starr-philproperties/apps/api/database/migrations/20270101000010-create-course-prerequisites.js

'use strict';

module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.createTable('course_prerequisites', {
      prereq_id:   { type: Sequelize.BIGINT, primaryKey: true, autoIncrement: true },
      course_id:   { type: Sequelize.BIGINT, allowNull: false, references: { model: 'courses', key: 'course_id' }, onDelete: 'CASCADE' },
      ref_type:    { type: Sequelize.ENUM('course', 'unit', 'lesson'), allowNull: false },
      ref_id:      { type: Sequelize.BIGINT, allowNull: false },
      order_index: { type: Sequelize.INTEGER, defaultValue: 0 },
      createdAt:   { type: Sequelize.DATE, allowNull: false },
      updatedAt:   { type: Sequelize.DATE, allowNull: false },
    });

    await queryInterface.addIndex('course_prerequisites', ['course_id']);
  },

  async down(queryInterface) {
    await queryInterface.dropTable('course_prerequisites');
  },
};