Redux 连接组件不渲染

Question

I'm new to redux, and currently trying to get a connected component to render, yet nothing renders. The header tag in Main.js should render, yet it doesn't. I really don't get what the problem is, there aren't any syntax errors, or compilation problems. Here's my code:

App.js:

import { bindActionCreators } from 'redux';
import { connect } from 'react-redux';

import Main from './Main';

function mapStateToProps(state) {
    return {
        //state goes here
    }
}

// eg: const actionCreators = {...allStudentActions};

function mapDispatchToProps(dispatch) {
    // return bindActionCreators(actionCreators, dispatch);
    return;
}



const App = connect(mapStateToProps, mapDispatchToProps)(Main);

export default App;

Main.js:

import React from 'react';

class Main extends React.Component {
    render() {
        return (
            <div>
                <h1>PlaceMint</h1>
              {React.cloneElement({...this.props}.children, {...this.props})}
            </div>
          )
    }
}

export default Main;

index.js

import React from 'react';
import { render } from 'react-dom';

import App from  './components/App';


// import pages components



// router dependencies
import { Route, Switch } from 'react-router';
import { BrowserRouter } from 'react-router-dom';
import { Provider } from 'react-redux';

import store from './store';





const router = (
    <Provider store={store}>
        <BrowserRouter>
                <Route path="/" component={App}>
                    <Switch>
                        {/* All the pages go here, wrapperd in react router 'Route tags' see react router docs */}
                    </Switch>

                </Route>
        </BrowserRouter>
    </Provider>
)

render(router, document.getElementById('root'));

Answer 1

I think the only problem with your code is that you should place the Route inside of Switch component so it will only render one component for the matching route.

Probably your empty Switch is the problem as there is no matching component inside your route. Move the Switch or wrap your route inside it - depends on what you're trying to create.

Switch is used to only render the first matching route. For more details, please have a looke here .

You haven't posted your store definition so I've created a simple example store in the demo below or in the following codesandbox .

Note: The code below is just for reference. I couldn't get it to run here.

 /* // import pages components import { bindActionCreators } from "redux"; import { connect } from "react-redux"; // router dependencies import { Route, Switch } from "react-router"; import { BrowserRouter } from "react-router-dom"; import { Provider } from "react-redux"; import { createStore } from "redux"; import React from "react";*/ class Main extends React.Component { render() { const { greeting } = this.props; console.log(greeting); return ( <div> <h1>PlaceMint</h1> {greeting} {/*React.cloneElement({ ...this.props }.children, { ...this.props })*/} </div> ); } } function mapStateToProps(state) { return { greeting: state.greeting //state goes here }; } // eg: const actionCreators = {...allStudentActions}; function mapDispatchToProps(dispatch) { // return bindActionCreators(actionCreators, dispatch); return { dispatch }; } const App = connect(mapStateToProps, mapDispatchToProps)(Main); const initialState = { greeting: "hello from redux" }; //import store from "./store"; const rootReducer = (state = initialState, action) => { return state; }; const store = createStore(rootReducer); const router = ( <Provider store={store}> <BrowserRouter> <Switch> <Route path="/" component={App} /> {/* All the pages go here, wrapperd in react router 'Route tags' see react router docs */} </Switch> </BrowserRouter> </Provider> ); render(router, 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> <script src="https://cdnjs.cloudflare.com/ajax/libs/redux/4.0.1/redux.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react-redux/6.0.1/react-redux.min.js"></script> <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"> <meta name="theme-color" content="#000000"> <!-- manifest.json provides metadata used when your web app is added to the homescreen on Android. See https://developers.google.com/web/fundamentals/engage-and-retain/web-app-manifest/ --> <link rel="manifest" href="%PUBLIC_URL%/manifest.json"> <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico"> <!-- Notice the use of %PUBLIC_URL% in the tags above. It will be replaced with the URL of the `public` folder during the build. Only files inside the `public` folder can be referenced from the HTML. Unlike "/favicon.ico" or "favicon.ico", "%PUBLIC_URL%/favicon.ico" will work correctly both with client-side routing and a non-root public URL. Learn how to configure a non-root public URL by running `npm run build`. --> <title>React App</title> </head> <body> <noscript> You need to enable JavaScript to run this app. </noscript> <div id="root"></div> <!-- This HTML file is a template. If you open it directly in the browser, you will see an empty page. You can add webfonts, meta tags, or analytics to this file. The build step will place the bundled scripts into the <body> tag. To begin the development, run `npm start` or `yarn start`. To create a production bundle, use `npm run build` or `yarn build`. --> </body> </html>