Hello I am trying to implement a very simple functionality that would update my state based on the value passed into a function. The function is declared in my parent component, is passed to my child component via props and it is being called on a child component.
I keep getting this error on the console:
Warning: setState(...): Cannot update during an existing state transition (such as within render or another component's constructor). Render methods should be a pure function of props and state; constructor side-effects are an anti-pattern, but can be moved to componentWillMount.
Here is my code:
Parent component
import React, {Component } from "react";
import Sidebar from './Sidebar';
import Content from './Content';
class Tabs extends Component {
constructor(props){
super(props);
this.state={
message:'Select a name from the tabs menu'
};
this.handleName = this.handleName.bind(this);
}
componentWillMount () {
if ('pluginLoaded' in window) {
(window).pluginLoaded('tabs', function (port: any, context: any) {
// Future work should interact with the message channel here
});
}
}
handleName(value){
if (value === 'Vanessa'){
console.log(`${value} in da house `)
this.setState({
message: 'Vanessa means "butterfly"'
})
}
}
render() {
return (
<div className="Tabs">
<Sidebar
handleName = {this.handleName}
/>
<Content
message = {this.state.message}
/>
</div>
)
}
}
export default Tabs;
Child component
import React from 'react';
const Sidebar = (props) =>{
let Vanessa= 'Vanessa';
let Paola = 'Paola';
return(
<div className="Sidebar">
<h1>Tabs</h1>
<ul>
<li><a onClick={props.handleName(Vanessa)}>Vanessa</a></li>
<li><a onClick={props.handleName(Paola)}>Paola</a></li>
</ul>
</div>
)
}
export default Sidebar;
Instead of:
<li><a onClick={props.handleName(Vanessa)}>Vanessa</a></li>
try:
<li><a onClick={() => props.handleName(Vanessa)}>Vanessa</a></li>
Related
Hello I'm trying to change the state when I click the button and only when the state changes run createBattle() but the state does not change after I click the button.
At the beginning I set the state to false. The button is in Form.js with an event onClick={this.handleClick}. Then the event handleClick should set the state to true and when the state changes createBattle() in Battle.js should render the table.
Please tell me what am I doing wrong ?
Thanks
App.js
import React from "react";
import Titles from "./Components/Title";
import Form from "./Components/Form";
import Battle from "./Components/Battle";
import "./App.css";
class App extends React.Component{
state = {
startPosition : false
}
render(){
return(
<div>
<header>
<div className="meniu"></div>
</header>
<div className="wrapper">
<div className="main">
<div className="container">
<div className="title-container">
<Titles />
<div className="info">
<Form startPosition={this.state.startPosition} />
</div>
</div>
<div className="form-container">
<Battle startPosition={this.state.startPosition}/>
</div>
</div>
</div>
</div>
</div>
);
}
};
export default App;
Battle.js
import React, {Component} from "react";
import Square from "./Square";
class Battle extends Component{
constructor(){
super();
}
createBattle = () => {
let table=[];
for (let i=1; i<=10; i++){
let children = [];
for (let j=1; j<=10; j++){
children.push(<Square />)
}
table.push(<div className="board-row">{children}</div>)
}
return table;
}
render(){
console.log(this.props);
return(
<div className="center">
{this.startPosition && this.props.createBattle()}
</div>
);
}
}
export default Battle;
Form.js
import React from "react";
class Form extends React.Component{
constructor(){
super();
}
handleClick = () =>{
this.setState({
startPosition: true
});
};
render(){
console.log(this.props);
return(
<div>
<button className="button" onClick={this.handleClick}>START</button>
</div>
);
}
};
export default Form;
The state and props of a given component is not shared across other components.
If you need to communicate between components you mostly have 2 different options :
Move state logic to a common parent and pass this state as props in child components (Note that you may also need to pass some functions to allow to interact with this parent state from the child components)
Use a common state, with a framework like Redux (widely used in complex projects)
React does not support sharing of state or props values.
So you should use any of the following
React Redux
AsyncStorage
I am trying to update state of my parent component through child component via setState. below is my parent component:
Fulllayout
import React from 'react';
import { Route, Switch, Redirect } from 'react-router-dom';
import Header from '../components/header/header.jsx';
import Customizer from '../components/customizer/customizer';
import { Navbar, NavbarBrand, Collapse } from 'reactstrap';
export const settings = {
navbarbg: 'skin1',
sidebarbg: 'skin6',
logobg: 'skin6'
}
class Fulllayout extends React.Component {
constructor(props) {
super(props);
this.state = {
settings: settings
};
}
render() {
return (
<div id="main-wrapper">
<header data-navbarbg={this.state.settings.navbarbg}>
<Navbar expand="md" className={}></Navbar>
</header>
<div className="page-wrapper d-block"></div>
<Customizer />
</div>
);
}
}
export default Fulllayout;
in parent i have defined one constant settings which is exported. It is also given in the this.state. and in header, there is an attribute data-navbarbg={this.state.settings.navbarbg}.
