I know we send data into child components through props, but how does one send data back up to the parent?
I have a a series of dropdown boxes where an item can be selected:
DropdownMenu.js
import React, {Component} from 'react';
export default class DropdownMenu extends Component {
constructor(props) {
super(props);
this.state = {
highlight: false,
count: this.props.count || 0,
selection: null
}
this.showDropdown = this.showDropdown.bind(this);
this.selectItem = this.selectItem.bind(this);
}
componentDidMount() {
}
showDropdown() {
}
selectItem(e) {
}
render() {
return <div className="dropdown__menu" onClick={this.props.onClick}>
{this.props.text} {this.state.count > 0 ? <b>{this.state.count}</b> : ''}
<div className="dropdown__content"
style={this.props.isOpen ? {'display': 'block'} : {'display': 'none'}}>
{this.props.children}
</div>
</div>
}
}
Which is called from CompanyList.js
constructor(props) {
super(props);
this.state = {
sortBy: null,
...
<DropdownMenu text="Sort by" isOpen={this.state.activeDropdown === "Sort_by"}
onClick={this.showDropdown.bind(this, "Sort_by")}
onMouseEnter={() => this.setState({mouseInDropdown: true})}
onMouseLeave={() => this.setState({mouseInDropdown: false})}>
<div onMouseEnter={() => this.setState({mouseInDropdown: true})}
onMouseLeave={() => this.setState({mouseInDropdown: false})}>
<li>Name</li>
<li>Age</li>
<li>Value</li>
</div>
</DropdownMenu>
...
Thanks for the replies but how do I apply the function to each of the <li> that are children of the dropdown (some dropdowns may not have any options and are just buttons)?
this.props.children
TL;DR --> https://reactjs.org/docs/faq-functions.html
Just pass a callback from the parent to the child :
// parent component
(...)
myCallback(arg1){
this.setState({val:arg1});
}
render(){
return(
<MyChildComponent onSpecificAction={this.myCallback.bind(this)} />
);
}
(...)
// child component
(...)
render(){
return(
<button onclick={(e) => this.props.onSpecificAction('value to send up')}>Button text</button>
);
}
(...)
In the same way that you are passing props to a child element, you can also pass functions.
So you can pass a function like onChange(newData) from the parent to your child component that you will call everytime the value changes.
Related
Fairly new with react. I'm creating a dropdown button for a Gatsby project. The button toggle works, but I'm having trouble getting the selected value to the parent where I need it.
-Tried lifting the state up, but this resulted in the button not appearing at all. I was a bit confused here so maybe I was doing something wrong.
-Also tried using refs although I wasn't sure if this was the right use case, it worked, however it seems the value is grabbed before it's updated in the child component and I'm not sure how to change or work around this. (the code is currently set up for this)
Are either of these options right? or could anybody steer me in the right direction, thanks.
Dropdown in parent:
this.dropdownRef1 = React.createRef();
componentDidUpdate(){
console.log("Color Option:" + this.dropdownRef1.current.state.ColorOption)
}
<DropdownBtn ref={this.dropdownRef1} mainText="Color" options={this.props.pageContext.colors || ['']} />
DropdownBtn:
export default class refineBtn extends React.Component {
constructor(props) {
super(props);
}
state = {
open: false,
[this.props.mainText + "Option"]: "all",
};
dropdownBtnToggle = () => {
this.setState((prevState)=> {
return{open: !prevState.open};
});
};
optionClickHandler = (option) => {
this.setState(() => {
console.log(this.props.mainText + " updated to " + option)
return {[this.props.mainText + "Option"] : option}
});
};
render(){
const options = this.props.options
console.log("open: " + this.state.open)
return(
<div>
<button onClick={this.dropdownBtnToggle} >
{this.props.mainText}:
</button>
<div className={this.state.open ? 'option open' : "option"} >
<p key={"all"} onClick={() => this.optionClickHandler("all")}> all</p>
{options.map(option => (
<p key={option} onClick={() => this.optionClickHandler(option)}>{option}</p>
))}
</div>
</div>
);
}
}
You can respond to selection by allowing your component to accept a callback.
class MyComponent extends React.Component {
constructor(props) {
super(props)
this.state = {open: false, value: ''}
}
render() {
return (
<div>
<div onClick={() => this.setState({open: true})}>{this.state.value}</div>
<div style={{display: this.state.open ? 'block' : 'none'}}>
{this.props.options.map((option) => {
const handleClick = () => {
this.setState({open: false, value: option})
this.props.onChange(option)
}
return (
<div key={option} onClick={handleClick} className={this.state.value === option ? 'active' : undefined}>{option}</div>
)
})}
</div>
</div>
)
}
}
<MyComponent onChange={console.log} options={...}/>
I have an accordion in React formed of a row component which is looped inside a body parent component. In the row I'm toggling the state showDetails to show/hide the details for each row, effectively opening the accordion item. But, since the state is for each row, how do I close one accordion item when I open another one?
