Is it possible to pass the data from the child component to the parent component using props?
-Parent component
--- ItemList component.
--- DisplatSelect component from the itemList component
I have a list of item in the child component which came from to the parent component, then I want to send the index of the selected data to the other child component located in the parent component.
Can't example well, kindly see the attached screenshot for other references.
Thanks a lot!
enter image description here
You can keep the data in the Parent component and use a function to pass the props from the child to the Parent. This concept is called Lifting State Up where you define the state at the highest common ancestor so all the child components are using the same data which in this case is the selecetd item
function Parent() {
const [selectedItem, setSelectedItem] = useState(null);
const data = []; // Your Data
return (
<>
<h1>Your selected Item = {selectedItem}</h1>
{data.map((item) => {
<Child item={item} setSelectedItem={setSelectedItem} />;
})}
</>
);
}
function Child({ item, setSelectedItem }) {
return <Button onClick={() => setSelectedItem(item.id)}> {item} </Button>;
}
The simplest way, I think, is for the child component where the selection is made to accept a function properly, something like onSelectionChanged. If you had a button for each item passed to the child you could do something like:
Child Component A
const ChildA = ({ items, onSelectionChanged }) => {
return (
<div>
{items.map((item, index) => (
<button onClick={() => onSelectionChanged(index)}>Item</button>
))}
</div>
)
}
Child Component B
const ChildB = ({ selectedItem }) => {
return (
<div>
Selected {selectedItem}
</div>
)
}
Parent Component
const Parent = () => {
const [selection, sets election] = useState({});
const onSelectionChanged = index => {
console.log(`ChildA selection changed: ${index}`);
}
return (
<div>
<ChildA items={items} onSelectionChanged={onSelectionChanged} />
<ChildB selectedItem={selection} />
</div>
)
}
So when your child component handles a change in the selection, it invokes the function passed as a prop onSelectionChanged. You can pass whatever data you want from ChildA to that function.
Note that the parent Component keeps the selected value (from ChildA) in local state, then passes that value to ChildB via a prop.
You can have a state variable in the parent component and pass it to child components to share data between them. I'll post a sample code block on how you can do this for your case.
export default function ParentComponent (props) {
const data = ['image_1_url', 'image_2_url', ...] // Data for the images
const [selectedIndex, setSelectedIndex] = useState(-1); // Selected index (-1 represents no selection)
return (
<ImageList data={data} selectImage={setSelectedIndex} />
{(selectedIndex !== -1) ? (<SelectedImage data={data[selectedIndex]} />) : (<No ImageSelected/>)}
);
}
And the image list component can then use the selectImage prop to select the image
export default function ImageList (props) {
return (
<div>
props.data.map((imageUrl, index) => (
<div onClick={() => {props.setSelected(index)}}>
<img src={imageUrl}/>
</div>
))
</div>
);
}
Yes it's possible. We have one parent state value and update every on click child component to the component.
import React, { useState } from "react";
const Child1 = (props) => {
return (
props.items.map( (item, index) => (
<button key={index.toString()} onClick={() => { props.updateIndex(item.id) }}>
{item.name}
</button>
) )
)
}
const Child2 = (props) => {
return (
<h1>Item selected: {props.selectItem}</h1>
)
}
const ParentComponent = () => {
const listItems = [
{
id:1,
name: "sample name 1"
},
{
id:2,
name: "sample name 2"
}
]
const [selectItem, setSelectItem] = useState('None');
return (
<>
<Child1 items={listItems} updateIndex={setSelectItem}/>
<Child2 selectItem={selectItem}/>
</>
)
}
export default function App() {
return (
<div className="App">
<ParentComponent/>
</div>
);
}
Related
I m having one sub child component which is inside a loop of parent component. when one of the sub child components is updating the state of parent component, it is re-rendering the all children since it is loop. How can i avoid the re-render for each iteration. It should update that particular sub child.
