打印顶部没有 XML 标题行的 XML 文档 [英] Print an XML document without the XML header line at the top

问题描述

我只是想找出如何使用 Nokogiri::XML::Document 或 Nokogiri::XML::DocumentFragment 到 to_xml.

I am just trying to find out how to to a to_xml with a Nokogiri::XML::Document or a Nokogiri::XML::DocumentFragment.

或者，我想在 Nokogiri::XML::DocumentFragment 上使用 xPath.我无法确定如何做到这一点，但是我成功解析了 Nokogiri::XML::Document.

Alternatively, I would like to use xPath on a Nokogiri::XML::DocumentFragment. I was unable to ascertain how to do that, however I am successfully parsing a Nokogiri::XML::Document.

我稍后将解析和修改的 DocumentFragment 包含到另一段 XML 中，但我真的被我认为是一些非常简单的事情所困扰.

I am later including a parsed and modified DocumentFragment into another piece of XML, but I'm really getting bitten on what I thought would be some really simple things.

就像尝试在 doc 或 docfrag 上执行 to_xml 一样，而不包括顶部的那行 xml.为什么这么难?

Like trying to do a to_xml on a doc or docfrag, and NOT INCLUDING that xml line at the top. Why so hard?

推荐答案

获取 Document 的 XML 的最简单方法，无需前导PI"(处理指令) 是在根元素上调用 to_s 而不是文档本身:

The simplest way to get the XML for a Document without the leading "PI" (processing instruction) is to call to_s on the root element instead of the document itself:

require 'nokogiri'
doc = Nokogiri.XML('<hello world="true" />')

puts doc
#=> <?xml version="1.0"?>
#=> <hello world="true"/>

puts doc.root
#=> <hello world="true"/>

在文档或构建器级别执行此操作的正确"方法是使用 SaveOptions:

The 'correct' way to do it at the document or builder level, though, is to use SaveOptions:

formatted_no_decl = Nokogiri::XML::Node::SaveOptions::FORMAT +
                    Nokogiri::XML::Node::SaveOptions::NO_DECLARATION

puts doc.to_xml( save_with:formatted_no_decl )
#=> <hello world="true"/>

# Making your code shorter, but horribly confusing for future readers
puts doc.to_xml save_with:3
#=> <hello world="true"/>

 

请注意，DocumentFragment不会自动执行包括这个 PI:

Note that DocumentFragments do not automatically include this PI:

frag = Nokogiri::XML::DocumentFragment.parse('<hello world="true" />')
puts frag
#=> <hello world="true"/>

如果您在片段输出中看到一个 PI，则意味着在您解析它时它就在那里.

If you are seeing a PI in your fragment output, it means it was there when you parsed it.

xml = '<?xml version="1.0"?><hello world="true" />'
frag = Nokogiri::XML::DocumentFragment.parse(xml)
puts frag
#=> <?xml version="1.0"?><hello world="true"/>

如果是这样，并且您想摆脱任何 PI，您可以这样做 应该使用一点 XPath 即可:

If so, and you want to get rid of any PIs, you can do so should be able to do so with a little XPath:

frag.xpath('//processing-instruction()').remove
puts frag

...除了这似乎不起作用由于DocumentFragments 中 XPath 的奇怪之处.要解决这些错误，请改为执行此操作:

…except that this does not appear to work due to oddness with XPath in DocumentFragments. To work around these bugs do this instead:

# To remove only PIs at the root level of the fragment
frag.xpath('processing-instruction()').remove
puts frag
#=> <hello world="true"/>

# Alternatively, to remove all PIs everywhere, including inside child nodes
frag.xpath('processing-instruction()|.//processing-instruction()').remove

 

如果您有 Builder 对象，请执行以下任一操作:

If you have a Builder object, do either of:

builder = Nokogiri::XML::Builder.new{ |xml| xml.hello(world:"true") }

puts builder.to_xml
#=> <?xml version="1.0"?>
#=> <hello world="true"/>

puts builder.doc.root.to_xml
#=> <hello world="true"/>

formatted_no_decl = Nokogiri::XML::Node::SaveOptions::FORMAT +
                    Nokogiri::XML::Node::SaveOptions::NO_DECLARATION

puts builder.to_xml save_with:formatted_no_decl
#=> <hello world="true"/>

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