Sequelize 模型联接

问：

我正在使用 Node 和 Express、Sequelize 和 PostgreSql 构建一个 API。

我的员工将属于一个且只有一个部门。我有两张桌子，员工和部门。

我的项目中有以下两个模型，我使用 .关联和外键生成似乎按预期工作，当我浏览 PostgreSql 时，我看到了 fk 约束。sequelize-cli

employee model

'use strict';
const {
  Model
} = require('sequelize');
module.exports = (sequelize, DataTypes) => {
  class Employees extends Model {
    /**
     * Helper method for defining associations.
     * This method is not a part of Sequelize lifecycle.
     * The `models/index` file will call this method automatically.
     */
    static associate(models) {
      // define association here
    }
  }
  Employees.init({
    first_name: {
      type: DataTypes.STRING,
      allowNull: false
    },
    last_name: {
      type: DataTypes.STRING,
      allowNull: false
    },
    departmentId: {
      type: DataTypes.STRING,
      allowNull: false
    },
    createdBy: {
      type: DataTypes.STRING,
      allowNull: false
    },
    updatedBy: {
      type: DataTypes.STRING
    }
  }, {
    sequelize,
    modelName: 'Employees',
  });
 
  // UPDATED per suggestions
  Employees.associate = function(models) {
    Employees.belongsTo(models.Departments, {
      foreignKey: 'departmentId',
      as: "dept",
      onDelete: 'SET NULL',
    });
  };

  return Employees;
};

departments model

'use strict';
const {
  Model
} = require('sequelize');
module.exports = (sequelize, DataTypes) => {
  class Departments extends Model {
    /**
     * Helper method for defining associations.
     * This method is not a part of Sequelize lifecycle.
     * The `models/index` file will call this method automatically.
     */
    static associate(models) {
      // define association here
    }
  }
  Departments.init({
    name: {
      type: DataTypes.STRING,
      allowNull: false
    },
    description: {
      type: DataTypes.STRING
    },
    createdBy: {
      type: DataTypes.STRING,
      allowNull: false
    },
    updatedBy: {
      type: DataTypes.STRING
    }
  }, {
    sequelize,
    modelName: 'Departments',
  });

  // UPDATED per suggestions
  Departments.associate = function(models) {
    Departments.hasMany(models.Employees, {
      foreignKey: 'departmentId',
      as: "employees"
    });
  };

  return Departments;
};

employees migration

      departmentId: {
        type: Sequelize.INTEGER,
        onDelete: 'SET NULL',
        references: {
          model: {
            tableName: 'Departments',
          },
          key: 'id',
        },
      },

这一切似乎都运行良好，如果我尝试创建没有有效部门 ID 的员工，我会按预期收到约束错误。

当我找到所有员工使用时，我会收到如下所示的回复const employees = await this.db.employees.findAndCountAll();

{
    "count": 1,
    "rows":
    [
        {
            "id": 1,
            "first_name": "jon",
            "last_name": "doe",
            "departmentId": 1,
            "createdBy": "jane.dough"
        }
    ]
}

这一切都按预期工作。

顶级域名;

但是，当我尝试包含模型（将部门名称与部门 ID 连接起来）时Departmentsconst employees = await this.db.employees.findAndCountAll({include: [{model: this.db.departments,as: 'dept'}]});

I get the following association error.
"SequelizeEagerLoadingError: Departments is not associated to Employees!"

如何修复关联以将它们连接在一起。

更新： 在应用了 @nazrul-chowdhury 建议的更改后，我仍然看到错误。

我正在发布如何初始化数据库和模型的相关代码......我想我可能在我的过程中出了点问题。

employeeRepository.js

const { connect } = require('../config/db.config');


class EmployeeRepository {

    db = {};

    constructor() {
        this.db = connect();

    }

    async getEmployees() {
        try {
            const employees = await this.db.employees.findAndCountAll({include: [{model: this.db.departments,as: 'dept'}]});

db.config

const { Sequelize, Model, DataTypes } = require("sequelize");
// const logger = require('../logger/api.logger');

const connect = () => {

    const hostName = process.env.HOST;
    const userName = process.env.USER;
    const password = process.env.PASSWORD;
    const database = process.env.DB;
    const dialect = process.env.DIALECT;
    
    const sequelize = new Sequelize(database, userName, password, {
        host: hostName,
        dialect: dialect,
        operatorsAliases: 0,
        pool: {
            max: 10,
            min: 0,
            acquire: 20000,
            idle: 5000
        },
        logging: false
    });
    // turn off logging in production (log to console in all other environments)
    // logging: process.env.NODE_ENV === 'production' ? false : console.log

    const db = {};
    db.Sequelize = Sequelize;
    db.sequelize = sequelize;
    db.departments = require("../models/departments.model")(sequelize, DataTypes, Model);
    db.employees = require("../models/employees.model")(sequelize, DataTypes, Model);

    return db;

}

module.exports = {
    connect
}