Convert Ruby hash keys to dotted form like backbone-deep-model

hflatten.rb

class Hash
  def hflatten(path=[])
    self.inject({}) do |a,(k,v)|
      if v.is_a? Hash
        # Recurse
        a.merge(v.hflatten(path.dup << k))
      else
        # Base case
        a[(path.dup << k).join('.')] = v; a
      end
    end
  end
end

test_hflatten.rb

require 'hflatten'
require 'test/unit'

class TestHflatten < Test::Unit::TestCase
  def test_hflatten
    h = {
      'user' => {
        'name' => {
          'first' => 'John',
          'last' => 'Doe'
        }
      },
      'greeting' => 'Howdy!'
    }

    expected = {
      'user.name.first' => 'John',
      'user.name.last'  => 'Doe',
      'greeting'        => 'Howdy!'
    }

    assert_equal(expected, h.hflatten)
  end
end