[英]Find instances associated with multiple (all) instances from other model in Sequelize
简化的Sequelize模型示例:
Post.belongsToMany(Tag)
Tag.belongsToMany(Post)
如何findAll
与一组标签中的所有标签相关联的所有帖子?
示例数据集:
post
{ id: 1 }
{ id: 2 }
tag
{ id: 10 }
{ id: 11 }
post_tag
{ post_id: 1, tag_id: 10 }
{ post_id: 2, tag_id: 10 }
{ post_id: 2, tag_id: 11 }
因此,如果所涉及的标签是10和11 ,则查询应返回Post 2,因为它与两个标签都关联,但返回Post 1,因为它没有与所有标签都关联。 (标签的数量当然可以超过两个)
可能有一种在一个Sequelize findAll
请求中构造此请求的方法,但是我不得不使用原始SQL来完成您的任务。 这是两种方法:
Post.findAll
及其结果 查找包含所有标签的post_ids
const postIds = await db.query(`
SELECT post_id FROM (
SELECT post_id, COUNT(*) AS counter
FROM post_tag
GROUP BY post_id
) AS tbl
WHERE counter = (SELECT count(*) as COUNT from tags);;
`, {type: db.QueryTypes.SELECT})
查找postIds
数组中存在的postIds
const posts = await Post.findAll({
where: {
id: {
$in: postIds.map(x => x.post_id)
}
}
});
const posts = await db.query(`
SELECT *
FROM posts
WHERE id IN (
SELECT post_id FROM (
SELECT post_id, COUNT(*) AS counter
FROM post_tag
GROUP BY post_id
) AS tbl
WHERE counter = (SELECT count(*) as COUNT from tags)
)
`, {type: db.QueryTypes.SELECT});
(以前,我添加了这两种方法,因为我更喜欢应用程序代码中的原始SQL)
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