Parsing an XML file with Nokogiri to determine the path (Ruby) - ruby

Question

My code is supposed to "guess" the path(s) that lies before the relevant text nodes in my XML file. Relevant in this case means: text nodes nested within the recurring product/person/something tag, but not text nodes that are used outside of it.
This code:
#doc, items = Nokogiri.XML(#file), []
path = []
#doc.traverse do |node|
if node.class.to_s == "Nokogiri::XML::Element"
is_path_element = false
node.children.each do |child|
is_path_element = true if child.class.to_s == "Nokogiri::XML::Element"
end
path.push(node.name) if is_path_element == true && !path.include?(node.name)
end
end
final_path = "/"+path.reverse.join("/")
works for simple XML files, for example:
<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0">
<channel>
<title>Some XML file title</title>
<description>Some XML file description</description>
<item>
<title>Some product title</title>
<brand>Some product brand</brand>
</item>
<item>
<title>Some product title</title>
<brand>Some product brand</brand>
</item>
</channel>
</rss>
puts final_path # => "/rss/channel/item"
But when it gets more complicated, how should I then approach the challenge? For example with this one:
<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0">
<channel>
<title>Some XML file title</title>
<description>Some XML file description</description>
<item>
<titles>
<title>Some product title</title>
</titles>
<brands>
<brand>Some product brand</brand>
</brands>
</item>
<item>
<titles>
<title>Some product title</title>
</titles>
<brands>
<brand>Some product brand</brand>
</brands>
</item>
</channel>
</rss>

Answer 1

If you are looking for a list of deepest "parent" paths in the XML, there is more than one way to view that.
Although I think your own code could be adjusted to achieve the same output, I was convinced the same thing could be achieved by using xpath. And my motivation is to get my XML skills unrusty (not used Nokogiri yet, but I will need to do so professionally soon). So here is how to get all parent paths that have just one child level beneath them, using xpath:
xml.xpath('//*[child::* and not(child::*/*)]').each { |node| puts node.path }
The output of this for your second example file is:
/rss/channel/item[1]/titles
/rss/channel/item[1]/brands
/rss/channel/item[2]/titles
/rss/channel/item[2]/brands
. . . if you took this list and gsub out the indexes, then make the array unique, then this looks a lot like the output of your loop . . .
paths = xml.xpath('//*[child::* and not(child::*/*)]').map { |node| node.path }
paths.map! { |path| path.gsub(/\[[0-9]+\]/,'') }.uniq!
=> ["/rss/channel/item/titles", "/rss/channel/item/brands"]
Or in one line:
paths = xml.xpath('//*[* and not(*/*)]').map { |node| node.path.gsub(/\[[0-9]+\]/,'') }.uniq
=> ["/rss/channel/item/titles", "/rss/channel/item/brands"]

Answer 2

I'm created a library to build xpath.
xpath = Jini.new
.add_path('parent')
.add_path('child')
.add_all('toys')
.add_attr('name', 'plane')
.to_s
puts xpath // -> /parent/child//toys[#name="plane"]