import React, { useState } from "react";
function Parent() {
const [selectedChild, setSelectedChild] = useState([]);
const onChangeHandle = (event, id) => {
const checked = event.target.checked;
let updatedArray = [...selectedChild];
if (checked) {
if (!selectedChild.includes(id)) {
updatedArray.push(id);
}
} else {
var index = updatedArray.indexOf(id);
if (index !== -1) {
updatedArray.splice(index, 1);
}
}
setSelectedChild(updatedArray);
};
return (
<div>
<table>
<tbody>
{[1, 2, 3].map((value, index) => {
return (
<Child
key={index}
index={index}
value={value}
handle={onChangeHandle}
isSelected={selectedChild.includes(index)}
/>
);
})}
</tbody>
</table>
<div>{selectedChild}</div>
</div>
);
}
function Child({ index, value, handle, isSelected }) {
console.log("rendering child");
return (
<tr>
<td>
<SubChild
isChecked={isSelected}
onChangeHandle={handle}
index={index}
/>
</td>
<td>
hello {index} {value}
</td>
</tr>
);
}
function SubChild({ isChecked, onChangeHandle, index }) {
console.log("rendering subchild");
return (
<input
type="checkbox"
checked={isChecked}
onChange={(event) => onChangeHandle(event, index)}
/>
);
}
export default function App() {
return (
<div className="App">
<Parent />
</div>
);
}
Current behaviour: In above code, When i m clicking on the checkbox(which is Sub child) in one of the children component, it is updating the parent component state(selectedChild). So the loop is executing and all children(all table rows) are re rendering.
Expected behaviour: Only that particular sub child have to go for re-render (even it should not re-render child)
Demo: https://codesandbox.io/s/reactqa2-0c0md?file=/src/App.js
Little related question: How to avoid rerender all child components which in loop when parent component state update
You should use memoization (useCallback/React.memo) and rewrite handle logic with functional updates.
Also, you avoid Child to render, since you have a new value after rendering.
// Make a stable callback
const onChangeHandle = useCallback((event, id) => {
setSelectedChild((updatedArray) => {
if (event.target.checked) {
if (!updatedArray.includes(id)) {
return [...updatedArray, id];
}
} else {
return updatedArray.filter((currId) => currId !== id);
}
return updatedArray;
});
}, []);
// Memoize the component
const MemoChild = React.memo(Child);
const MemoSubChild = React.memo(SubChild);
I have a parent and a child component, child component has a button, which I'd like to disable it after the first click. This answer works for me in child component. However the function executed on click now exists in parent component, how could I pass the attribute down to the child component? I tried the following and it didn't work.
Parent:
const Home = () => {
let btnRef = useRef();
const handleBtnClick = () => {
if (btnRef.current) {
btnRef.current.setAttribute("disabled", "disabled");
}
}
return (
<>
<Card btnRef={btnRef} handleBtnClick={handleBtnClick} />
</>
)
}
Child:
const Card = ({btnRef, handleBtnClick}) => {
return (
<div>
<button ref={btnRef} onClick={handleBtnClick}>Click me</button>
</div>
)
}
In general, refs should be used only as a last resort in React. React is declarative by nature, so instead of the parent "making" the child disabled (which is what you are doing with the ref) it should just "say" that the child should be disabled (example below):
const Home = () => {
const [isButtonDisabled, setIsButtonDisabled] = useState(false)
const handleButtonClick = () => {
setIsButtonDisabled(true)
}
return (
<>
<Card isDisabled={isButtonDisabled} onButtonClick={handleButtonClick} />
</>
)
}
const Card = ({isDisabled, onButtonClick}) => {
return (
<div>
<button disabled={isDisabled} onClick={onButtonClick}>Click me</button>
</div>
)
}
Actually it works if you fix the typo in prop of Card component. Just rename hadnlBtnClick to handleBtnClick
You don't need to mention each prop/attribute by name as you can use javascript Object Destructuring here.
