ruby 在 rails 上：搜索关联

Question

我的理解有点问题：

我有 Channel 和 Lecturer，其中 Channel :has_and_belongs_to_many :lecturers.

我想获取 Lecturer.id 为 lect.id 的所有频道。

2.3.0 :235 >   Channel.where(:lecturers => { :id => 2 })
  Channel Load (0.1ms)  SELECT "channels".* FROM "channels"  WHERE "lecturers"."id" = 2
SQLite3::SQLException: no such column: lecturers.id: SELECT "channels".* FROM "channels"  WHERE "lecturers"."id" = 2
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: lecturers.id: SELECT "channels".* FROM "channels"  WHERE "lecturers"."id" = 2

这行不通，我觉得我不明白核心概念，因为我可以做到

2.3.0 :231 > Channel.first.lecturer  
=> #<Lecturer id: 2, name: "Albert Einstein">

我错过了什么？

Answer 1

您需要连接表来执行此查询。参见 the docs

Channel.joins(:lecturer).where(lecturers: {id: lect.id})

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