范围和关联不起作用

Question

我正在尝试 return 记录关联是否存在：

我尝试了这些示波器：

class Booking < ActiveRecord::Base
  has_one :availability

  scope :with_availability, -> {where{availability.not_eq nil}}
  scope :without_availability, -> {where{availability.eq nil}}
end

Answer 1

改用实例方法

def with_availability
  availability.present?
end

def without_availability
  availability.blank?
end

Answer 2

我知道有更好的方法，但这也应该有效：

class Booking < ActiveRecord::Base
  has_one :availability

  scope :with_availability, -> {where(id: Availability.pluck(:booking_id))}
  scope :without_availability, -> {where.not(id: Availability.pluck(:booking_id))}
end

我也尝试通过下面的 link 重现解决方案，但我没能做到（但这可能会有帮助）：

Rails - has_one relationship : scopes for associated and non-associated objects

Answer 3

试试这个：

class Booking < ActiveRecord::Base
  has_one :availability

  scope :with_availability, -> { joins{availability} }
  scope :without_availability, -> { joins{availability.outer}.where{availability.id.eq nil} }
end