Lib Xml Ruby :Error `parse': undefined method `read' for "file.xml":String (NoMethodError)

require 'xml/libxml'
require 'libxml/document'
$release_date
doc=LibXML::XML::Parser.io(file.xml).parse 
doc.root.each_element('//ABCD/xyz/') do |elem|
    elem.each_element do |node|             
        node.each_element do |child|
           if child.content=="ABCD"
               $release_date=node['date']
           else 
               if node['type']=="Original"
                   $release_date=node['date']
               end
           end  
        end    
    end 
end
puts "Release date : #{$release_date}"

This is the code that I've written to extract a particular date from an XML file according to my requirements. I've used lib xml library but am getting the following errors:

`parse': undefined method `read' for "file.xml":String (NoMethodError)

As per libxml documentation, to parse a file:

LibXML::XML::Parser.file('file.xml').parse

or

LibXML::Parser.io(File.open('file.xml')).parse

Also, each_element doesn’t take any parameter. If you want to do an XPath query, have a look at find:

require 'xml'
doc = LibXML::XML::Parser.file("/tmp/test.xml").parse 
nodes = doc.find('//test')
nodes.each do |n|
  puts n.content
end