietals }) => {
const [checkout, setCheckout] = useState(false);
const { list, addCart } = useContext(CartContext);
const onAdd = (count) => {
console.log("Selected ", count);
setCheckout(true);
addCart({Item: varietals, Quantity: count});
};
console.log(list)
return (
<>
<br />
<Container className="py-5 px-5 shadow">
<Item varietals={varietals} />
<div className="ml-4 mr-3">
<div className="font-italic mb-4 text-center text-muted">{varietals.description}</div>
{checkout ? <Link to='/Cart'><Button variant="info">Checkout</Button></Link> : <ItemCountComponent className="d-flex justify-content-center" onAdd={onAdd} stock={5} initial={1} />}
</div>
</Container>
</>
)
};
export default ItemDetail;
This is the Item.jsx:
import { Card, Container } from "react-bootstrap";
import "./Style.scss";
const Item = ({ varietals }) => {
return (
<>
<Container className="px-1">
<Card className="clemmy">
<Card.Img variant="top" src={varietals.pictureUrl} className="shadow"/>
<Card.Body>
<Card.Title className="d-flex justify-content-center text-muted">
{varietals.title}
</Card.Title>
<Card.Subtitle className="d-flex justify-content-center text-muted">
${varietals.price}
</Card.Subtitle>
</Card.Body>
</Card>
</Container>
</>
)
};
export default Item;
This is the ItemListContainer.jsx:
import { useEffect, useState } from "react";
import { useParams } from "react-router-dom";
import aimara from "../../aimara";
import ItemList from "../../Components/ItemList/ItemList";
const ItemListContainer = () => {
const [varietals, setVarietals] = useState([])
const { categoryId } = useParams();
useEffect(() => {
const myPromise = new Promise((resolve, reject) => {
if (categoryId) {
const products = aimara.filter((producto) => {
return producto.category.toString() === categoryId;
});
resolve(products);
} else resolve(aimara);
});
myPromise.then((result) => setVarietals(result));
}, [categoryId]);
return <ItemList varietals={varietals} />
};
export default ItemListContainer;
The error that I am seeing is "TypeError: Cannot read property 'id' of undefined"
If there is someone that could help me would be much appreciate it. Also, in case you need some extra file let me know and I update the post as quickly as I can. Cheers

I need the below code written as React Hooks. Is it possible to write it so?

I am using react hooks mostly in my current app. I need the below code expressed as react hooks, without the this.state and this.props. My current app is expressed entirely as React Hooks. If you see it closely, the below code is writing out SQL query code with the click of a button. I need that functionality in my current app, but I don't know how to assimilate that in my app. Any ideas?
import React from 'react';
import { Row, Col, Tabs, Spin, Card, Alert, Tooltip, Icon, Button } from 'antd';
import cubejs from '#cubejs-client/core';
import { QueryRenderer } from '#cubejs-client/react';
import sqlFormatter from "sql-formatter";
import JSONPretty from 'react-json-pretty';
import Prism from "prismjs";
import "./css/prism.css";
const HACKER_NEWS_DATASET_API_KEY = 'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpIjozODU5NH0.5wEbQo-VG2DEjR2nBpRpoJeIcE_oJqnrm78yUo9lasw'
class PrismCode extends React.Component {
componentDidMount() {
Prism.highlightAll();
}
componentDidUpdate() {
Prism.highlightAll();
}
render() {
return (
<pre>
<code className='language-javascript'>
{ this.props.code }
</code>
</pre>
)
}
}
const tabList = [{
key: 'code',
tab: 'Code'
}, {
key: 'sqlQuery',
tab: 'Generated SQL'
}, {
key: 'response',
tab: 'Response'
}];
class CodeExample extends React.Component {
constructor(props) {
super(props);
this.state = { activeTabKey: 'code' };
}
onTabChange(key) {
this.setState({ activeTabKey: key });
}
render() {
const { codeExample, resultSet, sqlQuery } = this.props;
const contentList = {
code: <PrismCode code={codeExample} />,
response: <PrismCode code={JSON.stringify(resultSet, null, 2)} />,
sqlQuery: <PrismCode code={sqlQuery && sqlFormatter.format(sqlQuery.sql())} />
};
return (<Card
type="inner"
tabList={tabList}
activeTabKey={this.state.activeTabKey}
onTabChange={(key) => { this.onTabChange(key, 'key'); }}
>
{ contentList[this.state.activeTabKey] }
</Card>);
}
}
const Loader = () => (
<div style={{textAlign: 'center', marginTop: "50px" }}>
<Spin size="large" />
</div>
)
const TabPane = Tabs.TabPane;
class Example extends React.Component {
constructor(props) {
super(props);
this.state = { showCode: false };
}
render() {
const { query, codeExample, render, title } = this.props;
return (
<QueryRenderer
query={query}
cubejsApi={cubejs(HACKER_NEWS_DATASET_API_KEY)}
loadSql
render={ ({ resultSet, sqlQuery, error, loadingState }) => {
if (error) {
return <Alert
message="Error occured while loading your query"
description={error.message}
type="error"
/>
}
if (resultSet && !loadingState.isLoading) {
return (<Card
title={title || "Example"}
extra={<Button
onClick={() => this.setState({ showCode: !this.state.showCode })}
icon="code"
size="small"
type={this.state.showCode ? 'primary' : 'default'}
>{this.state.showCode ? 'Hide Code' : 'Show Code'}</Button>}
>
{render({ resultSet, error })}
{this.state.showCode && <CodeExample resultSet={resultSet} codeExample={codeExample} sqlQuery={sqlQuery}/>}
</Card>);
}
return <Loader />
}}
/>
);
}
};
export default Example;