Body:
export default class Body extends React.Component {
render() {
const {modelProps, showInfo, linkedRow} = this.props;
return (
<div className="c-table__body">
{this.props.model.map(
(subModel, i) =>
linkedRow ?
<LinkedRow
key={`${i}`}
model={subModel}
modelProps={modelProps}
/>
:
<Row
key={`${i}_${subModel.username}`}
model={subModel}
modelProps={modelProps}
showInfo={showInfo}
handleStatusChanged={this.props.handleStatusChanged}
/>
)}
</div>
);
}
}
Row:
class Row extends React.Component {
constructor(props) {
super(props);
this.state = {
userId: '',
showDetails: false,
showModal: false,
status: '',
value: '',
showInfo: false
};
render() {
const { model, modelProps, showInfo } = this.props;
return (
<div className="c-table__row">
<div className="c-table__row-wrapper">
{modelProps.map((p, i) => (
<div className={`c-table__item ${this.isStatusCell(model[p]) ? model[p] : p}`} key={i}>{this.isStatusCell(model[p]) ? this.toTitleCase(model[p]) : model[p]}</div>
))}
{showInfo ? (
<div className="c-table__item c-table__item-sm">
<a
name="view-user"
onClick={this.showDetailsPanel}
className={this.state.showDetails ? 'info showing' : 'info'}
>
<Icon yicon="Expand_Cross_30_by_30" />
</a>
</div>
) : (
''
)}
</div>
{this.state.showDetails ? (<ConnectedDetails user={model} statusToggle={this.handleStatusChange}/>) : null}
</div>
);
}
}
export default Row;
Not really sure how to approach this, maybe something in the body that check is there's any row open according to the showDetails state in the rows?
Thanks in advance
The approach is to lift the state of which <Row /> is open to the <Body /> component.
Also the method that switch between opened <Row /> is on the <Body /> component.
toggleOpen = (idx) => {
this.setState({ openRowIndex: idx });
}
then when you rendered your <Row />s you can pass a prop isOpen:
<Row
key={`${i}_${subModel.username}`}
model={subModel}
modelProps={modelProps}
showInfo={showInfo}
handleStatusChanged={this.props.handleStatusChanged}
isOpen={this.state.openRowIndex === i}
onToggle={_ => this.toggleOpen(i)}
/>
I am trying to make a custom dropdown but with custom children component. Within the children custom component, there's an onChange event.
The problem now is whenever I trigger the onChange which is for the checkbox, the dropdown is closed.
https://codesandbox.io/s/lr677jv7l7
Partial code
render() {
const { className, onOpen, children } = this.props
const { openItems, selectedItem } = this.state
return (
<div className={classnames('customDropdown', className)}>
<div tabIndex="1"
onBlur={() => { this.setState({ openItems: false }) }}
onFocus={() => { this.setState({ openItems: true }); onOpen && onOpen() }}>
<button className="btn">
{selectedItem}
</button>
<div className={classnames('items', { 'show': openItems === true, 'hide': openItems === false })}>
{children && children}
</div>
</div>
</div>
)
}
You need to get rid of following line:
onBlur={() => { this.setState({ openItems: false }) }}
It basically says that when your div wrapping the button loses focus (eg when you click the checkbox) it should set the state.openItems variable to false and therefore it closes the dropdown.
Edit:
Check out working example here: https://codesandbox.io/s/jnq2rqwr53.
Basically use onClick instead of blur and then you add click event to your document, so anytime user clicks anywhere on the document it calls your hide method and closes the modal. This way the selected checkbox gets checked, but if you want to dropdown to stay open after the selection you'll need to somehow tell the hide function not to execute if user clicked on the checkbox. I did it using ids and simple condition guard at the beginning of the hide method.
Code looks like this:
Hello.js
import React, { Component } from 'react';
import classnames from 'classnames'
export default class CustomDropdown extends Component {
constructor() {
super()
this.state = {
openItems: false,
selectedItem: 'Please select'
}
this.show = this.show.bind(this);
this.hide = this.hide.bind(this);
}
show() {
this.setState({openItems: true});
document.addEventListener("click", this.hide);
}
hide(e) {
if (e.target.id === "1" || e.target.id === "2") {
return false;
}
this.setState({openItems: false});
document.removeEventListener("click", this.hide);
}
render() {
const { className, onOpen, children } = this.props
const { openItems, selectedItem } = this.state
return (
<div className={classnames('customDropdown', className)}>
<div tabIndex="1">
<button className="btn" onClick={this.show}>
{selectedItem}
</button>
<div className={classnames('items', { 'show': openItems === true, 'hide': openItems === false })}>
{children && children}
</div>
</div>
</div>
)
}
}
index.js
import React, { Component } from 'react';
import { render } from 'react-dom';
import Hello from './Hello';
import './styles.css';
const styles = {
fontFamily: 'sans-serif',
textAlign: 'center'
};
class App extends Component {
constructor() {
super()
}
changeCheckbox = () => {
console.log('something')
}
render(){
return(
<div style={ styles }>
<Hello>
<div>
my checkbox 1
<input type="checkbox" onChange={this.changeCheckbox} id="1" />
</div>
<div>
my checkbox 2
<input type="checkbox" onChange={this.changeCheckbox} id="2" />
</div>
</Hello>
</div>
)
}
}
render(<App />, document.getElementById('root'));
I'm new to ReactJS and trying to make a small web application.
