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

父组件

 function Parent() {
        const [value, setValue] = React.useState("");

        function handleChange(newValue) {
          setValue(newValue);
        }

        // We pass a callback to Child
        return <Child value={value} onChange={handleChange} />;
    }

子组件

    function Child(props) {
         function handleChange(event) {
             // Here, we invoke the callback with the new value
             props.onChange(event.target.value);
         }
  
         return <input value={props.value} onChange={handleChange} />
    }

其他回答

我找到了以下工作解决方案,将onClick函数参数从子组件传递给带有参数的父组件:

父类:

class Parent extends React.Component {
constructor(props) {
    super(props)

    // Bind the this context to the handler function
    this.handler = this.handler.bind(this);

    // Set some state
    this.state = {
        messageShown: false
    };
}

// This method will be sent to the child component
handler(param1) {
console.log(param1);
    this.setState({
        messageShown: true
    });
}

// Render the child component and set the action property with the handler as value
render() {
    return <Child action={this.handler} />
}}

子类:

class Child extends React.Component {
render() {
    return (
        <div>
            {/* The button will execute the handler function set by the parent component */}
            <Button onClick={this.props.action.bind(this,param1)} />
        </div>
    )
} }
<Footer 
  action={()=>this.setState({showChart: true})}
/>

<footer className="row">
    <button type="button" onClick={this.props.action}>Edit</button>
  {console.log(this.props)}
</footer>

Try this example to write inline setState, it avoids creating another function.

只需通过props将父组件的setState函数传递给子组件。

function ParentComp() {
  const [searchValue, setSearchValue] = useState("");
  return <SearchBox setSearchValue={setSearchValue} searchValue={searchValue} />;
}

然后在子组件中:

function SearchBox({ searchValue, setSearchValue }) {
  return (
        <input
          id="search-post"
          type="text"
          value={searchValue}
          onChange={(e) => setSearchValue(e.target.value)}
          placeholder="Search Blogs ..."
        />
    )
}

处理子组件点击的第二个例子:

// We've below function and component in parent component
const clickHandler = (val) => {
  alert(`httpRequest sent. \nValue Received: ${val}`);
};

// JSX
<HttpRequest clickHandler={clickHandler} />

这就是你如何从父组件中获取函数,然后传递一个值并通过它触发clickHandler。

function HttpRequest({ clickHandler }) {
  const [content, setContent] = useState("initialState");

  return (
    <button onClick={() => clickHandler(content)}>
      Send Request
    </button>
  );
}

export default HttpRequest;

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>

下面是获得两种绑定数据方式的简短代码片段。

计数器显示来自父进程的值,并从子进程更新

class Parent extends React.Component { constructor(props) { super(props) this.handler = this.handler.bind(this) this.state = { count: 0 } } handler() { this.setState({ count: this.state.count + 1 }) } render() { return <Child handler={this.handler} count={this.state.count} /> } } class Child extends React.Component { render() { return <button onClick={this.props.handler}>Count {this.props.count}</button> } } ReactDOM.render(<Parent />, document.getElementById("root")); <script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script> <div id="root"></div>