Loading .yml configuration data with the code from http://speakmy.name/2011/05/29/simple-configuration-for-ruby-apps

app_data.rb

module AppData

#require 'deep_symbolizable'

  # again - it's a singleton, thus implemented as a self-extended module
  extend self

  @_settings = {}
  attr_reader :_settings

  # This is the main point of entry - we call Settings.load! and provide
  # a name of the file to read as it's argument. We can also pass in some
  # options, but at the moment it's being used to allow per-environment
  # overrides in Rails
  def load!(filename, options = {})
    newsets = YAML::load_file(filename).deep_symbolize
    newsets = newsets[options[:env].to_sym] if \
                                               options[:env] && \
                                               newsets[options[:env].to_sym]
    deep_merge!(@_settings, newsets)
  end

  # Deep merging of hashes
  # deep_merge by Stefan Rusterholz, see http://www.ruby-forum.com/topic/142809
  def deep_merge!(target, data)
    merger = proc{|key, v1, v2|
      Hash === v1 && Hash === v2 ? v1.merge(v2, &merger) : v2 }
    target.merge! data, &merger
  end

  def method_missing(name, *args, &block)
    @_settings[name.to_sym] ||
    fail(NoMethodError, "unknown configuration root #{name}", caller)
  end

end

deep_symbolizable.rb

# Symbolizes all of hash's keys and subkeys.
# Also allows for custom pre-processing of keys (e.g. downcasing, etc)
# if the block is given:
#
# somehash.deep_symbolize { |key| key.downcase }
#
# Usage: either include it into global Hash class to make it available to
# to all hashes, or extend only your own hash objects with this
# module.
# E.g.:
# 1) class Hash; include DeepSymbolizable; end
# 2) myhash.extend DeepSymbolizable

module DeepSymbolizable

  class Hash
    include DeepSymbolizable
  end
  
  def deep_symbolize(&block)
    method = self.class.to_s.downcase.to_sym
    syms = DeepSymbolizable::Symbolizers
    syms.respond_to?(method) ? syms.send(method, self, &block) : self
  end

  module Symbolizers
    extend self

    # the primary method - symbolizes keys of the given hash,
    # preprocessing them with a block if one was given, and recursively
    # going into all nested enumerables
    def hash(hash, &block)
      hash.inject({}) do |result, (key, value)|
        # Recursively deep-symbolize subhashes
        value = _recurse_(value, &block)

        # Pre-process the key with a block if it was given
        key = yield key if block_given?
        # Symbolize the key string if it responds to to_sym
        sym_key = key.to_sym rescue key

        # write it back into the result and return the updated hash
        result[sym_key] = value
        result
      end
    end

    # walking over arrays and symbolizing all nested elements
    def array(ary, &block)
      ary.map { |v| _recurse_(v, &block) }
    end

    # handling recursion - any Enumerable elements (except String)
    # is being extended with the module, and then symbolized
    def _recurse_(value, &block)
      if value.is_a?(Enumerable) && !value.is_a?(String)
        # support for a use case without extended core Hash
        value.extend DeepSymbolizable unless value.class.include?(DeepSymbolizable)
        value = value.deep_symbolize(&block)
      end
      value
    end
  end

end

class Hash; include DeepSymbolizable; end

rails console output

marks-imac:lib railsdev$ pwd
/Users/railsdev/Development/railsprojects/Learning/Marks-Attempts/Test-Area/bootstrap-dropdown-buttons/lib
marks-imac:lib railsdev$ cd generic_search/
marks-imac:generic_search railsdev$ rails c
Loading development environment (Rails 3.2.5)
1.9.3-p125 :001 > AppData.load!("#{Rails.root}/config/initializers/search_configurations.yml")
NameError: uninitialized constant AppData
	from (irb):1
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands/console.rb:47:in `start'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands/console.rb:8:in `start'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands.rb:41:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'
1.9.3-p125 :002 > GenericSearch::AppData.load!("#{Rails.root}/config/initializers/search_configurations.yml")
LoadError: Expected /Users/railsdev/Development/railsprojects/Learning/Marks-Attempts/Test-Area/bootstrap-dropdown-buttons/lib/generic_search/app_data.rb to define GenericSearch::AppData
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:503:in `load_missing_constant'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:192:in `block in const_missing'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:190:in `each'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/activesupport-3.2.5/lib/active_support/dependencies.rb:190:in `const_missing'
	from (irb):2
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands/console.rb:47:in `start'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands/console.rb:8:in `start'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands.rb:41:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'
1.9.3-p125 :003 > GenericSearch
 => GenericSearch 
1.9.3-p125 :004 > AppData.load!("#{Rails.root}/config/initializers/search_configurations.yml")
NoMethodError: undefined method `deep_symbolize' for #<Hash:0x007fe146e2abd8>
	from /Users/railsdev/Development/railsprojects/Learning/Marks-Attempts/Test-Area/bootstrap-dropdown-buttons/lib/generic_search/app_data.rb:16:in `load!'
	from (irb):4
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands/console.rb:47:in `start'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands/console.rb:8:in `start'
	from /Users/railsdev/.rvm/gems/ruby-1.9.3-p125@bootstrap-dropdown-buttons/gems/railties-3.2.5/lib/rails/commands.rb:41:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'
1.9.3-p125 :005 > 

search_configurations.yml

# Search Conditions
#   manually configured
#
#   EDIT with CARE
#   
generic_conditions:
 - contains
 - equals
 - 'starts with'
 - 'ends with'
 - 'from/to'
 - 'matches'

models:
  diagnosis:
    fields: 
     - code
     - description
    conditions: 
      - contains
      - equals
      - 'starts with'
      - 'ends with'
      - 'from/to'
      - 'matches'
  services:
    fields: 
      code:
       - contains
       - equals
       - 'starts with'
       - 'ends with'
       - matches
      description:
       - 'valid from'

emails:
  admin:    someadmin@somewhere.net
  support:  support@somewhere.net

urls:
  search:   http://google.com
  blog:     http://speakmy.name

Thanks

I can see I need to remove the class Hash I had in DeepSymbolizable (which I had put up near the top).

Another simple question. I thought in rails console (rails c) reload! reloaded the environment? I think part of my problem was that I assumed this would pick up changes I had made to the files (after saving), but when I had made all the changes they still didn't work with a simple reload!

I was getting the error:
1.9.3-p125 :026 > reload!
Reloading...
=> true
1.9.3-p125 :027 > AppData.load!("#{Rails.root}/config/initializers/search_configurations.yml")
NameError: uninitialized constant AppData

Have I misunderstood what reload! in Rails console does?

Also, if I want to store this code except the .yml file in lib what do I need to do? I assume its just setup the autoload which I already had?

Really appreciate your help on this

reload! does reload the application code indeed, but it does not always pickup changes made to you basic environment settings (such at the ones you do in config/application.rb or config/environments/*), and also I had it not reloading changes in initializers as well. Restarting the console helps in this cases, and sometimes it affects the server running dev environment, too - again, restarting the server helps.

Regarding placing your code in lib - of course, you can do it. You can put the code for the module itself in, say, lib/deep_symbolizable.rb, make sure it is required or auto-loaded, and include the method into Hash class in an initializer - basically just take the last line from deep_symbolizable.rb above and put it into config/initializers/app_data.rb, followed by loading of yml files.