Question

ActiveRecord对象的XML序列化（to_xml）的默认行为将发出类似于XML Schema Instance属性的“type”和“nil”属性，但不在XML命名空间中设置。

例如，模型可能会生成如下输出：

<user>
  <username nil="true" />
  <first-name type="string">Name</first-name>
</user>

有没有让to_xml利用XML Schema Instance命名空间并为属性和值添加前缀？

使用上面的例子，我想产生以下内容：

<user xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" xmlns:xs="http://www.w3.org/1999/XMLSchema">
  <username xsi:nil="true" />
  <first-name xsi:type="xs:string">Name</first-name>
</user>

Answer 1

我有类似的要求，并选择了子类:: Builder :: XmlMarkup：

require 'builder/xmlmarkup'

class MyXmlMarkup < ::Builder::XmlMarkup
  def tag!(sym, *args, &block)
    if @level == 0 # Root element
      args << {"xmlns" => "http://my_company.com/api/schemas/xml",
               "xmlns:xsi" => "http://www.w3.org/2001/XMLSchema-instance"}
    end

    if args[:nil] = true
      args << {"xsi:nil" => true}
    end

    super(sym, *args, &block)
  end
end

然后你可以用它：

foo.to_xml(builder: MyXmlMarkup.new(indent: 2))

Answer 2

我碰到了类似的东西，但在Hash上调用#to_xml时，而不是在AR实例上调用#to_xml。

我想出了这个帮手：

  #
  # Returns a new Builder::XmlMarkup that'll handle API's to_xml needs
  # Usually you don't need to construct a builder, as to_xml will create one
  # however we need some things modified (adding a namespace, XSD-nillable-compliant-nils
  # and to_xml is too braindead to allow us to alter such behaviors externally
  #
  def api_new_xml_builder
    builder = Builder::XmlMarkup.new(:indent => 2)
    class << builder
      def method_missing(*args, &block)
        @api_seen ||= 0
        @api_seen += 1
        if @api_seen == 1
          # Root element. Needs some decoration
          args[1] ||= {}
          args[1]["xmlns"] = "http://my_company.com/api/schemas/xml"
          args[1]["xmlns:xsi"] = "http://www.w3.org/2001/XMLSchema-instance"
        end
        if args[2].is_a?(Hash) && args[2][:nil] == true
          args[2]["xsi:nil"] = true
        end
        super(*args, &block)
      end
    end
    builder
  end

然后像这样使用：

builder = api_new_xml_builder
foo.to_xml(:builder => builder)

请注意，我选择保留现有的nil =和type =属性，并添加我自己的xsi-prefixed nil，但是替换它们是微不足道的。

获取ActiveRecord（Rails）to_xml以使用xsi：nil和xsi：type而不是nil和type

2 个答案: