ruby-on-rails - 如何通过特定字段对 has_many 进行排序

Question

我有 3 个型号:member , team , 和 team_enrollment .结构如下:

class Member < ApplicationRecord
  has_many :team_enrollments    
  has_many :teams, -> {order 'team_enrollments.termination_date DESC NULLS LAST'}, through: :team_enrollments
end

class TeamEnrollment < ApplicationRecord
  belongs_to :team
  belongs_to :member
end

class Team < ApplicationRecord
    has_many :team_enrollments
    has_many :members, through: :team_enrollments
end

我试图做到这样，当有人从成员那里调用团队时(所以 Member.first.teams)，团队按属性 termination_date 降序排列。存在于 team_enrollments 上 table 。我也想要它，如果 termination_date是 nil 它在订单的末尾。我以为 has_many :teams, -> {order 'team_enrollments.termination_date DESC NULLS LAST'}, through: :team_enrollments上面的行会起作用，但不会。似乎对订单没有影响。我该如何改变？

顺便说一下，我在本地和生产中使用 postgres。

Answer 1

我会尝试使用 default_scope而不是尝试将 order 子句放在关联中

class Member < ApplicationRecord
  has_many :team_enrollments    
  has_many :teams, through: :team_enrollments
end

class TeamEnrollment < ApplicationRecord
  belongs_to :team
  belongs_to :member
  default_scope {order 'termination_date DESC NULLS LAST'}
end

class Team < ApplicationRecord
   has_many :team_enrollments
   has_many :members, through: :team_enrollments
end