在 ActiveRecord 中使用类似的范围

Question

我在 ActiveRecord 中使用类似范围时遇到问题。我有 3 个模型：

人：

class Person < ActiveRecord::Base
  has_many :survey_packs

  def self.by_first_name(text)
    where(first_name: text)
  end
end

调查包：

class SurveyPack < ActiveRecord::Base
  has_many :survey_instances, inverse_of: :survey_pack
  belongs_to :person
end

和调查实例：

class SurveyInstance < ActiveRecord::Base
  belongs_to :survey_pack, inverse_of: :survey_instances
  belongs_to :student, class_name: 'Person', foreign_key: :person_id

  scope :teacher_full_name, ->(text) { SurveyInstance.joins(:person).merge(Person.by_first_name(text)) }
  scope :student_full_name, ->(text) { SurveyInstance.joins(:student).merge(Person.by_first_name(text)) }
end

问题是我无法将这些范围连接在一起：

  scope :teacher_full_name, ->(text) { SurveyInstance.joins(:person).merge(Person.by_first_name(text)) }
  scope :student_full_name, ->(text) { SurveyInstance.joins(:student).merge(Person.by_first_name(text)) }

例如，我有一个调查实例，学生姓名为：“学生”，教师姓名为：“教师”：

SurveyInstance.teacher_full_name('Teacher') #this will work
SurveyInstance.student_full_name('Student') #this will also work
SurveyInstance.teacher_full_name('Teacher').student_full_name('Student') #this will not work...

我不知道如何解决这个问题...

Answer 1

不确定这是否有效，但逻辑类似于：

class SurveyInstance < ActiveRecord::Base
  belongs_to :survey_pack, inverse_of: :survey_instances
  belongs_to :student, class_name: 'Person', foreign_key: :person_id

  scope :full_name, ->(type, text) { SurveyInstance.joins(type).merge(Person.by_first_name(text)) }
end

提取关联，以便符号通过作用域调用传递。

调用作用域：

SurveyInstance.full_name(:person, 'Teacher')
SurveyInstance.full_name(:student, 'Student')