Question

我使用Rails 5，我想与其他查询做has_and_belongs_to_many关系。它不是合并两个查询，而是不相同。其实我想干净利落。

branches
-----------------------------------
id
name:string
active:boolean
..

course_contents
-----------------------------------
id
title:string
show_all_branches:boolean
active:boolean
..

branches_course_contents
-----------------------------
branch_id
course_content_id


class Branch < ApplicationRecord
  has_and_belongs_to_many :course_contents
  scope :active, -> { where(active: true) }
end

class CourseContent < ApplicationRecord
  has_and_belongs_to_many :branches
  scope :active, -> { where(active: true) }
  scope :show_all_branches, -> { where(show_all_branches: true) }
end

我怎样才能干净？

@branch.course_contents.active + CourseContent.show_all_branches

我想用rails编写这个sql输出。那个sql命令对我来说很好。

select *, 
  (select branch_id 
   from branches_course_contents 
   where course_content_id=course_contents.id and branch_id=2) as Sube 
from course_contents 
where 
  (select branch_id
    from branches_course_contents 
    where course_content_id=course_contents.id and branch_id=2)=2 
   or show_all_branches=true) 
  and content_type=0

Answer 1

试试这个：

@branch.course_contents.active.merge(CourseContent.show_all_branches)

Rails has_and_belongs_to_many与其他查询的关联

1 个答案: