Is it possible to receive ALL props passed in a child component without explicitly specifying them one by one? Eg:
const ParentComponent = () => {
return <ChildComponent
prop1={"foo"}
prop2={"bar"}
prop3={"baz"}
/>
}
const ChildComponent = (props) => {
return <input /*GIMME ALL PROPS HERE*/ />
}
Use the spread operator for this -
const ChildComponent = (props) => {
return <input {...props} />
}
This gets automatically interpreted as -
const ChildComponent = (props) => {
return <input prop1={"foo"}
prop2={"bar"}
prop3={"baz"} />
}
Related
Problem
I have multiple Child components, which are able to pass up its state to a Parent component. I now want to be able to render multiple Parent components within a Grandparent component, and then be able to take the states of each Parent component and combine it into 1 singular state/object within the Grandparent component. Please refer to this codesandbox or look at the code below.
Child.tsx
import TextField from "#mui/material/TextField"
type Props = {
valueChange: (e: React.ChangeEvent<HTMLInputElement>) => void
id: string
}
const Child: React.FC<Props> = ({ valueChange, id }) => {
return (
<>
<TextField
id={id}
label={id}
name={id}
variant="outlined"
onChange={valueChange}
/>
</>
)
}
export default Child
Child2.tsx
import Checkbox from "#mui/material/Checkbox"
type Props = {
valueChange: (e: React.ChangeEvent<HTMLInputElement>) => void
id: string
}
const Child2: React.FC<Props> = ({ valueChange, id }) => {
return (
<>
<Checkbox name={id} onChange={valueChange} />
</>
)
}
export default Child2
Parent.tsx
import { useState } from "react"
import Child from "./Child"
import Child2 from "./Child2"
type Props = {}
const Parent: React.FC<Props> = ({}) => {
const [values, setValues] = useState({})
const valuesChange = (e: React.ChangeEvent<HTMLInputElement>) => {
const name = e.target.name
let value: any
if (name === "bool") {
value = e.target.checked
} else {
value = e.target.value
}
setValues((prev) => {
return { ...prev, [name]: value }
})
}
return (
<>
<div>{JSON.stringify({ values })}</div>
<div>
<Child valueChange={valuesChange} id={"Text1"} />
<Child valueChange={valuesChange} id={"Text2"} />
<Child2 valueChange={valuesChange} id={"bool"} />
</div>
</>
)
}
export default Parent
Grandparent.tsx
import { Button } from "#mui/material"
import Parent from "./Parent"
const Grandparent: React.FC = () => {
const buttonClick = () => {
alert(
"Want this to look like following \n" +
"data: [{Parent1 state},{Parent2 state}]"
)
}
return (
<>
<Parent />
<Parent />
<Button onClick={buttonClick}>Get Grandparent State</Button>
</>
)
}
export default Grandparent
Just move state to the highest parent (grandparent) in your case which needs them.
You can then pass what state each child component needs as props accordingly.
Thus the state in your case should be in grandpa component. It is passed to each parent as <Parent state={state.child1} /> and so on for others.
The onchange will be complex though.
I am new with React development and I wonder if this is considered an anti-pattern to pass down setState hook as props.
My code looks like this:
const App = () => {
const [value, setValue] = useState('')
return (
<Component value={value} helpers={{ setValue }} />
)
}
const Component = (props) => {
return <Component2 {...props} />
}
const Component2 = (props) => {
return <Input {...props} />
}
const Input = (props) => {
const handleChange = (e) => props.helpers.setValue(e.target.value)
return <input onChange={handleChange} {...props} />
}
I am working with React-Hook-Form and I need to declare the state at the top level but I still want my handleChange function to be at the component level. However, I don't see this pattern on example codes.
Is it an anti-pattern?
I tried the following code but it fails
So, this is my Parent Component:
import React from 'react'
import ChildComponent from './ChildComponent';
const ParentComponent = (props) => {
//step 1
// const inputRef = React.createRef();
const buttonRef = React.useRef();
const focusHandler = () => {
alert("hi");
}
return (
<div>
{/* In parent, we generally pass reference to child which we dint do here, lets see if props children help here */}
{props.children}
<ChildComponent ref="buttonRef" />
</div>
)
}
export default ParentComponent;
This is my child component:
import React from 'react'
const ChildComponent = React.forwardRef((props, ref) => {
return (
<div>
<button onClick={ref.focusHandler}>Focus Input</button>
</div>
)
})
export default ChildComponent;
On click of the button above in child component, I wish to call Parent method.
