React-Redux 连接不工作

Question

我正在尝试在我的 codepen 笔中使用 React+Redux，但是连接没有注入 prop，

也许是因为我是业余爱好者，所以我错过了一些东西。请看一看。 http://codepen.io/sahil28v/pen/EKEKME?editors=0010

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

const Application = () =>  (
        <div className="ground">
    <Tmap />
        </div>
    );

class Tmap extends Component {
  constructor(props){
  super(props);
  console.log(this.props.mapstate);  // This is returning undefined,no idea why
  console.log(store.getState().mapstate); // Though this returns val: "hey" as it should properly though.
 }
 render () {
  return (
   <div>

   </div>
  );
 }
}

const mapStateToProps = (state) => ({
mapstate: state.mapstate
});

connect(mapStateToProps)(Tmap);

const initialState = {
  val: "hey"
}

const mapReducer = (state = initialState, action) => {
 return state ;
} ;

const rootReducer = combineReducers({
  mapstate: mapReducer,
});

const store = createStore(rootReducer);

React.render(
    <Provider store={store}>
        <Application />
    </Provider>, document.getElementById('app')
);

此外，我可以在 codepen 本身中在这里配置存储以使用 redux devtools（chrome 扩展）。我尝试添加 ...window.devToolsExtension ？ window.devToolsExtension() : f => f ，到创建商店，但这不起作用。

虽然有人在回答 -- 你也可以推荐好的 documentation/video 用于： ->学习 ES6 ...

-- 感谢帮助

Answer 1

连接 returns 我想是该组件的一个新实例。这有效，使用 connect 作为装饰器。

@connect(
  state => ({
    mapstate: state.mapstate 
  })
)
class Tmap extends Component {
  constructor(props){
    super(props);
    alert(this.props.mapstate);  // This is returning undefined,no idea why
    alert(store.getState().mapstate); //As I understand this is the direct low level api which connect is meant to abstract away along with store.subscribe.
  }

  render () {
    return (
    <div>
    </div>
    );
  }
}

Answer 2

您忘记将连接结果保存到新变量中。这个新变量是您应该使用的，而不是 Tmap。

const CTmap = connect(... 
.... 
<CTmap/>

Answer 3

我遇到了同样的问题，我在下面解决了！

首先，你应该像下面这样导出connect输出对象↓

class Tmap extends Component { ... }

export default connect(mapStateToProps)(Tmap);

然后，然后在routes中添加导出的对象而不是class，像↓

import TmapConnectOutput from './Components/Tmap';
export const routes = <Layout>
    <Route exact path='/Tmap' component={TmapConnectOutput as any} />
</Layout>;

Answer 4

不导出 function 或 class

导出 connector class

//don't use export here
function ProductCounterPage(props) {
    const {
        ProductItem,
        OrderItemList,
        onCountChange,
        ...rest
    } = props;
    ...............
}

export default connect(mapStateToProps, null)(ProductCounterPage);

React-Redux 连接不工作

React-Redux connect not working

react-redux