【Node学习总结-07】

以MongoDB为数据库的简单的Node.js的Demo

1. 项目目录

2. 安装

npm init -y

npm install koa koa-router --save

npm install mongodb mongoose --save

3. db.js 

const mongoose = require('mongoose')

const DB_URL = 'mongodb://localhost/itcast'

mongoose.connect(DB_URL)

mongoose.connection.on('connected',function() {
    console.log('Mongoose connection open to '+DB_URL);
});
/**
 * 连接异常 error 数据库连接错误
 */
mongoose.connection.on('error',function(err) {
    console.log('Mongoose connection error: '+ err);
});
/**
 * 连接断开 disconnected 连接异常断开
 */
mongoose.connection.on('disconnected',function() {
    console.log('Mongoose connection disconnected');
});

module.exports = mongoose

【提示】操作的数据库是mongodb的itcast数据库 

4. db/student.js

// db/index.js
const mongoose = require('./db')
const Schema = mongoose.Schema;

const studentSchema = new Schema({
    username: String,
    password: String,
    email: String

});

const MyModel = mongoose.model('users', studentSchema);


class Mongodb {
    constructor () {

    }
// 查询
    query () {
        return new Promise((resolve, reject) => {
            MyModel.find({}, (err, res) => {
                if(err) {
                    reject(err)
                }
                resolve(res)
            })
        })
    }
// 保存
    save (obj) {
        const m = new MyModel(obj)
        return new Promise((resolve, reject)=> {
            m.save((err, res) => {
                if (err) {
                    reject(err)
                }
                resolve(res)
                console.log(res)
            })
        })

    }
}
module.exports = new Mongodb()

【提示】操作的数据表是test数据库下面的users数据表

5. routers/student.js

const Router = require("koa-router")
const router = new Router()
const db = require('../db/student')

router.get('/show',async ctx=>{
    // console.log(JSON.stringify(db.query()))
     ctx.body= await db.query()
})


module.exports=router.routes()

6. app.js

const Koa=require("koa")
const KoaRouter= require("koa-router")
const app = new Koa()
const router = new KoaRouter()
const students = require('./routers/student')

router.use('/student',students)

//路由的配置
app.use(router.routes()).use(router.allowedMethods())


app.listen(3000,function (res,req) {
    console.log("Server start at 3000...")
})

7. 测试

扩展：Koa连接Mysql

比较简单，与Express连接基本相同。参考https://www.jianshu.com/p/d54e055db5e0