const Home = () => {
const [isButtonDisabled, setIsButtonDisabled] = useState(false)
const handleButtonClick = () => {
setIsButtonDisabled(true)
}
return (
<>
<Card isDisabled={isButtonDisabled} onButtonClick={handleButtonClick} />
</>
)
}
const Card = (props) => {
return (
<div>
<button {...props}>Click me</button>
</div>
)
}
You can also select a few props and use them differently in the child components. for example, see the text prop below.
const Home = () => {
const [isButtonDisabled, setIsButtonDisabled] = useState(false)
const handleButtonClick = () => {
setIsButtonDisabled(true)
}
return (
<>
<Card text="I'm a Card" isDisabled={isButtonDisabled} onButtonClick={handleButtonClick} />
</>
)
}
const Card = ({text, ...restProps}) => {
return (
<div>
<button {...restProps}>{text}</button>
</div>
)
}
I have a Form and Input components, which are rendered as below.
<Form>
<Field />
<Field />
<Field />
</Form>
Form component will act as wrapper component here and Field component ref are not being set here. I want iterate through props.children in Form Component and want to assign a ref attribute to each children. Is there any possibility to achieve this?
You need Form to inject your refs with React.Children and React.cloneElement APIs:
const FunctionComponentForward = React.forwardRef((props, ref) => (
<div ref={ref}>Function Component Forward</div>
));
const Form = ({ children }) => {
const childrenRef = useRef([]);
useEffect(() => {
console.log("Form Children", childrenRef.current);
}, []);
return (
<>
{React.Children.map(children, (child, index) =>
React.cloneElement(child, {
ref: (ref) => (childrenRef.current[index] = ref)
})
)}
</>
);
};
const App = () => {
return (
<Form>
<div>Hello</div>
<FunctionComponentForward />
</Form>
);
};
You can map children create new instance of component based on it using one of two ways showed in React Docs.
With React.Children.map and React.cloneElement (this way, key and ref from original element are preserved)
Or only with React.Children.map (Only ref from original component is preserved)
function useRefs() {
const refs = useRef({});
const register = useCallback((refName) => ref => {
refs.current[refName] = ref;
}, []);
return [refs, register];
}
function WithoutCloneComponent({children, ...props}) {
const [refs, register] = useRefs();
return (
<Parent>
{React.Children.map((Child, index) => (
<Child.type
{...Child.props}
ref={register(`${field-${index}}`)}
/>
)}
</Parent>
)
}
function WithCloneComponent({children, ...props}) {
const [refs, register] = useRefs();
return (
<Parent>
{
React.Children.map((child, index) => React.cloneElement(
child,
{ ...child.props, ref: register(`field-${index}`) }
)
}
</Parent>
)
}
I have a page called: List.js which renders the component: Box for every item on the List page. My List.js also consists of a component called: MainSpace. Now every Box component will consists of a button with an onClick function. Depending on which Box component you click, I want to fill the MainSpace with data coming from that specific Box component, but I can't seem to figure out how to do this.
render() {
for (let index in data) {
list.push(
<Box data={data[index]}/>
);
}
return (
<div>
{list}
<MainSpace>
</div>
);
}
Now the Box component looks something like this:
class Box extends Component {
fillMainSpace(){
//Send this.prop.data to the list.js file and fill the MainSpace component from there I think?
}
render(){
return (
<div>
<span>{this.props.data.text}</span>
<button onClick={this.fillMainSpace}></button>
</div>
);
}
}
Mainspace doesn't have much. I just want to load for example the this.props.data.image from the clicked button from the Box component. Even console.log(this.props.data); would be sufficient. Calling the <MainSpace> component in every <Box> component is not an option, since that would render a lot of unnecessary extra components.
So my question being:
How would I be able to access the this.props.data of the clicked button of a <Box> component and use it in my <MainSpace> component?
