如何在 NodeJS Sequelize 中通过查询对组进行计数

在 Rails 中，我可以执行简单的 ORM 查询来获取模型的点赞数：

    @records = Model
        .select( 'model.*' )
        .select( 'count(likes.*) as likes_count' )
        .joins( 'LEFT JOIN likes ON model.id = likes.model_id' )
        .group( 'model.id' )

这会生成查询：

SELECT  models.*, count(likes.*) as likes_count
FROM "models" JOIN likes ON models.id = likes.model_id
GROUP BY models.id

在 Node Sequelize 中，任何尝试执行类似操作都会失败：

return Model.findAll({
    group: [ '"Model".id' ],
    attributes: ['id', [Sequelize.fn('count', Sequelize.col('"Likes".id')), 'likes_count']],
    include: [{ attributes: [], model: Like }],
});

这会生成查询：

SELECT
    Model.id,
    count(Likes.id) AS likes_count,
    Likes.id AS Likes.id           # Bad!
FROM Models AS Model
LEFT OUTER JOIN Likes
    AS Likes
    ON Model.id = Likes.model_id
GROUP BY Model.id;

这会产生错误：

column "Likes.id" must appear in the GROUP BY clause or be used in an aggregate function

它错误地选择了 likes.id，我不知道为什么，也不知道如何摆脱它。

这是 github 问题的续集 https://github.com/sequelize/sequelize/issues/222#issuecomment-31682253看起来完全像你的情况：

User.findAll({
  attributes: ['User.*', 'Post.*', [sequelize.fn('COUNT', 'Post.id'), 'PostCount']],
  include: [Post]
});