Ruby on Rails：嵌套命名作用域

Question

有什么方法可以將命名作用域嵌套在不同模型中？

例：

class Company
  has_many :employees
  named_scope :with_employees, :include => :employees
end
class Employee
  belongs_to :company
  belongs_to :spouse
  named_scope :with_spouse, :include => :spouse
end
class Spouse
  has_one :employee
end

在包括這樣的員工和配偶的情況下，有什么好辦法讓我找到公司嗎？
Company.with_employees.with_spouse.find(1)
還是我有必要在Company中定義另一個named_scope：
:with_employees_and_spouse, :include => {:employees => :spouse}

在這個人為的示例中，還算不錯，但是嵌套在我的應用程序中更深入了，如果我不必添加un-DRY代碼來在嵌套的每個級別重新定義包含，我都希望這樣做。

Answer 1

您可以使用默認范圍

class Company
  default_scope :include => :employees
  has_many :employees
end

class Employee
  default_scope :include => :spouse
  belongs_to :company
  belongs_to :spouse
end

class Spouse
  has_one :employee
end

然后這應該工作。 我還沒有測試過。

Company.find(1)          # includes => [:employee => :spouse]

Answer 2

嘗試這個

Company.with_employees.merge( Employees.with_spouse)

Answer 3

您需要始終定義所有條件。 但是您可以定義一些方法來組合一些named_scope

class Company
  has_many :employees
  named_scope :with_employees, :include => :employees
  named_scope :limit, :lambda{|l| :limit => l }

  def with_employees_with_spouse
    with_employees.with_spouse
  end

  def with_employees_with_spouse_and_limit_by(limit)
    with_employees_with_spouse.limit(limit)
  end

end
class Employee
  belongs_to :company
  belongs_to :spouse
  named_scope :with_spouse, :include => :spouse
end
class Spouse
  has_one :employee
end