使用Express构建RESTful API

RESTful服务

REST(Representational State Transfer)的意思是表征状态转移，它是一种基于HTTP协议的网络应用接口风格，充分利用HTTP的方法实现统一风格接口的服务。通过动词（HTTP方法）+名词（请求资源的接口路径）的方式请求资源，赋予接口特定的含义。

REST风格定义了一系列创建HTTP服务的惯例：

• POST：创建资源
• PUT：更新资源
• GET：读取资源
• DELETE：删除资源

例如：

• 获取所有书籍： GET /api/books
• 获取id为1的书籍： GET /api/books/1
• 更新id为1的书籍：PUT /api/books/1
• 删除id为1的书籍：DELETE /api/books/1
• 添加书籍：POST /api/books

Express构建RESTful API

Express.js是一个轻量且灵活的Node.js WEB应用框架，可以快速搭建WEB应用。其底层是对Node.js的HTTP模块进行封装，增加路由、中间件等特性，使得用户能搭建应用级别的WEB服务。

处理GET请求

直接上代码：

const express = require('express');
const app = express();
const Joi = require('joi');

app.use(express.json());

const books = [
    { id: 1, name: 'book1'},
    { id: 2, name: 'book2'},
    { id: 3, name: 'book3'},
];

app.get('/', (req, res) => {
    res.end('Hello World!');
});
//获取所有书籍
app.get('/api/books', (req, res) => {
    res.json(books).end();
});
//获取特定id的书籍
app.get('/api/books/:id', (req, res) => {
    let book = books.find(b => b.id === parseInt(req.params.id));
    if(!book) return res.status(404).json({msg: 'The book with the given ID not find.'});
    res.json(book).end();
});

const port = process.env.PORT || 5000;
app.listen(port, () => console.log(`Listening on port ${port}`));

GET /api/books

GET /api/books/2

GET /api/books/5

处理POST请求

function validateBook(book){
    const schema = {
        name: Joi.string().min(3).required()
    };

    return Joi.validate(book, schema);
}

//使用POST方法添加书籍
app.post('/api/books', (req, res) => {
    const {error} = validateBook(req.body);
    if(error){
        return res.status(400).json({msg: error.details[0].message}).end();
    }

    const book = {
        id: books.length + 1,
        name: req.body.name
    };
    books.push(book);
    res.json(book).end();
});

POST /api/books

处理PUT请求

//使用PUT方法修改书籍
app.put('/api/books/:id', (req, res) => {
    let book = books.find(b => b.id === parseInt(req.params.id));
    if(!book) return res.status(404).json({msg: 'The book with the given ID not find.'});
    
    const { error } = validateBook(req.body);
    if(error) return res.status(400).json({msg: error.details[0].message}).end();

    book.name = req.body.name;
    res.json(book).end();
});

PUT /api/books/1

处理DELETE

//使用DELETE方法删除书籍
app.delete('/api/books/:id', (req, res) => {
    let book = books.find(b => b.id === parseInt(req.params.id));
    if(!book) return res.status(404).json({msg: 'The book with the given ID not find.'});

    const index = books.indexOf(book);
    books.splice(index, 1);

    res.json(book).end();
});

DELETE /api/books/1