It's quite easy to convert a class to a functional component.
Remember these steps:
class => const
// Class
export class Example
// FC
export const Example
componentLifeCycles => useEffect
// Class lifecycle
componentDidMount() {
// logic here
}
// FC
useEffect(() => {
// logic here
})
render => return
// Class
render () {
return (<Component/>)
}
// FC
return (<Component />)`
constructor => useState
// Class
constructor(props) {
this.state.val = props.val
}
// FC
const [val, setVal] = useState(props.val)
setState => second arg from useState
// Class
constructor() {
this.state.val = val // constructor
}
this.setState({ val }) // class
// FC
const[val, setVal] = useState(null)
setVal("someVal")
TLDR: Solution
import React, { useEffect, useState } from "react"
import { Tabs, Spin, Card, Alert, Button } from "antd"
import cubejs from "#cubejs-client/core"
import { QueryRenderer } from "#cubejs-client/react"
import sqlFormatter from "sql-formatter"
import Prism from "prismjs"
import "./css/prism.css"
const HACKER_NEWS_DATASET_API_KEY =
"eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpIjozODU5NH0.5wEbQo-VG2DEjR2nBpRpoJeIcE_oJqnrm78yUo9lasw"
const PrismCode: React.FC = ({ code }) => {
useEffect(() => {
Prism.highlightAll()
})
return (
<pre>
<code className="language-javascript">{code}</code>
</pre>
)
}
const TabList = [
{
key: "code",
tab: "Code",
},
{
key: "sqlQuery",
tab: "Generated SQL",
},
{
key: "response",
tab: "Response",
},
]
const CodeExample: React.FC = ( { codeExample, resultSet, sqlQuery } ) => {
const [activeTabKey, setActiveTab] = useState("code")
const onTabChange = (key) => setActiveTab(key)
const contentList = {
code: <PrismCode code={codeExample} />,
response: <PrismCode code={JSON.stringify(resultSet, null, 2)} />,
sqlQuery: (
<PrismCode code={sqlQuery && sqlFormatter.format(sqlQuery.sql())} />
),
}
return (
<Card
type="inner"
tabList={TabList}
activeTabKey={activeTabKey}
onTabChange={(key) => {
onTabChange(key)
}}
>
{contentList[activeTabKey]}
</Card>
)
}
const Loader = () => (
<div style={{ textAlign: "center", marginTop: "50px" }}>
<Spin size="large" />
</div>
)
const TabPane = Tabs.TabPane
const Example: React.FC = ({ query, codeExample, render, title }) => {
const [showCode, toggleCode] = useState(false)
return (
<QueryRenderer
query={query}
cubejsApi={cubejs(HACKER_NEWS_DATASET_API_KEY)}
loadSql
render={({ resultSet, sqlQuery, error, loadingState }) => {
if (error) {
return (
<Alert
message="Error occured while loading your query"
description={error.message}
type="error"
/>
)
}
if (resultSet && !loadingState.isLoading) {
return (
<Card
title={title || "Example"}
extra={
<Button
onClick={() =>
toggleCode(!this.state.showCode)
}
icon="code"
size="small"
type={showCode ? "primary" : "default"}
>
{showCode ? "Hide Code" : "Show Code"}
</Button>
}
>
{render({ resultSet, error })}
{showCode && (
<CodeExample
resultSet={resultSet}
codeExample={codeExample}
sqlQuery={sqlQuery}
/>
)}
</Card>
)
}
return <Loader />
}}
/>
)
}
export default Example

