What can I use to generate a local XML file?

I have a project that I am working on and I do not know much about Rails or Ruby.

I need to generate an XML file from user input. Can some direct me to any resource that can show me how to do this pretty quickly and easily?

The Nokogiri gem has a nice interface for creating XML from scratch. It's powerful while still easy to use. It's my preference:

require 'nokogiri'
builder = Nokogiri::XML::Builder.new do |xml|
  xml.root {
    xml.products {
      xml.widget {
        xml.id_ "10"
        xml.name "Awesome widget"
      }
    }
  }
end
puts builder.to_xml

Will output:

<?xml version="1.0"?>
<root>
  <products>
    <widget>
      <id>10</id>
      <name>Awesome widget</name>
    </widget>
  </products>
</root>

Also, Ox does this too. Here's a sample from the documenation:

require 'ox'

doc = Ox::Document.new(:version => '1.0')

top = Ox::Element.new('top')
top[:name] = 'sample'
doc << top

mid = Ox::Element.new('middle')
mid[:name] = 'second'
top << mid

bot = Ox::Element.new('bottom')
bot[:name] = 'third'
mid << bot

xml = Ox.dump(doc)

# xml =
# <top name="sample">
#   <middle name="second">
#     <bottom name="third"/>
#   </middle>
# </top>