编写简单的增删改查接口

// 对本地数据user.json进行增删改查
const express = require('express');
const fs = require("fs");
const bodyParser = require("body-parser");
const app = express();

app.use(bodyParser.urlencoded({extended: false}))
app.use(bodyParser.json());


//设置跨域访问
app.all('*', function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "*");
    res.header("Access-Control-Allow-Methods", "PUT,POST,GET,DELETE,OPTIONS");
    res.header("Content-Type", "application/json;charset=utf-8");
    next();
});

/**
 * 随机生成id
 * @returns {string}
 */
function guid() {
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
        var r = Math.random() * 16 | 0,
            v = c == 'x' ? r : (r & 0x3 | 0x8);
        return v.toString(16);
    });
}

// 查询
app.get("/userlist", function(req, res) {
    fs.readFile("user.json", "utf8", function(err, data) {
        res.end(data);
    });
});

//新增
app.post("/adduser",function(req,res){
    fs.readFile("user.json", "utf8", (err, data) => {
        if (err) {throw err;}
        params={
            "name":req.body.name,
            "age":req.body.age,
            "id":guid()
        }
        var person = data.toString();//将二进制的数据转换为字符串
        person = JSON.parse(person);//将字符串转换为json对象
        person.push(params);
        var str = JSON.stringify(person);
        fs.writeFile("user.json", str, err => {
            if(err){throw err;}
            res.end();
        });
    });
});

// 删除
app.post("/delUser/:id", (req, res) => {
    const id = req.params.id;
    fs.readFile("user.json", "utf8", (err, data) => {
        data = JSON.parse(data) || [];
        const saveData = data.filter((item)=>{
            return item.id !== id;
        });
        fs.writeFile("user.json", JSON.stringify(saveData), err => {
            if (err) throw err;
            res.end();
        });
    });
});

// 修改
app.post("/update", (req, res) => {
    const id = req.body.id;
    const body = req.body;
    fs.readFile("user.json", "utf8", (err, data) => {
        const userList = (data && JSON.parse(data)) || [];
        const index = userList.findIndex(item => item.id == id);
        userList[index] = { ...userList[index], ...body };
        fs.writeFile("user.json", JSON.stringify(userList), err => {
            if (err) throw err;
            res.end();
        });
    });
});


//配置服务端口
var server = app.listen(3000, function() {})

//备注：修改和删除接口无法对比前台传过来的id,原因是因为新增的时候没有id,当全部删除之后，新增数据的时候，就没有id，从而无法比较