How do I convert a Ruby hash to XML?

ActiveSupport adds a to_xml method to Hash, so you can get pretty close to what you are looking for with this:

sudo gem install activesupport

require "active_support/core_ext"

my_hash = { :first_name => 'Joe', :last_name => 'Blow', :email => 'joe@example.com'}
my_hash.to_xml(:root => 'customer')

And end up with:

<?xml version="1.0" encoding="UTF-8"?>
<customer>  
   <last-name>Blow</last-name>  
   <first-name>Joe</first-name>  
   <email>joe@example.com</email>
</customer>

Note that the underscores are converted to dashes.