如何使用 Sequelize.js 建立表之间的多对多关系？

Question

我想通过使用 Sequelize.js 在 Events 表和 Users 表之间建立多对多关系。一个用户可以参加更多的活动，一个活动有更多的参与者。因此，我带来了一个 event_user 的中间表，并创建了它的模型。

以下是所有 3 个模型：

我的 users_model.js：

var EventUser = require('./event_user_model.js');

//_______________________Init & Config Sequelize__________________

const Sequelize = require("sequelize");
const sequelize = new Sequelize('db', 'root', '', {
  host: 'localhost',
  dialect: 'mysql',
  pool: {
    max: 5,
    min: 0,
    idle: 10000
  }
});
//____________Declare table structure ________________________

var User = sequelize.define('user', {
  id: {
    type: Sequelize.STRING,
    primaryKey: true, 
    },
  password: { 
    type: Sequelize.STRING,
  },
  email: {
    type: Sequelize.STRING
  },   
  user_id: { //Foreign Key. Do I even need to put it here at all?
    type: Sequelize.INTEGER,
    references: {
      model: "events_user",
      key: "user_id",
     } 
  },

}, {
  freezeTableName: true
});

//__________________Establish relationships with other tables_________


User.belongsTo(EventUser,{foreignKey:user_id});

//_____________________________________________________________________

User.sync({force:true}).then(function () {
  return User.create({
    id:'ORD0',
    password: 'mypass',
    email: 'whatever@gmail.com',
    user_id:1    
  });
}).then(c => {
    console.log("User Created", c.toJSON());
})
.catch(e => console.error(e));

//______________________________________________________________________

module.exports = User;

我的 events_model.js：

var EventUser = require('./event_user_model.js');

//______________Init & Config Sequelize_________
const Sequelize = require("sequelize");
const sequelize = new Sequelize('millesime_admin', 'root', '', {
  host: 'localhost',
  dialect: 'mysql',
  pool: {
    max: 5,
    min: 0,
    idle: 10000
  }
});
//______________________Declare table structure __________________

var Event = sequelize.define('event', {    
  eventid: { 
    type: Sequelize.INTEGER,
    primaryKey: true, 
    autoIncrement: true,        
    },
  date: {
    type: Sequelize.DATE
  },
  title: {
    type: Sequelize.STRING,
  },   
  event_id: { //Foreign Key . Do I even need to put it here at all?
    type: Sequelize.INTEGER,
    references: {
      model: "event_user",
      key: "event_id" // Surely here I do something wrong!!
    }
  },     

}, {
  freezeTableName: true 
});

//____________Establish relationships with other tables_________

Event.belongsTo(EventUser, {foreignKey: event_id});

//________________________Create table____________
Event.sync().then(function () {

  return Event.create({
    eventid:1,
    title: 'Event1',
    date: new Date(24, 9, 2016),
    event_id: 1,        
  });
}).then(c => {
    console.log("Created event", c.toJSON());
}).catch(e => console.error(e));

//________________________________________________________
    module.exports = Event; 

还有我的 event_user_model.js：

var User = require('./users_model.js');
var Event= require('./events_model.js');

//______________________________Initialize & Config Sequelize__________________
const Sequelize = require("sequelize");
const sequelize = new Sequelize('millesime_admin', 'root', '', {
  host: 'localhost',
  dialect: 'mysql',
  pool: {
    max: 5,
    min: 0,
    idle: 10000
  }
});
//_______________Declare table structure ________________________
var EventUser = sequelize.define('eventuser', {    
  eventuserid: { 
    type: Sequelize.INTEGER,
    primaryKey: true,
    autoIncrement: true,
    },
  user_id: {
    type: Sequelize.INTEGER,
    references: {
      model: "users",
      key: "id",
     }   
  },
  event_id: { 
    type: Sequelize.INTEGER,
    references: {
       model: "event",
       key: "eventid",
     }   
  },
 reservationConfirmation:{
    type:Sequelize.BOOLEAN,
 },
 attendance:{
    type:Sequelize.BOOLEAN
 },
},
{
  freezeTableName: true 
});

//___________________Establish relationships with other tables_________

EventUser.hasMany(User, {foreignKey:id});
//EventUser.hasMany(Event, {forignKey:eventid});
//__________________________Create table_______________________
EventUser.sync( /*{force: true}*/ ).then(function () {
  return EventUser.create({
    eventuserid:1,
    event_id:1,
    user_id: 1,
    reservationConfirmation: true,
    attendance: true    
  });
}).then(c => {
    console.log("Created", c.toJSON());
}).catch(e => console.error(e));   
//___________________________________________________
 module.exports = EventUser;

Answer 1

您做的第一件事是在每个模型文件中创建新的 Sequelize 实例。您需要创建一个文件，在其中创建 sequelize 实例，该实例将在每个模型定义文件中导入。在你的情况下，结构可以如下

- models
    - sequelize.js
    - event.js
    - user.js
    - eventUser.js

每个文件都应该是这样的：

// sequelize.js
var Sequelize = require('sequelize');

var sequelize = new Sequelize(
    'millesime_admin',
    'root',
    '',
    {
        host: 'localhost',
        dialect: 'mysql',
        pool: {
            max: 5,
            min: 0,
            idle: 10000
       }
    }
);

module.exports = sequelize;

现在，当您创建了 sequelize 实例后，您可以定义模型

// event.js
var sequelize = require('./sequelize');

var Event = sequelize.define(...);

module.exports = Event;

// user.js
var sequelize = require('./sequelize');

var User = sequelize.define(...);

module.exports = User;

现在您可以创建最后一个模型EventUser，以及Event 和User 之间的多对多关系。这个关系将在EventUser 模型定义发生的eventUser.js 文件中创建

// eventUser.js
var sequelize = require('./sequelize');
var User      = require('./user');
var Event     = require('./event');

var EventUser = sequelize.define(...);

User.belongsToMany(Event, { through: EventUser } );
Event.belongsToMany(User, { through: EventUser } );

Answer 2

参见 BelongsToMany mixin：“与连接表的多对多关联。”

例子：

UserProject = sequelize.define('user_project', {
  role: Sequelize.STRING
});
User.belongsToMany(Project, { through: UserProject });
Project.belongsToMany(User, { through: UserProject });    

查看文档：

• http://docs.sequelizejs.com/en/v3/api/associations/belongs-to-many/