Question

我有3个型号。 Users，Groups，Employees这三者中的所有人都有很多人。

用户有很多小组
群组有很多用户
团体有很多员工
员工有很多小组

所以我创建了两个新模型：

Departments（处理Users和Groups之间的多对多
Employments（处理Groups和Employees之间的多对多 class Employment < ActiveRecord::Base belongs_to :group belongs_to :employee end）

我相信我在纸上有这个正确但我无法正确编码，因为我是新手。因此，数据提取似乎不正确。

这就是我所拥有的：就业：

class Department < ActiveRecord::Base
  belongs_to  :group
  belongs_to  :user
end

系：

class User < ActiveRecord::Base
  has_many :departments
  has_many :groups, :through=>:departments

  has_many :employees, :through=>:departments, :source => :group
end

用户：

class Group < ActiveRecord::Base
  has_many :departments #new
  has_many :users, :through => :departments #new

  has_many    :employments
  has_many    :employees, :through => :employments
end

组：

class Employee < ActiveRecord::Base
  has_many    :employments
  has_many    :groups, :through => :employments
end

员工：

total employees

我认为我遇到的最大问题是弄清楚如何为用户获取select * from employees where id in (select employee_id from employments where group_id in (select group_id from departments where user_id = 4))。在sql中，它可以使用此查询：

{{1}}

Answer 1

这可能对你有用......

class User < ActiveRecord::Base
  has_many :departments
  has_many :groups, :through=>:departments **, :include => :employee** 

  has_many :employees, :through=>:departments, :source => :group
end


User.find(4).groups.collect { |c| c.employee.size }

帮助Rails ActiveRecord管理查询

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