不同模型的多个哈希数组上的rails 2和ruby 1.9.2 sort_by

Question

我正在对来自两个不同模型的具有多个哈希的数组对象进行排序，我需要对另一个模型具有不同名称的字段进行排序

数组对象跟随

 [#<TechpackAttachment id: 16, company_id: 1, version_id: 38, techpack_identifier: "5bb55062-db53-11e3-abae-d43d7e129fac", body: nil, attachment_description: nil, document_file_name: "sandle.jpg", document_content_type: "image/jpeg", document_file_size: 5717, document_updated_at: "2014-05-22 10:15:36", creator_id: 1, updater_id: 1, created_at: "2014-05-22 10:15:36", updated_at: "2014-05-22 10:15:36", is_primary_image: false>, #<SampleImage id: 13, company_id: 1, vendor_id: 1, sample_id: 4, body: nil, attachment_description: nil, private_to_vendor: 0, image_file_name: "53.png", image_content_type: "image/png", image_file_size: 318585, image_updated_at: "2014-02-19 13:24:05", creator_id: 1, updater_id: 1, created_at: "2014-02-19 13:24:05", updated_at: "2014-02-19 13:24:05", is_primary_image: false>  ] 

在上述对象中，我需要按在SampleImage模型中具有不同名称的document_file_name进行排序，即image_file_name。

我所做的是

    @rec = @rec.sort_by {|i| i.document_file_name.nil? ? i.image_file_name : i.document_file_name }    

给我错误

  undefined method `document_file_name' for #<SampleImage:0xa9cb9298>

编辑

我仅举两个模型为例，但数组对象中有10个模型，其中一些模型的哈希值中包含文档，其他模型中的图像中包含图像。

Answer 1

您可以检测对象是否响应document_file_name方法：

@rec = @rec.sort_by do |i|
  if i.respond_to?(:document_file_name)
    i.document_file_name
  else
    i.image_file_name
  end
end

Answer 2

我认为这会有所帮助。

@rac = [#<TechpackAttachment id: 16, company_id: 1, version_id: 38, techpack_identifier: "5bb55062-db53-11e3-abae-d43d7e129fac", body: nil, attachment_description: nil, document_file_name: "sandle.jpg", document_content_type: "image/jpeg", document_file_size: 5717, document_updated_at: "2014-05-22 10:15:36", creator_id: 1, updater_id: 1, created_at: "2014-05-22 10:15:36", updated_at: "2014-05-22 10:15:36", is_primary_image: false>, #<SampleImage id: 13, company_id: 1, vendor_id: 1, sample_id: 4, body: nil, attachment_description: nil, private_to_vendor: 0, image_file_name: "53.png", image_content_type: "image/png", image_file_size: 318585, image_updated_at: "2014-02-19 13:24:05", creator_id: 1, updater_id: 1, created_at: "2014-02-19 13:24:05", updated_at: "2014-02-19 13:24:05", is_primary_image: false>  ]  

@rec = @rec.sort_by { |i| i.kind_of?(TechpackAttachment) ? i.document_file_name : i.image_file_name }