I have a list of items to put in a sidebar, and I want each item to give back a status tu the sidebar when clicked (so that I can style the active link accordingly).
import React, {Component} from 'react';
import SideBarItem from "./SideBarItem";
const items = {
'DASHBOARD' : 'home',
'Utenti': 'user',
'Corsi' : 'education',
'Logistica' : 'check',
'Comunicazioni': 'bullhorn'
};
const listItems = Object.entries(items).map(([key,value])=>{
return <SideBarItem
onClick={this.changeState(key)} active={this.state.active == key ? 'active' : ''}
title={key}
glyph={'glyphicon glyphicon-' + value.toString()}/>
});
class SideBar extends Component {
constructor(props) {
super(props);
this.state = {active: 'DASHBOARD'};
}
changeState (row) {
this.setState({
active: row
});
}
render() {
return (
<div id = "sidebar" className="col-sm-3 col-md-2 sidebar paper-depth-1">
<ul className = 'nav nav-sidebar'>
{listItems}
</ul>
</div>
);
}
}
export default SideBar;
But this code is returnig the following error:
TypeError: _this.changeState is not a function
I understand that there's something wrong in calling a component function from an outside variable, but I don't get how can I make this work in any other way.
If you create the list of items in render(), the this scope will be the component instance, as you need it to be.
class SideBar extends Component {
constructor(props) {
super(props);
this.state = {active: 'DASHBOARD'};
}
changeState(row) {
this.setState({
active: row
});
}
render() {
return (
<div id="sidebar" className="col-sm-3 col-md-2 sidebar paper-depth-1">
<ul className="nav nav-sidebar">
{Object.entries(items).map(([key,value]) =>
<SideBarItem
onClick={() => this.changeState(key)}
active={this.state.active == key ? 'active' : ''}
title={key}
glyph={'glyphicon glyphicon-' + value.toString()}
/>
)}
</ul>
</div>
);
}
}
Below is my code...
<ul className="no-style board__list">
{Object.keys(today.books).map(function(id) {
var refBook = today.books[id][0];
return (
<li key={refBook._id} className="board__list-item">
<div className="container flexrow">
<div className="flexrow__fit-2">{refBook.book_no}</div>
<div className="flexrow__org">
<span className="board__icon-wrap">
{refBook.memo
? (<i className="fa fa-flag" style={{color:"#F9AB9F"}}></i>)
: null
}
</span>
{refBooking.memo
? (<div className="memo_dialog">{refBook.memo}</div>)
: null
}
</div>
</div>
</li>
);
})}
</ul>
I have a object books array and I create a fa-flag icon for each book.
What I want is to show different memo dialog when mouse hover on each flag icon.
I know how to do it with query but how can I do this in react way not using jquery?
I'm not sure what are you trying to achieve but this example might be useful for you
class Book extends React.Component {
constructor(props){
super(props);
this.handleOver = this.handleOver.bind(this);
}
handleOver(name){
this.props.over(this.props.name)
}
render(){
return <div onMouseOver={this.handleOver}>{this.props.name}</div>
}
}
class BookList extends React.Component {
constructor(props){
super(props);
this.mouseOver = this.mouseOver.bind(this);
this.state = {
books: ['hello', 'amazing', 'world'],
memo: ''
}
}
mouseOver(name){
this.setState({memo: name})
}
render(){
const bookList = this.state.books.map((book, index)=>{
return <Book key={index} name={book} over={this.mouseOver}/>
});
return <div>
{bookList}
<hr/>
<div>{this.state.memo}</div>
</div>
}
}
React.render(<BookList />, document.getElementById('container'));
Also fiddle example.
I hope it will help you. Thanks
I suggest you to use isHovered state variable, to store hover state.
We are displaying some component(in your case it would be dialog box), if isHovered is true and hide it when this variable is false.
When we will hover on link element, we will trigger handleEnter function to set isHovered variable to true.
Similarly, when we are moving cursor out of link element, we are triggering handleLeave function to set isHovered variable to false.
Example:
class Test extends React.Component {
constructor(props) {
super(props);
this.state = {
isHovered: false,
};
}
handleEnter() {
this.setState({
isHovered: true
});
}
handleLeave() {
this.setState({
isHovered: false
});
}
render() {
return (
<div>
<a
onMouseEnter={this.handleEnter.bind(this)}
onMouseLeave={this.handleLeave.bind(this)}
>Link</a>
{this.state.isHovered ? (
<div className="box">A component</div>
) : (
<div />
)}
</div>
);
}
}
Also, you can see demo at CodePen.