如何在NodeJS中使用Sequelize在表模型中应用外键？

Question

我正在学习如何在NodeJs中使用Sequelize来访问MySQL数据库，但是在创建模型的时候，我被外键问题困住了。有谁能建议我如何申请吗？因为我试过一个，但还是出错了。

模型

exam_category.js

const Sequelize = require('sequelize');
const sequelize = require('../../database');

const ExamCategory = sequelize.define('exam_category', {
    id:{ type: Sequelize.BIGINT, autoIncrement: true, allowNull: false, primaryKey: true }, 
    exam_category_name: { type: Sequelize.STRING, allowNull: false },
    isActive: { type: Sequelize.BOOLEAN, allowNull: false },
    createdBy: { type: Sequelize.STRING, allowNull: true },
    createdAt: { type: Sequelize.DATE, allowNull: false }
}, { timestamps: false });

module.exports = ExamCategory;

exam.js

const Sequelize = require('sequelize');
const sequelize = require('../../database');

const Exam = sequelize.define('exam', { 
    id:{ type: Sequelize.BIGINT, autoIncrement: true, allowNull: false, primaryKey: true }, 
    startDate: { type: Sequelize.STRING, allowNull: false }, 
    endDate: { type: Sequelize.STRING, allowNull: false },
    startTime: { type: Sequelize.STRING, allowNull: false }, 
    endTime: { type: Sequelize.STRING, allowNull: false },
    examDuration: { type: Sequelize.INTEGER, allowNull: false },
    examName: { type: Sequelize.STRING, allowNull: false },
    examKey: { type: Sequelize.STRING, allowNull: false, unique: true },
    exam_category_id: { type: Sequelize.BIGINT, allowNull: false, references: 'exam_category', referencesKey: 'id' },
    isActive: { type: Sequelize.BOOLEAN, allowNull: false },
    createdBy: { type: Sequelize.STRING, allowNull: true },
    createdAt: { type: Sequelize.DATE, allowNull: false }
}, { timestamps: false });

module.exports = Exam;

然后在app.js中我写了这样一个:

const sequelize = require('./database');
const adminUser = require('./models/users/admin_user');
const examCategory = require('./models/users/exam_category');
const exam = require('./models/users/exam');
examCategory.ExamCategory.hasMany(exam.Exam, {
    foreignKey: 'exam_id',
    sourceKey: 'id'
});
exam.Exam.belongsTo( examCategory.ExamCategory, {
    foreignKey: 'exam_id',
    targetKey: 'id'
});
sequelize.sync();
sequelize.sync({ force: true });

这是我的database.js。

const Sequelize = require('sequelize');
const examCategory = require('./exam_category');

const db = new Sequelize(
    'otp_node', 'root', 'root',
    {
        dialect: 'mysql',
        host: 'localhost'
    }
);
module.exports = db;

错误

PS D:PracticeOtpFrontend&>；node.server.js internal/modules/cjs/loader.js:968抛出错误；^

错误:找不到模块'./exam_category'所需堆栈:

在module._compile（internal/modules/cjs/loader.js:113730)在object.module._extensions.js（internal/modules/cjs/loader.js:1157:10)在module.load（internal/modules/cjs/loader.js:985:32)在function.module._load（internal/modules/cjs/loader.js:878:14)在

作为参考，这是我的Github回购代码。有人能帮我这个吗？

Answer 1

您可以尝试在表中添加外键

const sequelize = require('./database');
const adminUser = require('./models/users/admin_user');
const ExamCategory = require('./models/users/exam_category');
const Exam = require('./models/users/exam');
ExamCategory.hasMany(exam, {
    foreignKey: 'exam_id',
    sourceKey: 'id'
});
Exam.belongsTo( examCategory, {
    foreignKey: 'exam_id',
    targetKey: 'id'
});
sequelize.sync();
sequelize.sync({ force: true });  

在关联表的文件中添加上面的代码，它将在表中添加foreign_key作为名称exam_id，您可以给它取任意名称

您可以在此单据中了解更多的foreignKey和表间关系

检查这个存储库，以便您了解如何使用sequelize以及节点sequelize的样板