deep_merge.rb

require 'active_support/core_ext/class/attribute_accessors'
require 'active_support/core_ext/array'
require 'active_support/inflector'
require 'active_support/core_ext/class/inheritable_attributes'
require 'active_support/core_ext/duplicable'

class Hash #:nodoc:
  
  def deep_merge(other_hash)
    self.merge(other_hash) do |key, oldval, newval|
      oldval = oldval.to_hash if oldval.respond_to?(:to_hash)
      newval = newval.to_hash if newval.respond_to?(:to_hash)
      if oldval.is_a?(Hash) && newval.is_a?(Hash)
        oldval.deep_merge(newval)
      elsif oldval.is_a?(Array) && newval.is_a?(Array)
        oldval += newval
      else
        newval
      end
    end
  end
  
  def deep_merge!(other_hash)
    replace(deep_merge(other_hash))
  end
  
  def deep_symbolize_keys
    self.inject({}) { |result, (key, value)|
      value = value.deep_symbolize_keys if value.is_a?(Hash)
      result[(key.to_sym rescue key) || key] = value
      result
    }
  end
  
end