Ever had a hash which contained strings as keys and needed symbols instead? I do: From a REXML::Document I created a hash. Unfortunately, the keys were all strings and I needed them to be symbols at some other point in the app. Thank god, Ruby is capable of extending any object “on the fly”. So, I wrote a simple extension to Hash, which you might find useful as well:

class Hash
  #take keys of hash and transform those to a symbols
  def self.transform_keys_to_symbols(value)
    return value if not value.is_a?(Hash)
    hash = value.inject({}){|memo,(k,v)| memo[k.to_sym] = Hash.transform_keys_to_symbols(v); memo}
    return hash
  end
end

Usage is:

a = { "key" => 123, "inner_hash" => { "another_key" => "blabla" }}
Hash.transform_keys_to_symbols(a)
#returns
a = { :key => 123, :inner_hash => { :another_key => "blabla" }}

This entry was posted on Wednesday, August 19th, 2009 at 15:55 and is filed under Programming the web, ruby on rails. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.