React+Nodejs+mongodb存储

安装React

在此之前，请自行安装好Node和Mongodb数据库的配置

使用命令行创建文件:

npm install -g create-react-app

然后我们找到想要创建React的文件夹

1. 在需要创建项目的位置打开命令行
2. 输入create-react-app + 项目名称的命令，比如：

create-react-app Hello-World

等待完成创建后 通过CD命令进入,然后npm strat 就可以看到默认的文件了

cd Hello-World
npm start

创建后的默认目录

然后我们打开src创建一个js文件，加入我们的跨域请求端口

// In production, we register a service worker to serve assets from local cache.

// This lets the app load faster on subsequent visits in production, and gives
// it offline capabilities. However, it also means that developers (and users)
// will only see deployed updates on the "N+1" visit to a page, since previously
// cached resources are updated in the background.

// To learn more about the benefits of this model, read https://goo.gl/KwvDNy.
// This link also includes instructions on opting out of this behavior.

const isLocalhost = Boolean(
  window.location.hostname === 'localhost' ||
    // [::1] is the IPv6 localhost address.
    window.location.hostname === '[::1]' ||
    // 127.0.0.1/8 is considered localhost for IPv4.
    window.location.hostname.match(
      /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/
    )
);

export default function register() {
  if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
    // The URL constructor is available in all browsers that support SW.
    const publicUrl = new URL(process.env.PUBLIC_URL, window.location);
    if (publicUrl.origin !== window.location.origin) {
      // Our service worker won't work if PUBLIC_URL is on a different origin
      // from what our page is served on. This might happen if a CDN is used to
      // serve assets; see https://github.com/facebookincubator/create-react-app/issues/2374
      return;
    }

    window.addEventListener('load', () => {
      const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;

      if (isLocalhost) {
        // This is running on localhost. Lets check if a service worker still exists or not.
        checkValidServiceWorker(swUrl);

        // Add some additional logging to localhost, pointing developers to the
        // service worker/PWA documentation.
        navigator.serviceWorker.ready.then(() => {
          console.log(
            'This web app is being served cache-first by a service ' +
              'worker. To learn more, visit https://goo.gl/SC7cgQ'
          );
        });
      } else {
        // Is not local host. Just register service worker
        registerValidSW(swUrl);
      }
    });
  }
}

function registerValidSW(swUrl) {
  navigator.serviceWorker
    .register(swUrl)
    .then(registration => {
      registration.onupdatefound = () => {
        const installingWorker = registration.installing;
        installingWorker.onstatechange = () => {
          if (installingWorker.state === 'installed') {
            if (navigator.serviceWorker.controller) {
              // At this point, the old content will have been purged and
              // the fresh content will have been added to the cache.
              // It's the perfect time to display a "New content is
              // available; please refresh." message in your web app.
              console.log('New content is available; please refresh.');
            } else {
              // At this point, everything has been precached.
              // It's the perfect time to display a
              // "Content is cached for offline use." message.
              console.log('Content is cached for offline use.');
            }
          }
        };
      };
    })
    .catch(error => {
      console.error('Error during service worker registration:', error);
    });
}

function checkValidServiceWorker(swUrl) {
  // Check if the service worker can be found. If it can't reload the page.
  fetch(swUrl)
    .then(response => {
      // Ensure service worker exists, and that we really are getting a JS file.
      if (
        response.status === 404 ||
        response.headers.get('content-type').indexOf('javascript') === -1
      ) {
        // No service worker found. Probably a different app. Reload the page.
        navigator.serviceWorker.ready.then(registration => {
          registration.unregister().then(() => {
            window.location.reload();
          });
        });
      } else {
        // Service worker found. Proceed as normal.
        registerValidSW(swUrl);
      }
    })
    .catch(() => {
      console.log(
        'No internet connection found. App is running in offline mode.'
      );
    });
}

export function unregister() {
  if ('serviceWorker' in navigator) {
    navigator.serviceWorker.ready.then(registration => {
      registration.unregister();
    });
  }
}

index.js中的代码块：

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import 'bootstrap/dist/css/bootstrap.css';
import 'bootstrap/dist/css/bootstrap-theme.css';
import registerServiceWorker from './registerServiceWorker';

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

然后在src里面创建一个组件之后导入到index.js里面来使用 我在这里创建了一个list.jsx的组件，下面是组件的代码：

import React from 'react';
import 'bootstrap/dist/css/bootstrap.css';
import './list.css';
import axios from 'axios';
var url = 'http://localhost:3000/'  //配置远程图片的默认地址
axios.defaults.baseURL = 'http://localhost:3000/'; //axios默认请求的域名或ip地址


class TrData extends React.Component{
  constructor(props){
    super(props);
    this.state = {}
  }
  render(){
    return (
      this.props.products.map((product,i)=>{ //使用map循环遍历渲染数据库中的数据
      return (
          <tr key={product._id} className="text-center">
            <td>{product.title}</td>
            
            <td>
              <img src={url+product.defaultImage} width="100" alt=""/>
            </td>
            <td>{product.category.title}</td>
            <td>{product.price}</td>
            <td>
              <button type="button" className="btn btn-default">修改</button>

              <button type="button" className="btn btn-danger">删除</button>
            </td>
          </tr>
      )       
  
      })
    )
  }
}
class List extends React.Component {
	constructor(props){
    super(props);
    this.state={
      products:[], // 默认为空
      isLoaded:false,
    }
  }
  componentDidMount(){
    const _this=this;
    axios.get('/v1/shop/commodity/getlist')
    .then(function (response) {
      _this.setState({
        products:response.data.data.list, //请求到的数据
        isLoaded:true
      });
    })
    .catch(function (error) {
      console.log(error);
      _this.setState({
        isLoaded:false,
        error:error
      })
    })

  }

  render() {
    //条件渲染 与Vue的 V-if相似
      if(!this.state.isLoaded){
        return <div>Loading</div>
      }else{
      return (
        <table className="table table-striped">
          <thead>
            <tr>
              
              <th className="text-center">商品名称</th>
              <th className="text-center">商品图片</th>
              <th className="text-center">商品分类</th>
              <th className="text-center">商品价格</th>
              <th className="text-center">操作</th>

            </tr>
          </thead>
        <tbody>
           <TrData products={this.state.products}/>
        </tbody>
        </table>
      )  
    }
  }
}
export default List;//导出List组件

App.js中把list.jsx组件导入进来

import List from './List.jsx'; //导入list组件

class App extends Component {
  constructor(props){
    super(props); // 继承父类属性
    this.state={ }
  }
//渲染list
  render() {
    return (
      <div className="container"> //这里也可以写样式，我这里写的是Bootstrap的一个样式
        <List /> //组件
      </div>
    );
  }
}

然后把后台的地址以及Mongo数据库开启,对了这里忘了说了,因为NodeJS和ReactJS的默认端口都是localhost:3000 我们可以先把React的启动端口修改一下 在package.json的Start项里面修改为

"start": "set PORT = 9000 && react-scripts start"

至此，我们的数据渲染就大功告成了