javascript 续集：有关联的种子
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Sequelize: seed with associations
提问by zett
I have 2 models, Courses and Videos, for example. And Courses has many Videos.
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;
};
I want to create seeds with courses which includes videos. How can I make it? I don't know how to create seeds with included videos.
我想创建包含视频的课程的种子。我怎样才能做到？我不知道如何使用包含的视频创建种子。
回答by mcranston18
You can use Sequelize's queryInterfaceto drop down to raw SQL in order to insert model instances that require associations. In your case, the easiest way would to create one seeder for courses and videos. (One note: I don't know how you are defining your primary and foreign key so I am making an assumption that the videos table has a field course_id.)
您可以使用 SequelizequeryInterface下拉到原始 SQL 以插入需要关联的模型实例。就您而言，最简单的方法是为课程和视频创建一个播种机。（注意：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, {});
}
};
回答by Eugene Manuilov
The bulkInsertmethod returns a promise that is resolved with an ID of the first inserted item. We can use this information to insert videos. It can look like this:
该bulkInsert方法返回一个使用第一个插入项的 ID 解析的承诺。我们可以使用此信息插入视频。它看起来像这样：
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, {} );
}