I wanted to change its value dynamically. So, i have one customizer which is imported in parent as a child. Below is the child component:
customizer
import React from 'react';
import { settings } from '../../layouts/fulllayout';
import update from 'immutability-helper';
class Customizer extends React.Component {
constructor(props) {
super(props);
this.navbarbgChange = this.navbarbgChange.bind(this);
this.state = {
settings: settings
};
}
navbarbgChange(e) {
var skin = e.currentTarget.dataset.navbarbg;
var abc = update(this.state.settings, {
navbarbg: { $set: skin }
});
this.setState({ settings: abc });
}
render() {
return (
<aside className="customizer" id="customizer">
<a className="service-panel-toggle text-white"></a>
<div className="customizer-body pt-3">
<div className="mt-3 border-bottom px-3">
<ul className="theme-color mb-2">
<li><a data-navbarbg="skin1" onClick={this.navbarbgChange}></a></li>
</ul>
</div>
</div>
</aside>
);
}
}
export default Customizer;
From customizer, by clicking on color, i wanted to setState of parent to the value given in data-navbarbg attribute.
If i put this code in parent jsx file, it is working fine but for some reasons, this files should be kept separated.
So, what is missing in my code? or the whole approach is wrong? Thanks.
Is there a reason for navbarbgChange to be defined in Customizer?
You could consider moving navbarbgChange to Fulllayout instead.
That way you can do
<li><a data-navbarbg="skin1" onClick={this.props.navbarbgChange}></a></li>
This will ensure that the Fulllayout has the updated background in its state. This also ensures that there is good separation of concerns since settings is defined in the parent and not the child component
In react you can always pass methods from parent to child. Let's write method in the parent to change the state of the parent from the child like this.
class Fulllayout extends React.Component {
constructor(props) {
super(props);
this.state = {
settings: settings
};
}
// This will be passed to the child component
changeForCustomizerState() {
this.setState({
settings: abc
});
}
changeForHeaderState() {
this.setState({
settings: abc
});
}
render() {
return (
<div id="main-wrapper">
<header chageNavbarbg={this.changeForHeaderState}>
<Navbar expand="md" className={}></Navbar>
</header>
<div className="page-wrapper d-block"></div>
<Customizer chageNavbarbg={this.changeForCustomizerState} />
</div>
);
}
}
Then onClick on the child just call the parent method from the child which is passed from the parent.
render() {
return (
<aside className="customizer" id="customizer">
<a className="service-panel-toggle text-white"></a>
<div className="customizer-body pt-3">
<div className="mt-3 border-bottom px-3">
<ul className="theme-color mb-2">
<li><a data-navbarbg="skin1" onClick={this.props.chageNavbarbg}></a></li>
</ul>
</div>
</div>
</aside>
);
}
The state update can be done in Parent from Child using callbacks. Check below code for better understanding
Fulllayout:
updateState = (skin) => {
this.setState({
settings.navbarbg: skin
});
}
render(){
return(
<div>
<Customizer updateState={this.updateState}
</div>
);
}
And in your customizer
navbarbgChange(e){
const skin = e.currentTarget.dataset.navbarbg;
this.props.updateState(skin);
}
OR
Fulllayout:
updateState = (e) => {
const skin = e.currentTarget.dataset.navbarbg;
this.setState({
settings.navbarbg: skin
});
}
render(){
return(
<div>
<Customizer updateState={this.updateState}
</div>
);
}
Customizer: directly pass parent function to onClick
<li><a data-navbarbg="skin1" onClick={this.props.updateState}></a></li>
Also stop using var, and start using let and const mostly. ECMASCRIPT itself argues to avoid using var because of its window scope.
I am using the react-chat-widget and trying to call a function in the base class of my application from a custom component rendered by the renderCustomComponent function of the widget.
Here is the code for the base class:
import React, { Component } from 'react';
import { Widget, handleNewUserMessage, addResponseMessage, addUserMessage, renderCustomComponent } from 'react-chat-widget';
import 'react-chat-widget/lib/styles.css';
import Reply from './Reply.js';
class App extends Component {
handleNewUserMessage = (newMessage) => {
renderCustomComponent(Reply, this.correct);
}
correct = () => {
console.log("success");
}
render() {
return (
<div className="App">
<Background />
<Widget
handleNewUserMessage={this.handleNewUserMessage}
/>
</div>
);
}
}
export default App;
And here is the code for the custom component Reply:
import React, { Component } from 'react';
import { Widget, addResponseMessage, renderCustomComponent, addUserMessage } from 'react-chat-widget';
class Reply extends Component {
constructor(props) {
super(props);
}
sendQuickReply = (reply) => {
console.log(this.props); //returns empty object
//this.props.correct(); <-- should be called
};
render() {
return (
<div className="message">
<div key="x" className={"response"}onClick={this.sendQuickReply.bind(this, "xx")}>xx</div>
</div>)
}
}
export default Reply;
According to ReactJS call parent method this should work. However, when I print the this.props object it is empty, although the documentation of the renderCustomComponent method states that the second argument of the component to render are the props that the component needs (in this case the parent class function).
