Ruby, Nokogiri: sort nodeset by attribute value

Question

I would like to sort a Nokigiri nodeset by the title value. Tried the following code, but sorting is not working :/ Any suggestions?

doc.xpath("//item").sort{|x,y| x.xpath('foo:attr[@name="title"]/@value').text <=> y.xpath('foot:attr[@name="title"]/@value').text }

XML example:

<item>
  <foo:attr name="title" value="a"/>
</item>
<item>
  <foot:attr name="title" value="c"/>
</item>
<item>
  <foor:attr name="title" value="b"/>
</item>

Output I am looking for: (nodeset)

<item>
  <foo:attr name="title" value="a"/>
</item>
<item>
  <foot:attr name="title" value="b"/>
</item>
<item>
  <foor:attr name="title" value="c"/>
</item>

Answer 1

If I understand your request, you want to remove them, then sort the array, then add them back:

xml = Nokogiri::XML.parse(data)
nodes = xml.root.css("item").remove
nodes.sort_by{ |node|
  node.css("attr")[0].attr("value"))
}.each{ |node|
  xml.root.add_child(node)
}