javascript - 如何将 redux 状态传递给子路由？

Question

我很难理解如何将 redux 与 react-router 一起使用。

索引.js

[...]

// Map Redux state to component props
function mapStateToProps(state)  {
  return {
    cards: state.cards
  };
}

// Connected Component:
let ReduxApp = connect(mapStateToProps)(App);

const routes = <Route component={ReduxApp}>
  <Route path="/" component={Start}></Route>
  <Route path="/show" component={Show}></Route>
</Route>;

ReactDOM.render(
  <Provider store={store}>
    <Router>{routes}</Router>
  </Provider>,
  document.getElementById('root')
);

App.js

import React, { Component } from 'react';

export default class App extends React.Component {
  render() {
    const { children } = this.props;
    return (
      <div>
      Wrapper
        {children}
      </div>
    );
  }
}

显示.js

import React, { Component } from 'react';

export default class Show extends React.Component {
  constructor(props) {
    super(props);
  }

  render() {
    return (
      <ul>
        {this.props.cards.map(card => 
          <li>{card}</li>
        )}
      </ul>
    );
  }
}

这抛出

Uncaught TypeError: Cannot read property 'map' of undefined

我找到的唯一解决方案是使用它而不是 {children}:

{this.props.children &&
 React.cloneElement(this.props.children, { ...this.props })}

这真的是正确的做法吗？

Answer 1

使用 react-redux

为了将任何状态或 Action 创建者注入(inject)到 React 组件的 props 中，您可以使用来自 react-redux 的 connect这是 Redux 的官方 React 绑定(bind)。​​

值得查看connect 的文档here .

作为一个基于问题中指定内容的示例，您将执行如下操作:

import React, { Component } from 'react';
// import required function from react-redux
import { connect } from 'react-redux';

// do not export this class yet
class Show extends React.Component {
  // no need to define constructor as it does nothing different from super class

  render() {
    return (
      <ul>
        {this.props.cards.map(card => 
          <li>{card}</li>
        )}
      </ul>
    );
  }
}

// export connect-ed Show Component and inject state.cards into its props.
export default connect(state => ({ cards: state.cards }))(Show);

尽管您必须使用 react-redux 中的 Provider 包装您的根组件或路由器，但为了使其正常工作(这已经存在于您上面的示例中).但为了清楚起见:

import React from 'react';
import ReactDOM from 'react-dom';
import { Router, Route } from 'react-router';

import { createStore } from 'redux';
import { Provider } from 'react-redux';

import reducers from './some/path/to/reducers';

const store = createStore(reducers);

const routes = <Route component={ReduxApp}>
  <Route path="/" component={Start}></Route>
  <Route path="/show" component={Show}></Route>
</Route>;

ReactDOM.render(
  // Either wrap your routing, or your root component with the Provider so that calls to connect have access to your application's state
  <Provider store={store}>
    <Router>{routes}</Router>
  </Provider>,
  document.getElementById('root')
);

如果任何组件不需要注入(inject)任何状态或 Action 创建者，那么您可以只导出一个“愚蠢”的 React 组件，并且您的应用程序的任何状态都不会在呈现时暴露给该组件。