ruby-on-rails - 使用to_json时如何访问 ':has_many :though'连接表数据？

Question

我有三个模型(这里简化):

class Child < ActiveRecord::Base
  has_many    :childviews, :dependent => :nullify
  has_many    :observations, :through => :childviews  
end
class Childview < ActiveRecord::Base
  belongs_to  :observation
  belongs_to  :child
end
class Observation < ActiveRecord::Base
  has_many    :childviews, :dependent => :nullify
  has_many    :children, :through => :childviews
end

我正在使用 Rails 的 to_json 方法将其发送到一些 JavaScript，如下所示:

render :layout => false , :json => @child.to_json(
  :include => {
    :observations => {
      :include => :photos, 
      :methods => [:key, :title, :subtitle]
    }
  },
  :except => [:password]
)

这非常有效。观察结果可以“通过”连接表( subview )很好地检索。

然而，我还想获取位于 childviews 连接表中的数据；特别是“needs_edit”的值。

我不知道如何在 to_json 调用中获取这些数据。

谁能帮帮我？非常感谢。

qryss

Answer 1

不确定，但这不应该有效吗？

@child.to_json(
  :include => {
    :observations => {
      :include => :photos, 
      :methods => [:key, :title, :subtitle]
    },
    :childviews => { :only => :needs_edit }
  }, 
  :except => [:password]
)

编辑:这也可能有效，因为 childviews belongs_to the overvation:

@child.to_json(
  :include => {
    :observations => {
      :include => { :photos, :childviews => { :only => :needs_edit } } 
      :methods => [:key, :title, :subtitle]
    }
  }, 
  :except => [:password]
)