动态`named_scope`取决于某些标准

Question

亲爱的,我有一个Student,我已经指定一些模式name_scope在里面,例如from_program,from_year,from_school,has_status,from_course,等...

无论如何,我可以named_scope在运行时根据某些标准动态地将不同的链接在一起吗？

例如,如果访问数据的用户是从金融,我想能够链from_school和has_status仅在一起.如果用户是讲师,我希望能够给链from_course,from_school在一起,等等...

我应该用named_scope吗？或者我应该回到指定条件的旧方法？

提前感谢您的建议!=)顺便说一句,我正在使用rails 2.3

Answer 1

我不确定,如果我理解,但我认为你可以这样做:

class Student

  named_scope from_program, lambda{|program| :conditions => {:program => program}}
  named_scope from_year, lambda{|year| :conditions => {:year => year}}
  named_scope has_status, lambda{|status| :conditions => {:status => status}}

  def self.from_finance(school, status)
    self.from_school(school).has_status(status)
  end

end

或者更一般

def self.get_students(params)
  scope = self
  [:program, :year, :school, :course].each do |s|
    scope = scope.send("from_#{s}", params[s]) if params[s].present?
  end
  scope = scope.has_status(params[:status]) if params[:status].present?
  scope
end