ruby-on-rails - Ruby has_many 关联模型查询与 Postgres 数据库 (Rails 5)

Question

我有模型，医师，有_很多患者。尝试编写一个查询，该查询只会导致 Physicians that have all cured patients。因此，医生的每个患者都必须具有属性“is_cured: true”(或者至少对于所有医生患者而言不是 nil)。

到目前为止，医生只是在治愈一名患者而非所有患者时出现:

@physicians = Physician.includes(:patients)
.where.not(患者: { id: nil })
.where(患者: { is_cured: true })

模型:

class Physician < ApplicationRecord
  has_many :patients
  has_many :recommendations, through: :patients
end

class Patient < ApplicationRecord
  belongs_to :physician
  belongs_to :recommendation
end

class Recommendation < ApplicationRecord
  has_many :patients
  has_many :physicians, through: :patients
end

感谢您提供的任何帮助!

Answer 1

# Fetches physicians who have at-least one uncured patient
phys_with_uncured_patients = Physician.joins(:patients).where(patients: { is_cured: false })

#Fetches physicians who have at-least one patient and all are cured.
Physician.joins(:patients).where.not(id: phys_with_uncured_patients)