Wrapping with Nokogiri - ruby

Question

I apologize if this has been answered, but I can't find the correct way to get this working. I'm using Nokogiri to modify SVG diagrams that are generated through an application and I hit a bit of a snag. The code I'm working with looks something like this:
<svg>
<g id="1">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="2">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="3">
<text>lorem</text>
<text>ipsum</text>
</g>
<svg>
I'd like to have this appended to every document as it is analyzed by the script:
<svg>
<g id="scale" transform="scale(1.0)">
<g id="1">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="2">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="3">
<text>lorem</text>
<text>ipsum</text>
</g>
</g>
<svg>
I've tried using methods such as before and after but it won't work correctly in this situation. Ideally I'd just wrap the entirety of the nodeset with wrap, but I can't figure out how to get it to work across all sets rather than on every nodeset. Any guidance would be much appreciated.
Thanks!

Answer 1

Here's how I'd do it:
require 'nokogiri'
doc = Nokogiri::XML(<<EOT)
<svg>
<g id="1">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="2">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="3">
<text>lorem</text>
<text>ipsum</text>
</g>
</svg>
EOT
svg = doc.at('svg')
svg.children = '<g id="scale" transform="scale(1.0)">' + svg.children.to_xml + '</g>'
puts svg.to_xml
Running that outputs:
<svg>
<g id="scale" transform="scale(1.0)">
<g id="1">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="2">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="3">
<text>lorem</text>
<text>ipsum</text>
</g>
</g>
</svg>
Nokogiri nicely lets us define nodes as strings, and coerces them to XML::Node objects. Give it a string containing XML and it'll convert it into a NodeSet, so we can cleanly and clearly manipulate the XML DOM without having to write u-gly code.

Answer 2

doc = Nokogiri.XML( raw_svg )
wrapper_g = doc.create_element('g', 'id' => "scale", 'transform' => "scale(1.0)")
doc.xpath('/svg/g').each {|elem| wrapper_g << elem }
doc.root << wrapper_g
Optional - remove empty text nodes:
doc.xpath('//text()').each {|t| t.text =~ /\A\s*\z/ and t.remove }

Answer 3

The cheat sheet might help.
require 'nokogiri'
doc = Nokogiri::XML(%Q{
<svg>
<g id="1">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="2">
<text>lorem</text>
<text>ipsum</text>
</g>
<g id="3">
<text>lorem</text>
<text>ipsum</text>
</g>
</svg>
})
svg = doc.xpath('//svg')[0]
wrapper = doc.create_element('g', 'id' => 'scale', 'transform' => 'scale(1.0)')
wrapper.children = svg.children
svg.add_child wrapper
puts doc
Note that you missed the slash at the closing svg tag.