Rendering multiple input fields causing lag after 200 items

I have a project where i can have n-number of input field. After when i add 200 items, it starts lagging after that. Demo : https://testcreate.vivekneel.now.sh/create (To test: Focus last input and try pressing enter button to create new input)
Source Code. : https://github.com/VivekNeel/Create-Test
This is my main container :
import React, { useState } from "react";
import CreateTerms from "./CreateTerms";
import { initTerms, contructTermObject } from "./utils";
import { Container } from "#material-ui/core/";
const CreateStudySetContainer = () => {
const [terms, setTerms] = useState(initTerms);
const [inputIdToFocus, setInputIdToFocus] = useState(null);
const handleCreateTerm = () => {
const newTerm = contructTermObject(terms.length + 1, 2);
const newTerms = [...terms, newTerm];
setInputIdToFocus(terms.length + 1);
setTerms(newTerms);
};
console.log("....rendering");
return (
<Container maxWidth={"md"}>
<CreateTerms
terms={terms}
inputIdToFocus={inputIdToFocus}
createTerm={handleCreateTerm}
/>
;
</Container>
);
};
export default CreateStudySetContainer;
This the CreateTerms code :
import React from "react";
import CreateFacts from "./CreateFacts";
import { withStyles, Card } from "#material-ui/core/";
import ContentItemRow from "./ContentItemRow";
const styles = () => ({
card: {
marginBottom: 16,
},
});
const CreateTerms = (props) => {
const { terms, classes, createTerm, inputIdToFocus } = props;
return (
<div className={classes.container}>
{terms.map(({ node: { term } }, index) => {
return (
<Card key={term.id} className={classes.card}>
<p>{index}</p>
<ContentItemRow
autoFocus={term.id === inputIdToFocus}
createTerm={createTerm}
term={term}
/>
;
</Card>
);
})}
</div>
);
};
export default withStyles(styles)(CreateTerms);
This is ContentItemRow :
import React from "react";
import CreateFacts from "./CreateFacts";
import { withStyles } from "#material-ui/core/";
import ContentEditor from "./ContentEditor";
const styles = {
container: {
display: "flex",
flexDirection: "row",
alignItems: "center",
justifyContent: "flex-start",
},
term: {
marginRight: 16,
flex: 1,
},
facts: {
flex: 1,
},
};
const ContentItemRow = (props) => {
const { term, classes, createTerm, autoFocus } = props;
return (
<div className={classes.container}>
<div className={classes.term}>
<ContentEditor
autoFocus={autoFocus}
createTerm={createTerm}
placeholder={"New term"}
/>
</div>
<div className={classes.facts}>
{term.facts.map(({ fact }) => {
return (
<ContentEditor
key={fact.id}
createTerm={createTerm}
placeholder={"New fact"}
/>
);
})}
</div>
</div>
);
};
export default withStyles(styles)(ContentItemRow);
This is ContentEditor :
import React from "react";
import { TextField } from "#material-ui/core/";
const ContentEditor = (props) => {
const { placeholder, createTerm, autoFocus } = props;
const handleOnKeyDown = (event) => {
const { keyCode } = event;
if (keyCode === 13) {
createTerm();
}
};
return (
<TextField
onKeyDown={handleOnKeyDown}
fullWidth
autoFocus={autoFocus}
placeholder={placeholder}
/>
);
};
export default ContentEditor;
When debugging, I noticed that dom updates only the last div which gets added. I don't know where the lagging is coming from.

Not sure if this will work but you can try the following:
const ContentItemRow = React.memo(function ContentItemRow (props) => {
And to prevent re creating the create term handler:
const handleCreateTerm = useCallback(() => {
setTerms((terms) => {
const newTerm = contructTermObject(
terms.length + 1,
2
);
const newTerms = [...terms, newTerm];
setInputIdToFocus(terms.length + 1);
return newTerms;
});
}, []);