Where have I gone wrong?
The second parameter is considered as props, but it is expected to be an object. you would pass it like
handleNewUserMessage = (newMessage) => {
renderCustomComponent(Reply, {correct: this.correct});
}
I would really appreciate if you could help me with that one. Namely, I have a parent component and it gets new data from a child component. In child component array-data is mapped so incoming data into parent component is not one but multiple. I would like to save it inside the list tags to get as many list items as incoming values from child component.
Here's the code:
import React, { Component } from 'react';
import TextEnter from './TextEnter.jsx';
class Terminal extends Component {
constructor(props) {
super(props);
this.state = {
incomingData: '',
};
}
updateParent(val) {
this.setState({
incomingData: <li> {val} </li> // here I would like to save every incoming mapped data
});
}
render() {
return (
<div className="terminal">
<TextEnter
afterCommand={this.props.afterCommand}
triggerParent={(val) => this.updateParent(val)}
/>
<ul className="listContainer">
{this.state.incomingData}
</ul>
</div>
);
}
}
export default Terminal;
I don't really like to store React Elements (created with <li> in a jsx file) as state. I'd rather store the list, and leave how it is rendered to the render() function. I would change it to something like:
import React, { Component } from 'react';
import TextEnter from './TextEnter.jsx';
class Terminal extends Component {
constructor(props) {
super(props);
this.state = {
incomingData: [],
};
}
updateParent(val) {
this.setState({
incomingData: this.state.incomingData.concat(val)
});
}
render() {
const listItems = this.state.incomingData.map(item => {
return <li>{ item }</li>
});
return (
<div className="terminal">
<TextEnter
afterCommand={this.props.afterCommand}
triggerParent={this.updateParent}
/>
<ul className="listContainer">
{listItems}
</ul>
</div>
);
}
}
export default Terminal;
Notice that I also pass this.updateParent directly instead of wrapping it in an anonymous function which should give the same result. You'll get a key warning from react, but I don't know what unique identifier you have access to.
I am trying to set a video in my app as "Featured" when a user clicks on an item. I have an action creator that does a simple console.log() when called, and for testing I call it w/ componentDidMount(), and it works fine. I have a separate component for the VideoItem, and I'm trying to pass down the action creator, but I get an error: TypeError: Cannot read property 'props' of undefined. I tried to add .bind(this) to the end of the action I was passing down, but it didn't make a difference.
If the action creator works when I call it at componentDidMount, why can't I pass it to the child component? Here's my Video and VideoItem component:
// Video.js
import React, { Component } from 'react'
import VideoItem from './VideoItem'
class Videos extends Component {
componentDidMount() {
this.props.actions.getVideos()
// This function works, but getting error
// when passing to VideoItem component
this.props.actions.setFeaturedVideo()
}
constructor(props) {
super(props);
}
render() {
if(this.props.videos.length == 0){
return <p>Loading....</p>
}
return (
<div className="container">
<ul className="row">
{this.props.videos.map(function(result) {
return (
<VideoItem
key={result.position}
setFeaturedVideo={this.props.setFeaturedVideo}
video={result}
/>
)
})}
</ul>
</div>
)
}
}
export default Videos
// VideoItem.js
import React, { Component } from 'react'
class VideoItem extends Component {
constructor(props) {
super(props);
}
render() {
return (
<li className="col m6" onClick={this.props.setFeaturedVideo()}>
{this.props.video.title}
</li>
)
}
}
export default VideoItem
Missed that this inside a map function. Since you are using map, the "this" belongs to the map function. You need to assign this to a variable before the map function and use that instead.
render() {
var _that = this;
if(this.props.videos.length == 0){
return <p>Loading....</p>
}
return (
<div className="container">
<ul className="row">
{this.props.videos.map(function(result) {
return (
<VideoIte
key={result.position}
setFeaturedVideo={_that.props.actions.setFeaturedVideo}
video={result}
/>
)
})}
</ul>
</div>
)
}
I noticed that to the VideoItem Component you have the code passing the function like so
<VideoItem
key={result.position}
setFeaturedVideo={this.props.setFeaturedVideo}
video={result}
/>
But in your componentDidMount you call this.props.actions.setFeatureVideo()
So to me you are not passing the function down as props since you are trying to get it from this.props instead of this.props.actions