我的结构如下所示:
Component 1
- |- Component 2
- - |- Component 4
- - - |- Component 5
Component 3
组件3应该根据组件5的状态显示一些数据。
因为道具是不可变的,我不能简单地在组件1中保存它的状态并转发它,对吗?是的,我读过Redux,但我不想使用它。我希望只用react就能解决这个问题。我错了吗?
我的结构如下所示:
Component 1
- |- Component 2
- - |- Component 4
- - - |- Component 5
Component 3
组件3应该根据组件5的状态显示一些数据。
因为道具是不可变的,我不能简单地在组件1中保存它的状态并转发它,对吗?是的,我读过Redux,但我不想使用它。我希望只用react就能解决这个问题。我错了吗?
当前回答
似乎我们只能将数据从父组件传递给子组件,因为React促进单向数据流,但为了让父组件在“子组件”中发生某些事情时更新自己,我们通常使用所谓的“回调函数”。
我们将父类中定义的函数作为“props”传递给子类 从子进程调用该函数,在父进程中触发它 组件。
class Parent extends React.Component {
handler = (Value_Passed_From_SubChild) => {
console.log("Parent got triggered when a grandchild button was clicked");
console.log("Parent->Child->SubChild");
console.log(Value_Passed_From_SubChild);
}
render() {
return <Child handler = {this.handler} />
}
}
class Child extends React.Component {
render() {
return <SubChild handler = {this.props.handler}/ >
}
}
class SubChild extends React.Component {
constructor(props){
super(props);
this.state = {
somethingImp : [1,2,3,4]
}
}
render() {
return <button onClick = {this.props.handler(this.state.somethingImp)}>Clickme<button/>
}
}
React.render(<Parent />,document.getElementById('app'));
HTML
----
<div id="app"></div>
在这个例子中,我们可以通过将函数传递给它的直接子函数来实现数据从子→子→父的传递。
其他回答
我们可以通过将一个函数作为props传递给子组件来设置子组件的父状态,如下所示:
class Parent extends React.Component{
state = { term : ''}
onInputChange = (event) => {
this.setState({term: event.target.value});
}
onFormSubmit = (event) => {
event.preventDefault();
this.props.onFormSubmit(this.state.term);
}
render(){
return (
<Child onInputChange={this.onInputChange} onFormSubmit=
{this.onFormSubmit} />
)
}
}
class Child extends React.Component{
render(){
return (
<div className="search-bar ui segment">
<form className="ui form" onSubmit={this.props.onFormSubmit}>
<div class="field">
<label>Search Video</label>
<input type="text" value={this.state.term} onChange=
{this.props.onInputChange} />
</div>
</form>
</div>
)
}
}
这样,子进程将更新父进程的状态onInputChange和onFormSubmit是父进程传递的道具。这可以从子进程中的事件侦听器调用,因此状态将在那里更新。
我喜欢关于传递函数的答案。这是一个非常方便的技巧。
On the flip side you can also achieve this using pub/sub or using a variant, a dispatcher, as Flux does. The theory is super simple. Have component 5 dispatch a message which component 3 is listening for. Component 3 then updates its state which triggers the re-render. This requires stateful components, which, depending on your viewpoint, may or may not be an anti-pattern. I'm against them personally and would rather that something else is listening for dispatches and changes state from the very top-down (Redux does this, but it adds additional terminology).
import { Dispatcher } from 'flux'
import { Component } from 'React'
const dispatcher = new Dispatcher()
// Component 3
// Some methods, such as constructor, omitted for brevity
class StatefulParent extends Component {
state = {
text: 'foo'
}
componentDidMount() {
dispatcher.register( dispatch => {
if ( dispatch.type === 'change' ) {
this.setState({ text: 'bar' })
}
}
}
render() {
return <h1>{ this.state.text }</h1>
}
}
// Click handler
const onClick = event => {
dispatcher.dispatch({
type: 'change'
})
}
// Component 5 in your example
const StatelessChild = props => {
return <button onClick={ onClick }>Click me</button>
}
使用Flux的调度程序捆绑非常简单。它只是简单地注册回调,并在任何分派发生时调用它们,传递分派上的内容(在上面的简洁示例中,分派没有有效负载,只有一个消息id)。如果对您更有意义的话,您可以很容易地将其调整为传统的pub/sub(例如,从事件中使用EventEmitter或其他版本)。
这似乎对我有用
家长:
...
const [open, setOpen] = React.useState(false);
const handleDrawerClose = () => {
setOpen(false);
};
...
return (
<PrimaryNavigationAccordion
handleDrawerClose={handleDrawerClose}
/>
);
孩子:
...
export default function PrimaryNavigationAccordion({
props,
handleDrawerClose,
})
...
<Link
to={menuItem.url}
component={RouterLink}
color="inherit"
underline="hover"
onClick={() => handleDrawerClose()}
>
{menuItem.label}
</Link>
我想感谢得到最多赞的回答,因为他给了我自己的问题的想法,基本上是用箭头函数和从子组件传递参数的变化:
class Parent extends React.Component {
constructor(props) {
super(props)
// without bind, replaced by arrow func below
}
handler = (val) => {
this.setState({
someVar: val
})
}
render() {
return <Child handler = {this.handler} />
}
}
class Child extends React.Component {
render() {
return <Button onClick = {() => this.props.handler('the passing value')}/ >
}
}
希望它能帮助到别人。
这是如何使用新的useState钩子。
方法-将状态改变器函数作为道具传递给子组件,并对该函数做任何你想做的事情:
import React, {useState} from 'react';
const ParentComponent = () => {
const[state, setState]=useState('');
return(
<ChildComponent stateChanger={setState} />
)
}
const ChildComponent = ({stateChanger, ...rest}) => {
return(
<button onClick={() => stateChanger('New data')}></button>
)
}