Puppet func, lookups array of hashes by key and value

hash_detect

# Put in $module/lib/puppet/parser/functions/hash_detect.rb

module Puppet::Parser::Functions
  newfunction(:hash_detect, :type => :rvalue, :doc => <<-EOS
      Take array of hashes and key and value for search and optional key whom value should be returned.
    EOS
  ) do |arguments|

    haystack  = arguments[0]
    key       = arguments[1]
    value     = arguments[2]
    final_key = arguments[3]

    needle = haystack.detect do |hash|
      raise Puppet::ParseError, "Provided hash doesn't have key=#{key}" unless hash.has_key?(key)
      hash[key] == value
    end

    raise Puppet::ParseError, "Provided hash doesn't have tupple (#{key},#{value})" unless needle

    if final_key 
      raise Puppet::ParseError, "Provided hash doesn't have key=#{final_key}" unless needle.has_key?(final_key)
      needle[final_key]
    else
      needle 
    end
  end
end