0

我有以下相关模型

class Enrollment < ActiveRecord::Base
  has_many :addresses
end

class Address < ActiveRecord::Base
  belongs_to :address_type
end

目前我正在使用以下(我认为很难看)来过滤掉某种地址类型的注册地址。

class Enrollment < ActiveRecord::Base
  def local_address
    adds = []
    addresses.each do |add| 
      adds << add if add.address_type.name == 'Local'
    end
    adds.last
  end
end

有没有办法使用命名范围做同样的事情?

4

2 回答 2

0

一个通用的解决方案:

class Address < ActiveRecord::Base
  belongs_to :address_type
  named_scope :local, { :conditions => { :address_type => { :name => "Local" }}}
end

这允许您执行以下操作:

Enrollment.find(12).addresses.local  # Association extended with .local method
Address.local.all                    # Class methods extended with .local method

命名范围可以在您仅使用“本地”地址的所有情况下提供帮助。

于 2009-07-27T10:08:22.797 回答
0

参考以下stackoverflow帖子,我设法解决了我的命名范围查询

带有连接的 Rails named_scopes

基本上我需要在查询中加入

class Address < ActiveRecord::Base
  belongs_to :address_type
  named_scope :local, { 
    :joins => "INNER JOIN address_types ON address_types.id = addresses.address_type_id",
    :conditions => "address_types.name = 'Local'"
  }
end

如此有效,我可以将我的 Enrollment 的“local_address”方法重写为

clss Enrollment < ActiveRecord::Base
    def local_address
      addresses.local.last
    end
end
于 2009-07-28T02:57:23.297 回答