A basic DataMapper Type to represent unique API keys.

dm_api_key.rb

require 'digest/sha2'

module DataMapper
  module Types
    class APIKey < DataMapper::Type

      primitive String
      length 64

      #
      # Loads the API key from the database.
      #
      # @param [String, nil] value
      #   The value loaded from the database.
      #
      # @return [String]
      #   The unique API key.
      #
      def self.load(value, property)
        if value.blank?
          generate_api_key
        else
          value
        end
      end

      #
      # Dumps the API key out into a storable format.
      #
      # @param [String, nil] value
      #   The value to dump.
      #
      # @return [String]
      #   A storable API key.
      #
      def self.dump(value, property)
        if value.blank?
          nil
        else
          value.to_s
        end
      end

      #
      # Typecasts a value into an API key.
      #
      # @param [Object, String, nil] value
      #   The value to typecast.
      #
      # @return [String]
      #   The API key which represents the given value. If `nil` was given
      #   as the value, a new API key will be generated.
      #
      def self.typecast(value, property)
        if value.kind_of?(Digest::Base)
          value.hexdigest
        elsif value.nil?
          generate_api_key
        else
          Digest::SHA256.hexdigest(value.to_s)
        end
      end

      #
      # Generates a new unique API key, by calculating the SHA256 digest
      # of the current time and random characters.
      #
      # @return [String]
      #   A unique API key.
      #
      def self.generate_api_key
        unique = Time.now.to_i
        salt = lambda { Array.new(10) { rand(256) }.join }

        digest = Digest::SHA256.new()

        digest << salt.call()
        digest << unique.to_s
        digest << salt.call()

        return digest.hexdigest
      end

    end
  end
end