大家可以前往 Sequelize中文文檔，查看 Sequelize不同版本【5.x、4.x】的文檔

本文檔分多個(gè)篇章，難易程度從低到高，學(xué)習(xí)此篇章之前，務(wù)必確保自己已經(jīng)掌握 node.js、express、es6語法、mysql等關(guān)系型數(shù)據(jù)庫的sql語法等

一對(duì)多

以下例子可能不恰當(dāng)，但是不要較真，跟著思路走就對(duì)了。
舉個(gè)栗子： 假設(shè)一個(gè)人（id）可以有多個(gè)愛好（id），那么這種模式就是一對(duì)多

模型定義

我這里為了方便理解就不把hobbys表的模型拎出去了

import {Sequelize, DataTypes} from 'sequelize'
import sequelize from './../connection'

const User = sequelize.define('user', {
    username: DataTypes.STRING,
    gender: {
        type: DataTypes.INTEGER,
        defaultValue: 1,
    },
    age: {
        type: DataTypes.INTEGER,
        defaultValue: 20
    },
    headImg: {
        type: DataTypes.STRING,
        defaultValue: 'img.png'
    }
});
const Hobby = sequelize.define('hobby',
    {
        hobbyName: {
            type: DataTypes.CHAR(20),
            allowNull: false
        }
    }
);

//User的實(shí)例對(duì)象將擁有g(shù)etHobby、setHobby、addHobby、createHobby、removeHobby、hasHobby方法
let Hobbies = User.hasMany(Hobby, {as: 'Hobbies'});//讓user實(shí)例可以調(diào)用getHobbies 和 setHobbies
//Hobby的實(shí)例對(duì)象將擁有g(shù)etUser、setUser、createUser方法
Hobby.belongsTo(User);

User.sync({force: true}).then(d=> {//表同步完成后注釋掉
    console.log('users表同步完成');
    Hobby.sync({force: true}).then(d=> {
        console.log('Hobby表同步完成');
    });
});

export default {User,Hobby,Hobbies}

關(guān)系操作

增加數(shù)據(jù)

方法一

User.Controller.js

insertUserHobby: async (req, res, next) => {
        let {username, hobbyName} = req.body;
        let user = await User.User.create({username});
        let hobby = await user.createHobby({hobbyName});
        res.send({
            code: 200,
            hobby
        })
    },

方法二

User.Controller.js

insertUserHobbies: async (req, res, next) => {
        let {username, hobbyName} = req.body;
        let user = await User.User.create({username});
        let hobby1 = await User.Hobby.create({hobbyName});//插入一條hobby數(shù)據(jù)，此時(shí)該條數(shù)據(jù)的外鍵userId為空
        let hobby2 = await User.Hobby.create({hobbyName: '籃球'});//這里我就不接收了，直接賦值了
        hobby1 = await user.addHobby(hobby1);//使用user的屬性id值再更新該條hobby數(shù)據(jù)，設(shè)置好外鍵，完成關(guān)系建立
        hobby2 = await user.addHobby(hobby2);//新增多個(gè)愛好
        res.send({
            code: 200,
            hobby1,hobby2
        })
    },

修改數(shù)據(jù)

User.Controller.js

updateUserHobbies: async (req, res, next)=>{
        let {id, hobbyName} = req.body;
        let user = await User.User.findOne({where: {id}});
        let upHobby = await User.Hobby.create({hobbyName});
        let upHobby2 = await User.Hobby.create({hobbyName: '愛好2'});
        let updateHobby = await user.setHobbies([upHobby, upHobby2]);
        res.send({
            code: 200,
            data: '修改成功',
            updateHobby
        })
    },

修改數(shù)據(jù)

刪除數(shù)據(jù) 實(shí)際上是將關(guān)聯(lián)的userId設(shè)置為null

User.Controller.js

deleteUserHobbies: async (req, res, next)=>{
        let {id} = req.body;
        let user = await User.User.findOne({where: {id}});//通過id查詢用戶
        let deleteHobby = await user.setHobbies([]);
        res.send({
            code: 200,
            data: '刪除成功',
            deleteHobby
        })
    },

查詢數(shù)據(jù)

查詢user的所有滿足條件的hobby數(shù)據(jù)。

User.Controller.js

getHobbies : async (req, res, next)=>{
        let {id} = req.query;
        let user = await User.User.findByPk(id);
        let Hobbies = await user.getHobbies({
            attributes: ['hobbyName','userId']
        });
        res.send({
            code: 200,
            hobbies
        })
    }

postman

{
    "code": 200,
    "hobbies": [
        {
            "hobbyName": "練習(xí)生",
            "userId": 4
        },
        {
            "hobbyName": "籃球",
            "userId": 4
        }
    ]
}

查詢所有滿足條件的hobby，同時(shí)獲取hobby屬于哪個(gè)user。

User.Controller.js

getUserHobbies: async (req, res, next)=>{
        let {id} = req.query;
        let hobbies = await User.Hobby.findAll({
            where: {userId: id},
            include: [{
                model: User.User,
                attributes: ['username']
            }],
            attributes: ['hobbyName','userId']
        });
        res.send({code: 200, hobbies})
    }

postman

{
    "code": 200,
    "hobbies": [
        {
            "hobbyName": "練習(xí)生",
            "userId": 4,
            "user": {
                "username": "Mjhu"
            }
        },
        {
            "hobbyName": "籃球",
            "userId": 4,
            "user": {
                "username": "Mjhu"
            }
        }
    ]
}

查詢所有滿足條件的user，同時(shí)獲取該user所有滿足條件的hobby。

User.Controller.js

getUserInfo: async (req, res, next)=>{
        let {id} = req.query;
        let userAndHobbies = await User.User.findOne({
            where: {id},
            attributes: ['username','gender'],
            include: [{
                association: User.Hobbies,
                attributes: ['hobbyName']
            }]
        });
        res.send({code: 200, userAndHobbies})
    }

postman

{
    "code": 200,
    "userAndHobbies": {
        "username": "Mjhu",
        "gender": 1,
        "Hobbies": [
            {
                "hobbyName": "練習(xí)生"
            },
            {
                "hobbyName": "籃球"
            }
        ]
    }
}

好了，到此為止，一對(duì)多的關(guān)系就已經(jīng)結(jié)束了，下一章節(jié)我們會(huì)介紹 [Sequelize V6.20.1 中數(shù)據(jù)表的關(guān)系：多對(duì)多