Ruby on Rails：嵌套命名范围

Question

有没有办法将不同模型的命名范围嵌套在一起？

示例：

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

有什么好方法让我找到一家公司，同时包括员工和配偶，如下所示：
Company.with_employees.with_spouse.find(1)
或者我是否有必要在公司中定义另一个named_scope：
:with_employees_and_spouse, :include =>; {：员工=> :spouse}

在这个人为的示例中，这还不错，但是我的应用程序中的嵌套更深，如果我不必添加在每个位置重新定义包含的非 DRY 代码，我会喜欢它嵌套的级别。

Answer 1

您可以使用默认范围，

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

然后这应该可以工作。不过我还没有测试过。

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

Answer 2

您需要始终定义所有条件。但是你可以定义一些方法来组合一些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

Answer 3

试试这个

Company.with_employees.merge( Employees.with_spouse)