what is the best way to convert a json formated key value pair to ruby hash with symbol as key?

I am wondering what is the best way to convert a json formated key value pair to ruby hash with symbol as key : examole:

{ 'user': { 'name': 'foo', 'age': 40, 'location': { 'city' : 'bar', 'state': 'ca' } } }
==> 
{ :user=>{ :name => 'foo', :age =>'40', :location=>{ :city => 'bar', :state=>'ca' } } }

Is there a helper method can do this?

From stackoverflow

• Of course, there is a json gem, but that handles only double quotes.

  edavey : As madlep says below - that's all you need if you know that the JSON will be valid (e.g. you're making it yourself!)

  Justin L. : This doesn't work. `JSON.parse(JSON.generate([:a])) # => ["a"]`

  Leventix : That's because JSON can't represent symbols. You can use: `Marshal.load(Marshal.dump([:a]))` instead.

• There isn't anything built in to do the trick, but it's not too hard to write the code to do it using the JSON gem. There is a symbolize_keys method built into Rails if you're using that, but that doesn't symbolize keys recursively like you need.

  require 'json'
  
  def json_to_sym_hash(json)
    json.gsub!('\'', '"')
    parsed = JSON.parse(json)
    symbolize_keys(parsed)
  end
  
  def symbolize_keys(hash)
    hash.inject({}){|new_hash, key_value|
      key, value = key_value
      value = symbolize_keys(value) if value.is_a?(Hash)
      new_hash[key.to_sym] = value
      new_hash
    }
  end
  

  As Leventix said, the JSON gem only handles double quoted strings (which is technically correct - JSON should be formatted with double quotes). This bit of code will clean that up before trying to parse it.