EDIT:
Adding the MainSpace Component:
class MainSpace extends Component {
render(){
return (
<div>
{this.props.data.image}
</div>
);
}
}
You can save selected item in state like selectedItem and then pass that data to MainSpace
const List = props => {
const [selectedItem, setSelectedItem] = useState(props.data[0]);
const onSelect = item => {
setSelectedItem(item);
};
return (
<div calssName="list">
{props.data.map(item => <Box data={item} onSelect={onSelect} />)}
<MainSpace data={selectedItem} />
}
}
const Box = props => {
const { data, onSelect } = props;
return (
<div>
<span>{data.someKey}</span>
<button onClick={() => onSelect(data)} >Select</button>
</div>
);
};
Using class components
class Box extends Component {
fillMainSpace = () => {
const { onSelect, data } = this.props;
onSelect(data);
}
render(){
const { data } = this.props;
return (
<div>
<span>{data.text}</span>
<button onClick={this.fillMainSpace} }></button>
</div>
);
}
}
class List extends React.Component {
state = { selectedItem: this.props.data[0] };
onSelect = item => {
this.setState({ selectedItem: item });
}
render() {
const { data } = this.props;
const { selectedItem } = this.state;
const list = data.map(item => <Box data={item} onSelect={this.onSelect} />);
return (
<div>
{list}
<MainSpace data={selectedItem}>
</div>
);
}
}
I'm generating some identical div through a list. Below is the sample code.
I'm toggling this div
class App extends React.Component {
state = { showKitten: false };
handleToggleKitten = () => {
this.setState((prevState, props) => ({
showKitten: !prevState.showKitten,
}));
};
render() {
return (
<About
data={datalist}
showKitten={this.state.showKitten}
handleToggleKitten={this.handleToggleKitten}
/>
);
}
}
const About = ({ datalist, showKitten, handletogglekitten }) => {
return (
<div>
{datalist.map((item, index) => {
return (
<div key={index}>
<div onClick={handletogglekitten} />
showKitten ? <div /> : null
</div>
);
})}
</div>
);
};
I have defined tooglefunction and the flag state variable in parent and passing them to children and in children component, I'm creating this divs by iterating over a list. Right now I am able to achieve the toggle functionality for the individual div set but I want to hide all the div and show the one which is clicked.
You could use the index value. Here's a working example.
const datalist = ["cat 1", "cat 2", "cat 3"];
class App extends React.Component {
state = { showKittenIndex: null };
render() {
return (
<About
datalist={datalist}
showKittenIndex={this.state.showKittenIndex}
toggleKitten={index => this.setState({ showKittenIndex: index })}
/>
);
}
}
const About = ({ datalist, showKittenIndex, toggleKitten }) => (
<div className="about">
{datalist.map((item, index) => (
<div key={index}>
<button onClick={() => toggleKitten(index)}>toggle {index}</button>
{showKittenIndex === index && <div>{item}</div>}
</div>
))}
</div>
);
I have a very similar approach than #Kunukn.
But I don't see the need to wrap it in a functional component.
import React, { Component } from 'react';
const elements = ['DIV #1', 'DIV #2', 'DIV #3', 'DIV #4', 'DIV #5', 'DIV #6'];
class App extends Component {
constructor(props) {
super(props);
this.state = {
activeElement: null,
allElements: elements,
};
}
render() {
return (
<About
elements={this.state.allElements}
showIndex={this.state.activeElement}
toggleIndex={index => this.setState({ activeElement: index })}
/>
);
}
}
const About = ({ elements, showIndex, toggleIndex }) => (
<div className="about">
{elements.map((element, index) => (
<div key={index}>
<div onClick={() => toggleIndex(index)}>toggleIndex {index}</div>
{showIndex === index && <div>{element}</div>}
</div>
))}
</div>
);
export default App;
I did write a little clickHandler ... I know that it is not needed at the moment, but when you would want to alter the data received with the click-event this could be handled there as well.
EDIT
According to the comment I improved the code a bit by making a functional component showing the DIVs. I did also dismiss the clickHandler() function.