Develop Reference

React suggestions Input setting state

im prety new to React and im trying to use an autocomplete input. Im having problems getting the value from it and clearing the input values after submitting. Any help would be greatly appretiated.
import React, { Component, Fragment } from "react";
import PropTypes from "prop-types";
import "../AutoComplete/styles.css"
class Autocomplete extends Component {
static propTypes = {
suggestions: PropTypes.instanceOf(Array)
};
static defaultProps = {
suggestions: [],
};
constructor(props) {
super(props);
this.state = {
// The active selection's index
activeSuggestion: 0,
// The suggestions that match the user's input
filteredSuggestions: [],
// Whether or not the suggestion list is shown
showSuggestions: false,
// What the user has entered
userInput: this.props.value ? this.props.value : "",
};
}
//Order by 'code'
generateSortFn(prop, reverse) {
return function (a, b) {
if (a[prop] < b[prop]) return reverse ? -1 : 1;
if (a[prop] > b[prop]) return reverse ? 1 : -1;
return 0;
};
}
onChange = e => {
const { suggestions } = this.props;
const userInput = e.currentTarget.value;
// Filter our suggestions that don't contain the user's input
const filteredSuggestions = suggestions.sort(this.generateSortFn('code', true)).filter(
(suggestion, i) => {
let aux = suggestion.descrp+"- "+suggestion.code
return aux.toLowerCase().indexOf(userInput.toLowerCase()) > -1
}
);
this.setState({
activeSuggestion: 0,
filteredSuggestions,
showSuggestions: true,
userInput: e.currentTarget.value
});
};
onClick = e => {
this.setState({
activeSuggestion: 0,
filteredSuggestions: [],
showSuggestions: false,
userInput: e.currentTarget.innerText
});
};
onKeyDown = e => {
const { activeSuggestion, filteredSuggestions } = this.state;
// User pressed the enter key
if (e.keyCode === 13) {
this.setState({
activeSuggestion: 0,
showSuggestions: false,
userInput: filteredSuggestions[activeSuggestion].code+" - "+filteredSuggestions[activeSuggestion].descrp
});
}
// User pressed the up arrow
else if (e.keyCode === 38) {
if (activeSuggestion === 0) {
return;
}
this.setState({ activeSuggestion: activeSuggestion - 1 });
}
// User pressed the down arrow
else if (e.keyCode === 40) {
if (activeSuggestion - 1 === filteredSuggestions.length) {
return;
}
this.setState({ activeSuggestion: activeSuggestion + 1 });
}
};
render() {
const {
onChange,
onClick,
onKeyDown,
state: {
activeSuggestion,
filteredSuggestions,
showSuggestions,
userInput
}
} = this;
let suggestionsListComponent;
if (showSuggestions && userInput) {
if (filteredSuggestions.length) {
suggestionsListComponent = (
<ul className="suggestions">
{filteredSuggestions.map((suggestion, index) => {
let className="";
// Flag the active suggestion with a class
if (index === activeSuggestion) {
className = "suggestion-active";
}
return (
<li className={className} key={suggestion.code} onClick={onClick}>
{suggestion.code+" - "+suggestion.descrp}
</li>
);
})}
</ul>
);
} else {
suggestionsListComponent = (
<div className="no-suggestions">
<p>Sin sugerencias</p>
</div>
);
}
}
and the return (this is where i think im wrong)
return (
<Fragment>
<label htmlFor="autocomplete-input" className="autocompleteLabel">{this.props.label}</label>
<div className="centerInput">
<input
className="autocomplete-input"
type="text"
onChange={onChange}
onKeyDown={onKeyDown}
defaultValue={this.props.initState}
value= {/* this.props.value ? this.props.value : */ userInput}
placeholder={this.props.placeholder}
selection={this.setState(this.props.selection)}
/>
{suggestionsListComponent}
</div>
</Fragment>
);
}
}
export default Autocomplete;
What I want is to use this component in different pages, so im passing the "selection" prop and setting the state there.
The input is working correctly (searches, gets the value and shows/hide the helper perfectly). The problem is i cant reset this inputs clearing them, and i suspect the error is in here.
I get the following warning (even with it somewhat functioning)
Cannot update during an existing state transition (such as within `render`). Render methods should be a pure function of props and state.
This is the Component usage with useState:
<Autocomplete label='Out cost Center:' placeholder='Set the out cost center' suggestions={dataCostCenterHelper} selection={(text) => setOutCostCenter(text.userInput)} value={outCostCenter} />
and last this is how im tryin to clear the state that is set in "selection":
const clearData = async () => {
setOutCostCenter('-');
// other inputs with the same component
setOutVendor('-');
setOutRefNumber('-');
}
This gets called inside the function that handles the button submitting the form.
Thanks in advance!