How can that be achieved?
EDITED
The reason you're getting the error is because refs in function components need to be passed using ref={buttonRef}, not ref="buttonRef". Class components have a thing they can do with string refs, but it's not recommended even there.
As for calling a function from a parent component, you don't need refs to do this. So if that was the only reason you were using a ref, you can remove the ref. Instead, pass the function as a prop:
const ParentComponent = (props) => {
const focusHandler = () => {
alert("hi");
}
return (
<div>
<ChildComponent focusHandler={focusHandler} />
</div>
)
}
const ChildComponent = (props) => {
return (
<div>
<button onClick={props.focusHandler}>Focus Input</button>
</div>
)
}
Just replace ref by focusHandler like below in parent component
<ChildComponent focusHandler={focusHandler} />
Then in ChildComponent, remove ref as well.
If you wonder how to use refs in this case (even though this is not the recommended way to pass callbacks), you need to assign focusHandler key and use the ref with ref.current, refer to Components and Props docs.
const ParentComponent = () => {
const buttonRef = React.useRef({ focusHandler: () => alert("hi") });
return (
<div>
<ChildComponent ref={buttonRef} />
</div>
);
};
const ChildComponent = React.forwardRef((props, ref) => {
return (
<div>
<button onClick={ref.current.focusHandler}>Focus Input</button>
</div>
);
});
Using Hooks, how can I pass the item.id from the child component to the parent component by clicking the button inside the child component?
The parent component:
import React from 'react'
import MyList from '../MyList'
const App = props => {
return (
<div className='App'>
<MyList />
</div>
)
}
export default App
The child component:
import React from 'react'
import jsonResponse from '../data'
function MyList (props) {
const list = jsonResponse.map((item) => {
return (
<li className='list-container' key={item.id}>
<h4>Name: {item.name}</h4>
<button className='btn'>More details</button>
</li>
)
})
return (
<ul id='container'>
{list}
</ul>
)
}
export default MyList
React is all about data flowing down in the components tree. If you want your Child to be able to show and/or modify a shared state between Child and Parent you should lift your state up and pass it down via props to it's children
const Parent = () =>{
const [title, settitle] = useState('foo')
return <Child title={title} setTitle={setTitle} />
}
const Child = ({ title, setTitle}) =>{
return <input value={title} onChange={e => setTitle(e.target.value)} />
}
In class based components
class Parent extends React.Component{
state = { title: '' }
setTitle = title => this.setState({ title })
render(){
const { title } = this.state
return <Child title={title} setTitle={this.setTitle} />
}
}
class Child extends React.Component{
render(){
const { title, setTitle } = this.props
return <input value={value} setTitle={e => setTitle(e.target.value)} />
}
}
But if you really insists that your Child holds the state (anti pattern) you can do something like this
const Parent = () =>{
const [childProp, setChildProp] = useState(null)
return <Child setChildProp={setChildProp} />
}
const Child = ({ setChildProp }) =>{
return <button onClick={() => setChildProp('foo')}>Change to foo</button>
}
Recently we got Context support in react.
Lets take next example:
<Consumer>{value => <Child value={value} />}</Consumer>
How do i make a component that sends "value" same way to its child?
I mean
<MyComponent>{value => ...}</MyComponent>
You make your component to use render props callback pattern like
class MyComponent extends React.Component {
state = {
value: 'abc'
}
render() {
return React.Children.only(this.props.children)(this.state.value)
}
}
and then you can use it like
<MyComponent>{value => ...}</MyComponent>
maybe a higher order component (HOC)?
function withContext(Component) {
return WithContext = (props) => (
<Consumer>
{
value => <Component {...props} value={value} />
}
</Consumer>
)
}
let MyComponent = ({ value }) => (
<div>
{value} // if value is something that can be rendered
</div>
)
MyComponent = withContext(MyComponent);
or with render props:
const MyComponent = (props) => (
<Consumer>
{value => props.children(value)}
</Consumer>
)
const example = (
<MyComponent>
{value => <div>{value}</div>} // children prop has to be function now
</MyComponent>
)