This gem allows you to access nested Ruby collections (Hash, Array, etc) using keypaths.

For example, say you had a nested data structure like:

data = {
    :item_one => {:id => 1, :url => 'http://nickcharlton.net/'},
    :something_else => [
        {
            :id => 1,
            :url => 'https://github.com/'
        }
    ]
}

You could access "https://github.com/" through: something_else.0.url. Basically, this is intended to allow you to manipulate/transform large nested structures that you might get back from a JSON document.

keypath-ruby is on RubyGems as key_path. But you can also add the repo to your Gemfile:

gem 'key_path', :git => 'https://github.com/nickcharlton/keypath-ruby.git'

KeyPath is at least two things. First, it's a class (actually, KeyPath::Path) which represents a path (this is just a string, and has methods to go back and forth from it) and secondly a set of class extensions for Enumerable, Hash and String which allow you to use the native collection classes with keypaths.

require 'key_path'

data = {
    :item => {
        :url => 'http://nickcharlton.net'
    }
}

# fetching a path
path = KeyPath::Path.new 'item.url'
data.value_at_keypath(path) #=> 'http://nickcharlton.net'

# finding all `:url` paths in a collection
data.keypaths_for_nested_key(:url) #=> {item.url => 'http://nickcharlton.net'}

# going back and forth from a string
path.to_s #=> 'item.url'
'item.url'.to_keypath #=> #<KeyPath:70096895112220 path=item.url>

# get the parent of a keypath (or nil, if there isn't one)
path.parent #=> #<KeyPath:70096895221110 path=item>

# setting a path
data.set_keypath(path, 'http://github.com/')

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

Copyright (c) 2013 Nick Charlton (nick@nickcharlton.net)