Looking at the code you posted this line might be the problem:
selection={this.setState(this.props.selection)}
You are updating state directly inside the render method, this is not recommended.
Try using a selection prop or state field and update the prop inside a componenteDidMount life cycle
selection={this.state.selection}

Executing a loop in React class component

I'm building a pagination component and I'm struggling to execute a for loop so I can dynamically generate the pages. I initially had a function component, but I want to switch it to a class component so I can manage state in it. (I know, I can use hooks, but Im practicing class components at the moment).
I initially added the for loop in the render method but it is executing the loop twice because the component ir rendering twice. Then, I tried componentDidMount() but it doesn't do anything... then used componentWillMount() and it worked. However, I know this could be bad practice.
Any ideas? See below the component with componentDidMount()
import React, { Component } from 'react';
import styles from './Pagination.module.css';
class Pagination extends Component {
state = {
pageNumbers: [],
selected: '',
};
componentDidMount() {
for (
let i = 1;
i <= Math.ceil(this.props.totalDogs / this.props.dogsPerPage);
i++
) {
this.state.pageNumbers.push(i);
}
}
classActiveForPagineHandler = (number) => {
this.setState({ selected: number });
};
render() {
return (
<div className={styles.PaginationContainer}>
<nav>
<ul className={styles.PageListHolder}>
{this.state.pageNumbers.map((num) => (
<li key={num}>
<a
href="!#"
className={
this.state.selected === num
? styles.Active
: styles.PageActive
}
onClick={() => {
this.props.paginate(num);
// this.props.classActiveForPagineHandler(num);
}}
>
{num}
</a>
</li>
))}
</ul>
</nav>
</div>
);
}
}
export default Pagination;

You better push all the numbers into array and then update pageNumbers state. this.state.pageNumbers.push(i); does not update state directly, you need use setState after your calculation completes.
componentDidMount() {
const { pageNumbers = [] } = this.state
const { totalDogs, dogsPerPage } = this.props
for (let i = 1; i <= Math.ceil(totalDogs / dogsPerPage); i++) {
pageNumbers.push(i);
}
this.setState({ pageNumbers })
}
Demo link here

you should not update state like this :
this.state.pageNumbers.push(i);
do this:
this.setState((s) => {
return {
...s,
pageNumbers: [...s.pageNumbers, i]
}
})

Do not mutate state directly in react component. Use setState for all updates.
componentDidMount() {
const pageNumbers = [];
for (
let i = 1;
i <= Math.ceil(this.props.totalDogs / this.props.dogsPerPage);
i++
) {
pageNumbers.push(i);
}
this.setState({ pageNumbers });
}
Alternatively, you can simplify the code using Array.from for this case.
componentDidMount() {
this.setState({
pageNumbers: Array.from(
{ length: Math.ceil(this.props.totalDogs / this.props.dogsPerPage) },
(_, i) => i + 1
),
});
}

