React-router 在导航栏中添加 Link

Question

React 新手，我正在尝试使用 React-router v4 在我的 material-ui 工具栏中添加一个 link 到主页，但我不断收到错误消息：

Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in. Check the render method of LandingToolBar.

我试图在此处复制基本示例 https://reacttraining.com/react-router/web/example/basic，而是将顶部列表放在另一个名为 LandingToolBar 的组件中，但我看不到它可以正常工作。这是我的 index.js:

import React from 'react'
import ReactDOM from 'react-dom'
import App from './App'
import injectTapEventPlugin from 'react-tap-event-plugin'
import MuiThemeProvider from 'material-ui/styles/MuiThemeProvider';


injectTapEventPlugin();

ReactDOM.render(
    <MuiThemeProvider>
            <App />
    </MuiThemeProvider>,
    document.getElementById('app')
);

我的app.js：

import React from 'react'
import {Route, BrowserRouter, Switch} from 'react-router-dom'
import LoginPage from "./containers/LoginPage";
import SignUpPage from "./containers/SignUpPage";
import HomePage from "./components/landing/HomePage";
import LandingToolBar from "./components/landing/LandingToolBar";

class App extends React.Component {
    render() {
        return (
            <BrowserRouter>
                <div>
                    <LandingToolBar/>
                    <Switch>
                        <Route path="/" exact component={HomePage}/>
                        <Route path="/login" component={LoginPage}/>
                        <Route path="/signup" component={SignUpPage}/>
                    </Switch>
                </div>
            </BrowserRouter>
        )
    }
}

export default App;

以及我始终尝试呈现的工具栏组件 LandingToolBar：

import React from 'react';
import Link from 'react-router-dom';
import {ToolbarGroup, ToolbarTitle, RaisedButton, Toolbar} from 'material-ui'    

const LandingToolBar = () => (
    <Toolbar>
        <ToolbarGroup>
            <ToolbarTitle text="ETFly"/>
            <Link to="/">feafeaf</Link>
        </ToolbarGroup>
    </Toolbar>
);

export default LandingToolBar;

由于文档或 v4 内容中似乎没有太多解释，因此在路由部分上苦苦挣扎...

感谢您的帮助！

Answer 1

你需要像这样 import Link，它是 named import 而不是 default import:

import {Link} from 'react-router-dom';

检查

的答案

React-router 在导航栏中添加 Link

React-router adding Link in navbar

javascript

reactjs

react-router

material-ui