Changing ruby hash keys to symbol.

hash_key_to_sym.rb

class Hash
  def keys_to_sym
    self.each_with_object({}) do |(k, v), h|
      h[k.to_sym] = v.class == Hash ? v.keys_to_sym : v
    end
  end
end

hash = {"a" => 1, "b" => 2, "c" => {"A" => "foo", "B" => "bar"}}
hash.keys_to_sym
# => {:a=>1, :b=>2, :c=>{:A=>"foo", :B=>"bar"}}