React state returns only one element

I'm trying to modify state and take the new state to render.
When I click and modified(added {isClicked: true} to array), console.log(this.state.listOfQuotes) inside onClicked function returns modified the full array of state(which I want to use)
but after render, console.log(this.state.listOfQuotes) returns only one clicked element and not even modified one...
Any help/hint much appreciated!
Here is my code
import React from "react";
export class Quotes extends React.Component {
constructor(props) {
super(props);
this.state = { listOfQuotes: [] };
this.vote = this.vote.bind(this);
this.onClicked = this.onClicked.bind(this);
}
componentDidMount() {
const url = "https://programming-quotes-api.herokuapp.com/quotes";
fetch(url)
.then(res => res.json())
.then(quote => {
this.setState({
listOfQuotes: quote
});
});
}
onClicked(id) {
const quotes = [...this.state.listOfQuotes];
const clickedQuote = quotes.findIndex(quote => quote.id === id);
console.log("onclicked", clickedQuote);
const newArray = { ...quotes[clickedQuote], isClicked: true };
console.log(newArray);
this.setState(prevState => ({
listOfQuotes: [
...prevState.listOfQuotes.splice(clickedQuote, 1, newArray)
]
}));
console.log(this.state.listOfQuotes); ----------> this one returns what i want
}
render() {
console.log(this.state.listOfQuotes); -----------> i want to have same result as above state
return (
<div className="quotes">
<div>
{this.state.listOfQuotes.map((quote, idx) => (
<div key={idx}>
<div onClick={() => this.onClicked(quote.id)}>
{!quote.isClicked ? (
<div className="before-clicked">{quote.en}</div>
) : (
<div className="after-clicked">{quote.en}</div>
)}
</div>
<div>By {quote.author}</div>
<div>Rating {quote.rating}</div>
<div className="vote">
<span>{quote.numberOfVotes}</span>
</div>
</div>
))}
</div>
</div>
);
}
}

There is a problem with your onClicked method.
It is not modifying the array correctly.
In my opinion, this is how it could have done.
onClicked(id) {
let quotes = [...this.state.listOfQuotes];
const clickedQuoteIndex = quotes.findIndex(quote => quote.id === id);
// Modify the object on the found index and assign true to "isClicked"
quotes[clickedQuoteIndex].isClicked = true;
// And then setState with the modified array
// Since setState is async, so the console shouldn't be called immediately
// but rather in the callback
this.setState({ listOfQuotes: quotes }, () => {
console.log(this.state.listOfQuotes);
});
}

React Native - Unable to pass CheckBox value to another screen

I'm here to ask what's your idea to properly pass a CheckBox value to other screen?
Example, if a user checks a CheckBox then proceed to the Next Screen the value of the CheckBox should be displayed in that screen.
But in my code, my console.log gives an output of false(I don't understand why) and once I get to the next screen the state doesn't really pass because it's display is blank.
Here's my code
export default class tables extends Component {
constructor(props){
super(props)
this.state = {
...
check: {},
tbl_Merge: []
}
}
proceed_TO_Category = () => {
this.props.navigation.navigate('Category', {
userName : this.state.userName,
DineIn : this.state.DineIn,
tbl : this.state.tbl,
tbl_2nd : this.state.tbl_2nd,
tbl_Merge : this.state.tbl_Merge
});
console.log("CHECK ======> "+ this.state.tbl_Merge);
}
checkBox_Test = (table_NO) => {
const tbl_Merge = this.state.tbl_Merge;
const checkCopy = {...this.state.check}
if (checkCopy[table_NO]) {
checkCopy[table_NO] = false;
} else {
checkCopy[table_NO] = true;
}
this.setState({ check: checkCopy });
this.setState({ tbl_Merge: table_NO == this.state.tbl_Merge });
}
render() {
return(
<View>
....
<Flatlist
....
<CheckBox
value = { this.state.check[item.tbl_id] }
onChange = {() => this.checkBox_Test(item.tbl_id) }
/>
....
/>
....
<View>
<TouchableOpacity
onPress = {() => this.proceed_TO_Category()}>
<Text>Categories</Text>
</TouchableOpacity>
</View>
<View/>
)
}
}
Screen shot of Console.log in my proceed_TO_Category.

checkBox_Test = (table_NO) => {
const tbl_Merge = this.state.tbl_Merge;
const checkCopy = {...this.state.check}
if (checkCopy[table_NO]) {
checkCopy[table_NO] = false;
} else {
checkCopy[table_NO] = true;
}
this.setState({ check: checkCopy, tbl_Merge: table_NO == this.state.tbl_Merge }); // 1. Edit
}
Edit: We should not use setState consecutively. Because setState is async func. If you want to call a function after setState process with the help of callback function,setState(update, callback);
you defined tbl_Merge as an array, but while you set it to state, you set it as a boolean.

