javascript - React JS - 路由 - 元素类型无效

Question

我是 React JS 的新手，正在尝试实现类似于 Angular 示例应用程序的东西。

我有一张客户表，想在表的底部看到选定的客户。

我用 react-router-dom 尝试了以下操作:

// index.js 
import React from 'react';
import ReactDOM from 'react-dom';
import { BrowserRouter } from 'react-router-dom';
import './index.css';
import App from './App';
import registerServiceWorker from './registerServiceWorker';
import 'bootstrap/dist/css/bootstrap.css';

ReactDOM.render((<BrowserRouter><App /></BrowserRouter>), document.getElementById('root'));
registerServiceWorker();


// App.js
import React, { Component } from 'react';
import { Route } from 'react-router-dom/Route';

import Customers from './components/customers';
import Customer from './components/customer';

export default class App extends Component {
    state = {
    };

    render() {
        return (
            <React.Fragment>
                <Customers />
                <Route path={`/customer/:id`} component={Customer} />
            </React.Fragment>
        );
    }
}


// customers.jsx
import React, { Component } from 'react';
import { Link } from 'react-router-dom';

export default class Customers extends Component {
    state = {
        customers: []
    };

    render() {
        return (
            <React.Fragment>
                <header className="jumbotron"><h1>Customer List</h1></header>

                <div className="container">
                    <table className="table table-striped">
                        <thead>
                            <tr>
                                <th>Name</th>
                                <th>Address</th>
                            </tr>
                        </thead>
                        <tbody>
                            {this.state.customers.map(c => (<tr key={c.id}><td><Link to={`/customer/${c.id}`}>{c.name}</Link></td><td>{c.address}</td></tr>))}
                        </tbody>
                    </table>
                    <hr />
                </div>

                <footer className="footer">&copy; 2018</footer>
            </React.Fragment>
        );
    }

    async componentDidMount() {
        const result = await fetch('http://api.com/customers');
        const customers = await result.json();
        this.setState({ customers });
        console.log(this.state.customers);
    }
}


// customer.jsx
import React, { Component } from 'react';

export default class Customer extends Component {
    render() {
        return (<p>Customer</p>);
    };
}

App.js 中添加路由的行 (Route path={/customer/:id} component={Customer}) 导致错误。如果我删除该行，我可以看到客户表，但一旦我添加该行，我就会收到该错误消息。

我是不是错过了关于这个路由器如何工作的一些信息？

谢谢。

更新

将 App.js 更改为这个非常简单的版本的事件会导致错误

import React, { Component } from 'react';
import { Route } from 'react-router-dom/Route';

export default class App extends Component {
    state = {
    };

    render() {
        return (
            <div>
                <Route exact path='/' render={() => (<h1>Hello</h1>)} />
                <Route exact path='/customer' render={() => (<h1>Customer</h1>)} />
            </div>
        );
    }
}

完整的错误信息是:

元素类型无效:应为字符串(对于内置组件)或类/函数(对于复合组件)但得到:未定义。您可能忘记了从定义组件的文件中导出组件，或者您可能混淆了默认导入和命名导入。

Answer 1

改变这个:

import {Route} from "react-router-dom/Route";

为此:

import Route from "react-router-dom/Route";

当您直接访问它时，路由是默认导出:"react-router-dom/Route"从基础包导入 Route 时可以使用命名导出

import {Route} from "react-router-dom";

但不要将两者混为一谈。