reactjs - 父子组件中的 MapStateToProps 和 MapDispachToProps 不起作用

Question

在我的 app.js 中，我有我的 mapDispachToProps 函数，它应该发送一个类型为:increment 的 Action 到 redux 存储中的 reducer。当 reducer 收到它时，他应该将初始状态递增 1。

在作为 app.js 组件子组件的标题组件中，我想通过 mapStateToProps 和 this.props.value 显示新值。问题是它不起作用，我在控制台中没有收到任何错误消息。

当我在 App.js 中执行所有操作时，它运行良好。

我做错了什么？

提前致谢

我的 index.js

let store = createStore(increaseReducer);

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

我的商店

export function increaseReducer(state = 0, action) {
    if(action.type == "INCREMENT") {
        return state+1;
    }   

    else {
        return state;
    }
}
export default increaseReducer;

我的 app.js

import React, {Component} from 'react';
import{ connect }from 'react-redux';
import {Heading} from './components/heading';

class App extends Component {
  constructor(props) {
    super(props);
  }
  render() {
  return (
    <div className="App">
       <Heading></Heading>
       <button onClick={this.props.increment} > Counter</button>
    </div>
  );
  }
}

let mapDispachToProps= {
  increment:()=> {
  return {type:"INCREMENT"}}
}

let AppContainer= connect(null,mapDispachToProps)(App);
export default AppContainer;

我的 heading.js

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

export class Heading extends Component {
        constructor(props){
            super(props);
        }

        render() {
            return(
                    <h1>Click Counter: {this.props.value}  </h1>    
                )
        }
}

let mapStateToProps = (state)=>{return {
  value: state
}}

let headingContainer = connect(mapStateToProps)(Heading);

export default headingContainer;

Answer 1

标题默认导出，所以在 App 中它应该是:

import Heading from './components/heading';

这是您的代码片段，它有效:

const {
  Provider,
  connect,
} = ReactRedux;
const { createStore } = Redux;
const { Component } = React;

function increaseReducer(state = 0, action) {
  if (action.type == 'INCREMENT') {
    return state + 1;
  } else {
    return state;
  }
}
let store = createStore(increaseReducer);

//heading
class HeadingComponent extends Component {
  constructor(props) {
    super(props);
  }

  render() {
    return <h1>Click Counter: {this.props.value} </h1>;
  }
}

let mapStateToProps = (state) => {
  return {
    value: state,
  };
};

let Heading = connect(mapStateToProps)(HeadingComponent);

class App extends Component {
  constructor(props) {
    super(props);
  }
  render() {
    return (
      <div className="App">
        <Heading></Heading>
        <button onClick={this.props.increment}>
          {' '}
          Counter
        </button>
      </div>
    );
  }
}

let mapDispachToProps = {
  increment: () => {
    return { type: 'INCREMENT' };
  },
};

let AppContainer = connect(null, mapDispachToProps)(App);

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

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/redux/4.0.5/redux.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-redux/7.2.0/react-redux.min.js"></script>


<div id="root"></div>