Sequelize：带有关联的种子

Question

例如，我有 2 个模型，课程和视频。课程有很多视频。

// course.js
'use strict';

module.exports = (sequelize, DataTypes) => {
  const Course = sequelize.define('Course', {
    title: DataTypes.STRING,
    description: DataTypes.STRING
  });

  Course.associate = models => {
    Course.hasMany(models.Video);
  };

  return Course;
};


// video.js
'use strict';

module.exports = (sequelize, DataTypes) => {
  const Video = sequelize.define('Video', {
    title: DataTypes.STRING,
    description: DataTypes.STRING,
    videoId: DataTypes.STRING
  });

  Video.associate = models => {
    Video.belongsTo(models.Course, {
      onDelete: "CASCADE",
      foreignKey: {
        allowNull: false
      }
    })
  };

  return Video;
};

我想用包含视频的课程创建种子。我怎样才能做到？我不知道如何使用包含的视频创建种子。

Answer 1

您可以使用 Sequelize 的 queryInterface 下拉到原始 SQL 以插入需要关联的模型实例。在您的情况下，最简单的方法是为课程和视频创建一个播种机。 （注：我不知道你是如何定义主键和外键的，所以我假设视频表有一个字段course_id。）

module.exports = {
  up: async (queryInterface) => {
    await queryInterface.bulkInsert('courses', [
      {title: 'Course 1', description: 'description 1', id: 1}
      {title: 'Course 2', description: 'description 2', id: 2}
    ], {});

    const courses = await queryInterface.sequelize.query(
      `SELECT id from COURSES;`
    );

    const courseRows = courses[0];

    return await queryInterface.bulkInsert('videos', [
      {title: 'Movie 1', description: '...', id: '1', course_id: courseRows[0].id}
      {title: 'Movie 2', description: '...', id: '2', course_id: courseRows[0].id},
      {title: 'Movie 3', description: '...', id: '3', course_id: courseRows[0].id},
    ], {});
  },

  down: async (queryInterface) => {
    await queryInterface.bulkDelete('videos', null, {});
    await queryInterface.bulkDelete('courses', null, {});
  }
};

Answer 2

在bulkInsert 的选项字段中传递{ returning: true } 时，它将返回创建的对象。

    let createdOjects = await queryInterface.bulkInsert("table_name", data_to_be_inserted, { returning: true });

此外，您可以传递一个包含您感兴趣的字段的数组，例如ID { returning: ['id'] }，这将返回创建对象的 ID 数组

    let createdIds = await queryInterface.bulkInsert("table_name", data_to_be_inserted, { returning: ['id'] });

您也可以使用bulkInsert 循环遍历返回的对象/ID 并插入嵌套对象。

示例代码：

module.exports = {
  up: async (queryInterface) => {
    let courses = ["..."]
    let videos = ["..."]
    let videoIds = await queryInterface.bulkInsert("courses", courses, { returning: ["id"] });
    
    //add courseId to each video object -- depends on your scheme

     await queryInterface.bulkInsert("videos", videos);
  },

  down: async (queryInterface) => {
    await queryInterface.bulkDelete("videos", null, {});
    await queryInterface.bulkDelete("courses", null, {});
  },
};

Answer 3

bulkInsert 方法返回一个用第一个插入项的 ID 解析的承诺。我们可以使用这些信息来插入视频。它可能看起来像这样：

function getId( firstId, items, needly ) {
    for ( let i = 0; i < items.length; i++ ) {
        if ( items[i].title === needly ) {
            return firstId + i;
        }
    }

    return null;
}

exports.up = async ( queryInterface, Sequelize ) => {
    const courses = [
        {
            title: 'Course 1',
            description: '...',
        },
        {
            title: 'Course 2',
            description: '...',
        },
        {
            title: 'Course 3',
            description: '...',
        },
        {
            title: 'Course 4',
            description: '...',
        },
        {
            title: 'Course 5',
            description: '...',
        },
    ];

    const firstId = await queryInterface.bulkInsert( 'courses', courses, {} );
    const course2Id = getId( firstId, courses, 'Course 2' );
    const course5Id = getId( firstId, courses, 'Course 5' );

    return queryInterface.bulkInsert( 'categories', [
        { title: 'Video 1', description: '...', courseId: course2Id },
        { title: 'Video 2', description: '...', courseId: course2Id },
        { title: 'Video 3', description: '...', courseId: course5Id },
        { title: 'Video 4', description: '...', courseId: course5Id },
        { title: 'Video 5', description: '...', courseId: course5Id },
    ], {} );
};

exports.down = async ( queryInterface ) => {
    await queryInterface.bulkDelete( 'videos', null, {} );
    await queryInterface.bulkDelete( 'courses', null, {} );
}