koa2+sequelize初探

項(xiàng)目結(jié)構(gòu)

1. controllers：請(qǐng)求后的事件
2. mdel：sequelize數(shù)據(jù)模型
3. routes：路由分發(fā)
4. views：使用ejs模板引擎
5. app.js：項(xiàng)目入口
6. config.js：配置文件

sequelize

入口

const Sequelize = require('sequelize');
const config = require('../config');
exports.sequelize = function () {
    return new Sequelize(
        config.mysql.database,
        config.mysql.username,
        config.mysql.password, {
            'dialect': 'mysql', // 數(shù)據(jù)庫(kù)使用mysql
            'host': config.mysql.host, // 數(shù)據(jù)庫(kù)服務(wù)器ip
            'port': config.mysql.port, // 數(shù)據(jù)庫(kù)運(yùn)行端口
            'timestamp': true, // 這個(gè)參數(shù)為true是MySQL會(huì)自動(dòng)給每條數(shù)據(jù)添加createdAt和updateAt字段
            'quoteIdentifiers': true
        }
    );
};

定義數(shù)據(jù)模型

module.exports = function (sequelize, DataTypes) {
    return sequelize.define('student', {
        sid: {
            type: DataTypes.STRING(50),
            primaryKey: true
        },
        name: {
            type: DataTypes.STRING(100)
        },
    })
}

確定關(guān)聯(lián)

const db = require('./db').sequelize();
let student = db.import('./student');
let course = db.import('./course');

// 同步模型到數(shù)據(jù)庫(kù)中
//多對(duì)多模型通過中間表方式簡(jiǎn)歷聯(lián)系
course.belongsToMany(student, {
    through: 'courseToStudent',   
    foreignKey: 'sid',
})
student.belongsToMany(course, {
    through: 'courseToStudent',
    foreignKey: 'cid',

})

創(chuàng)建初始數(shù)據(jù)

 db.sync({
     alter: true
 }).then(function (result) {
     (async () => {
         let aa = await student.create({
             sid: 's-' + new Date(),
             name: '王噠四號(hào)',
             age: '17',
             sex: '男',
         });
         let bb = await course.create({
             cid: '1104',
             name: '化學(xué)',
         });
        bb.addStudent(aa)       //建立聯(lián)系
    })();
 });

多表操作

查詢

let aa = await student.findAll({
            include: {
                model: course,    //關(guān)聯(lián)數(shù)據(jù)默認(rèn)放到courses中
            }
        })

創(chuàng)建

 let aa = await student.create({
            sid: query.sid,
            name: query.name,
            age: query.age,
            sex: query.sex
        })

更新

//先更新主表非關(guān)聯(lián)部分
let cc = await student.update({
    name: query.name,  
    age: query.age,    
    sex: query.sex 
}, { 
    where: {      
        sid    
    }     
})
//拿到當(dāng)前需要改的學(xué)生       
let dd = await student.findOne({
    where: {  
        sid   
    }  
}) 
//通過參數(shù)獲得當(dāng)前學(xué)生需要更改的課程
let ee = query.courses
//將所有課程找到并推入到ff
let ff = []   
for (let i = 0; i < ee.length; i++) {      
    let bb = await course.findOne({        
        where: {        
            cid: ee[i]        
        }       
    })           
    ff.push(bb)        
}        
//更改當(dāng)前學(xué)生的課程關(guān)聯(lián)
dd.setCourses(ff)

刪除

let aa = await student.destroy({
            where: {
                sid
            }
        })

koa2

監(jiān)聽端口

const Koa = require('koa')
const app = new Koa();
const config = require('./config');

app.listen(config.port, function listening() {
    console.log('服務(wù)器啟動(dòng)成功！端口：', config.port)
})

引入模板引擎

const views = require('koa-views')
app.use(views(__dirname + '/views', {
    extension: 'ejs'
}))

路由分發(fā)

1. 引入

const router = require('./routes')
app.use(router.routes()).use(router.allowedMethods());

2. 具體操作

router.get('/', async (ctx) => {
    try {
        //查詢數(shù)據(jù)庫(kù)，拿到數(shù)據(jù)卦溢，返回給前端
        let aa = await student.findAll({
            include: {
                model: course,
            }
        })
        // ctx.body = aa
        await ctx.render('index', {
            students: aa
        })
    } catch (e) {
        return ctx.body = {
            msg: '獲取信息失敗',
            ab: e,
            code: -1
        }
    }
})