注释掉Nokogiri XML中的节点？

Question

Currently I'm removing curtain nodes form a document using:

doc.search('//xpathExpression').each do |node|
    node.remove
end

However, I really need to comment out the nodes rather than delete them. Is there a simple way to change the node type/comment out the current node?

Answer 1

To give credit where it's due, this is the method suggested by the original user in the comments above.

---

Do the following to comment out a given node or nodes based on an xpath:

1. Use the .xpath method to find the target nodes.
2. Prepend each node that's retuned with a copy of the node that's converted to a string inside a comment object.
3. Remove the original node.

For example, given:

#!/usr/bin/env ruby 

require "nokogiri"

xml = %{
<top>
  <child num="1"/>
  <child num="2"/>
</top>
}

doc = Nokogiri::XML(xml)

This code will comment out the second <child> based on the num="2" attribute.

doc.xpath("//top/child[@num='2']").each do |node|
  node.add_previous_sibling( Nokogiri::XML::Comment.new(doc, " #{node.to_s} ") ) 
  node.remove
end

After that process, doc.to_xml will be:

<?xml version="1.0"?>
<top>
  <child num="1"/>
  <!-- <child num="2"/> -->
</top>

Additional info:

• The comments produced by Nokogiri don't have white space between the <!-- and --> tokens and whatever content is added. The example above adds leading and trailing space. If that's not a concern, the node can be output with

   Nokogiri::XML::Comment.new(doc, node.to_s) 

• There doesn't seem to be a straightforward to do automatic pretty printing inside a comment. While there's likely a way around it, be ready to spend some time messing with it if you're concerned with the aesthetics.