From: Ross Bamford <rossrt@...>
Date: 2006-09-28T06:57:19+09:00
Subject: Re: Accessing Nested Hashes Directly

On Thu, 2006-09-28 at 02:05 +0900, atraver@gmail.com wrote:
> Thanks for all the responses.
> 
> Here is the method I ended up with after looking over everything, just
> in case this topic is searched for in the future:
> 
>   def get_value(object, *path)
>     for item in path
>       break unless object
>       object = object ? object[item.to_s] : nil
>     end
> 
>     return object.kind_of?(String) ? object.strip : object
>   end
> 
> This might be a little more verbose than some of the solutions (also,
> Ross, your "inject" solution didn't seem to work out although I'm sure
> it would with some tweaking). However, it ends up doing exactly what I
> need it to do: get the value or return nil, in a quick-and-dirty way.

Hmm, out of interest, what didn't work out about it? Maybe I
misunderstand what you're doing, but (if you ignore the Hash-extending
silliness) it seems to work the same.

require 'test/unit'

def get_value(object, *path)
  for item in path
    break unless object
    object = object ? object[item.to_s] : nil
  end

  return object.kind_of?(String) ? object.strip : object
end

def my_get_value(hsh, *path)
  path.inject(hsh) { |obj, item| obj[item.to_s] || break }
end

class TestGetValue < Test::Unit::TestCase
  def setup
    @h = { 
      'name' => { 
        'first' => 'Ross' 
       }, 
       'contact' => { 
         'phone' => { 
           'office' => '345345' 
          } 
        } 
      }
  end

  def test_it
    assert_equal get_value(@h, :name, :first), 
                 my_get_value(@h, :name, :first)
    assert_equal get_value(@h, :name, :middle), 
                 my_get_value(@h, :name, :middle)
    assert_equal get_value(@h, :contact), 
                 my_get_value(@h, :contact)
    assert_equal get_value(@h, :contact, :phone, :office), 
                 my_get_value(@h, :contact, :phone, :office)
  end
end

# -> 1 tests, 4 assertions, 0 failures, 0 errors


The only thing I changed here is adding to_s on the item in my version,
so I could use the same hash to test both while keeping symbol keys.

-- 
Ross Bamford - rosco@roscopeco.REMOVE.co.uk