Flatten hashes recursively

flatten_with_path.rb

# From http://stackoverflow.com/questions/16497719/flatten-a-nested-hash-in-ruby-on-rails

module Enumerable
  def flatten_with_path(parent_prefix = nil)
    res = {}

    self.each_with_index do |elem, i|
      if elem.is_a?(Array)
        k, v = elem
      else
        k, v = i, elem
      end

      # assign key name for result hash
      key = parent_prefix ? "#{parent_prefix}.#{k}" : k

      if v.is_a? Enumerable
        # recursive call to flatten child elements
        res.merge!(v.flatten_with_path(key))
      else
        res[key] = v
      end
    end

    res
  end
end