Best way to convert strings to symbols in hash

Question

What\'s the (fastest/cleanest/straightforward) way to convert all keys in a hash from strings to symbols in Ruby?

This would be handy when parsing YAML.

Answer 1

Similar to previous solutions but written a bit differently.

• This allows for a hash that is nested and/or has arrays.
• Get conversion of keys to a string as a bonus.

• Code does not mutate the hash been passed in.

  module HashUtils
    def symbolize_keys(hash)
      transformer_function = ->(key) { key.to_sym }
      transform_keys(hash, transformer_function)
    end
  
    def stringify_keys(hash)
      transformer_function = ->(key) { key.to_s }
      transform_keys(hash, transformer_function)
    end
  
    def transform_keys(obj, transformer_function)
      case obj
      when Array
        obj.map{|value| transform_keys(value, transformer_function)}
      when Hash
        obj.each_with_object({}) do |(key, value), hash|
          hash[transformer_function.call(key)] = transform_keys(value, transformer_function)
        end
      else
        obj
      end
    end
  end