Ruby/Nokogiri xmlns and other extensions via xpath - ruby

Question

In the code below I'm trying to pull '90000' element using an xpath, but Nokogiri returns nil
<?xml version="1.0" encoding="UTF-8"?>
<rspec xmlns="URL1"
xmlns:add="URL2">
<node>
<price add:cars="90000"/>
</node>
</rspec>
I try the command:
puts root.xpath("//add:cars", "add" => "URL2")
but it doesn't seem to work.
Could you please help me, I'm new at Ruby and I have searched a lot but I couldn't find anything.

Answer 1

add:cars is an attribute of the price element, not an element itself. The syntax you want is:
root.xpath("//xmlns:price/#add:cars")
or possibly even just
root.xpath("//#add:cars")
if you want the add:cars attributes of all elements.
Note that since the namespaces are declared on the root, Nokogiri registers them automatically so you don’t need to include the mappings in your call to xpath (you will need to include them if your document is more complex with namespaces being declared on non-root elements). Also the default namespace is registered with the prefix xmlns, so you can use that in your XPath.

Answer 2

Here is one way to do this :
require 'nokogiri'
#doc = Nokogiri::XML.parse <<-eotl
<?xml version="1.0" encoding="UTF-8"?>
<rspec xmlns="URL1"
xmlns:add="URL2">
<node>
<price add:cars="90000"/>
</node>
</rspec>
eotl
#doc.remove_namespaces!
#doc.at_xpath('//price/#cars').text
# => "90000"
or(if you want to keep namespaces as it is, then use below)
#doc.at_xpath('//xmlns:price/#add:cars').text
# => "90000"
Read this tutorial : Searching an HTML / XML Document

Answer 3

I'm a fan of letting Nokogiri use CSS when dealing with namespaces:
require 'nokogiri'
xml = '<?xml version="1.0" encoding="UTF-8"?>
<rspec xmlns="URL1"
xmlns:add="URL2">
<node>
<price add:cars="90000"/>
</node>
</rspec>
'
doc = Nokogiri::XML(xml)
doc.at('price', 'add')['add:cars']
# => "90000"