如何在Sequelize中实现多对多关系?

Question

这些是我的模型:员工

const { DataTypes } = require('sequelize');
const sequelize = require('../sequelize')
const Staff = sequelize.define('Staff', {
name: {
type: DataTypes.STRING,
allowNull: false,
},
SSN: {
type: DataTypes.INTEGER,
},
email:{
type: DataTypes.STRING,
}
}, {
timestamps: true
});
Staff.associate = function (models) {
Staff.belongsToMany(models.Technology, {through: models.StaffTechnology});
};
module.exports = Staff;

技术:

const { DataTypes } = require('sequelize');
const sequelize = require('../sequelize')

const Technology = sequelize.define('Technology', {
name: {
type: DataTypes.STRING,
allowNull: false,
},
description: {
type: DataTypes.STRING,
}
}, {
timestamps: true
});
Technology.associate = function (models) {
Technology.belongsToMany(models.Staff, { through: models.StaffTechnology});
};
module.exports = Technology;

这将是连接表:

const { DataTypes } = require('sequelize');
const sequelize = require('../sequelize')
const Staff = require('../../database/models/staff.model');
const Technology = require('../../database/models/technology.model');

const StaffTechnology = sequelize.define('StaffTechnology', {
experience: {
type: DataTypes.INTEGER,
},
StaffID: {
type: DataTypes.INTEGER,
references: {
model: Staff, 
key: 'id'
}
},
TechnologyID: {
type: DataTypes.INTEGER,
references: {
model: Technology,
key: 'id'
}
},
}, {
timestamps: true
});
StaffTechnology.associate = function (models) {
//StaffTechnology.hasMany(models.Staff, { foreignKey: 'StaffID' });
//StaffTechnology.hasMany(models.Technology, { foreignKey: 'TechnologyID' });
};
module.exports = StaffTechnology

现在我不能做Staff. findall ({include:Technology})，因为它给了我一个错误，说Staff和Technology不相关，但我看到了Sequelize文档，我看到了一个非常类似的例子。我想要的是有可能将所有员工的技术归还给他们，员工可以拥有许多技术，技术可以属于许多员工，但实际上它们是通过StaffTechnology连接表连接起来的。

Answer 1

您需要在index.js(或初始化DB的地方)中声明关联。您可以通过直接通过要求模型和执行

来声明关联来手动完成它。

Model1.association(Model2, {
through: "JoinTable"
}
Model2.association(Model1, {
through: "JoinTable"
}

或者以编程方式(如果您已经使用该方法初始化数据库):

'use strict'

const fs = require('fs');
const path = require('path');
const Sequelize = require('sequelize');
const basename = path.basename(__filename);
const config = {
"username": "root",
"password": "YOUR ROOT PASSWORD HERE",
"database": "YOUR DATABASE NAME HERE",
"host": "127.0.0.1",
"dialect": "mysql"
}
const db = {}

let sequelize = new Sequelize(config.database, config.username, config.password, config);

fs.readdirSync(__dirname)
.filter(file => {
return (file.indexOf('.') !== 0)
&& (file !== basename)
&& (file.slice(-3) === '.js');
})
.forEach(file => {
const model = require(path.join(__dirname, file))(sequelize, Sequelize.DataTypes);
db[model.name] = model;
});

Object.keys(db).forEach(modelName => {
if (db[modelName].associate) {
db[modelName].associate(db);
}
});

db.sequelize = sequelize;
db.Sequelize = Sequelize;

module.exports = db;

^这段代码同时完成了初始化和关联。您需要确保您的模型文件和初始化文件在同一个文件夹中。