React JS - onClick is creating an object within an object in setState

I am making a React App for Ping Pong Tournament. Code below.
import React, { Fragment, Component } from "react";
import Button from "./Button";
const playerStylingTrue = {
backgroundColor: "#26C281"
};
class Matches extends Component {
constructor(props) {
super(props);
this.state = {
numOfRounds: "",
numberOfPlayers: this.props.numberOfPlayers,
player1Clicked: false,
player2Clicked: false,
winners: []
}
this.onClickWinnerP1 = this.onClickWinnerP1.bind(this);
this.onClickWinnerP2 = this.onClickWinnerP2.bind(this);
}
numberOfRounds() {
const { numberOfPlayers } = this.state;
const numOfRounds = Math.ceil((Math.log(numberOfPlayers)) /
(Math.log(2)));
this.setState = ({
numOfRounds: numOfRounds
})
};
onClickWinnerP1(player1) {
let player1String = player1.toString()
let { winners } = this.state;
// let findWinner = winners.find(o => o.player1String === player1);
//winners.includes(findWinner) ? null :
this.setState({
player1Clicked: !this.state.player1Clicked,
player2Clicked: this.state.player1Clicked,
winners: [{...winners, player1String, winner:true}]
})
};
onClickWinnerP2(player2) {
let player2String = player2.toString()
let { winners } = this.state;
this.setState({
player2Clicked: !this.state.player2Clicked,
player1Clicked: this.state.player2Clicked,
winners: winners.includes(player2String) ? [...winners] :
[{...winners, player2String, winner:true}]
})
};
render() {
const { pairs } = this.props;
const { winners } = this.state;
console.log(winners)
return (
<Fragment>
<Button
onClick={this.props.onClick}
className={"btn btn-success"}
buttonText={"Create Random Matches 🏓"}
/>
{pairs.map((pair, i) => {
let player1 = [...pair];
let player2 = player1.splice(0, Math.ceil(player1.length /
2));
return (
<div key={i} className="fixture-div">
<ul className="list-unstyled fixture-list">
<li
style={ this.state.winners.includes(player1) ? playerStylingTrue : null}
onClick={() => this.onClickWinnerP1(player1)}
className="hvr-grow fixture">
{player1}
</li>
<span>vs</span>
<li
style={this.state.winners.includes(player2) ? playerStylingTrue : null}
onClick={() => this.onClickWinnerP2(player2)}
className="hvr-grow fixture">
{player2}
</li>
</ul>
</div>
)
})
}
{/* <TwoRounds pairs={pairs}/> */}
</Fragment>
);
}
}
export default Matches;
Currently the onClickWinnerP1 successfully add an object to the state, containing the correct details. However if I click twice or use onClickWinnerP2, is also adds an object to the state, but nested within the object that is already there. And so on, so on. Just keeps nesting.
Any help would be greatly appreciated!

The way you are doing setState in noOfRounds function isn't correct. Instead you should do like below
this.setState({
numOfRounds: numOfRounds
})
Regarding your issue, do something like below in onClickWinnerP1 function to push objects into an array
this.setState(prevState => ({
player1Clicked: !this.state.player1Clicked,
player2Clicked: this.state.player1Clicked,
winners: [...prevState.winners, {player1String, winner:true}]
}))
AND in onClickWinnerP2 function do something like below to push objects into an array
this.setState(prevState => ({
player2Clicked: !this.state.player2Clicked,
player1Clicked: this.state.player2Clicked,
winners: prevState.winners.includes(player2String) ? [...prevState.winners] :
[...prevState.winners, {player2String, winner:true}]
}))