migpo.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

require 'nokogiri'

path = ARGV.shift

doc = Nokogiri::XML(File.open(path))
doc.xpath("/database/object").each do |object|
  o = object.clone
  o.children.each do |element|
    if element.attribute("name")&.value == "sourcename"
      entity = element.child.text
      o.add_child("<attribute name=\"migrationpolicyclassname\" type=\"string\">#{entity}To#{entity}MigrationPolicy</attribute>")
    end
  end
  
  object.replace(o)
end

doc.write_xml_to(File.open(File.basename(path), "w"))