Ss::PersistentJhash

gistfile1.rb

#
# Public: This class uses Rubys native hash data type for immediate data manipulation.  This serializes the data to JSON where it is stored into a Redis backend for persistence.
# It contains a namespace and a rd_key, it will store the data as JSON into "[namespace]:[key]"
# 
#  Assumes REDIS = Redis.new (redis connection) 
#
# Examples
#
#   foo = PersistentJhash.new
#   foo.namespace
#   # => "persistent_jhash"
#   foo.rd_key
#   # => "persistent_jhash"
#
#   bar = PersistentJhash.new(ns: "ss:bar")
#   bar.namespace
#   # => "ss:bar"
#   bar.rd_key
#   # => "bar"
#
#   baz = PersistentJhash.new(rk: "another_key")
#   baz.namespace
#   # => "persistent_jhash"
#   baz.rd_key
#   # => "another_key"
#
#   foo = PersistentJhash.new(rk: :test)
#   # => {}
#   foo + { name: "Joe", favorite_numbers: [ 1, 2, 3 ] }
#   # => { name: "Joe", favorite_numbers: [ 1, 2, 3 ] }
#   foo.save
#   # => saved to "persistent_jhash:test"
#
#   foo = PersistentJhash.new(rk: :test)
#   # => {}
#   foo.load_data
#   # => { name: "Joe", favorite_numbers: [ 1, 2, 3 ] }
module Ss
  class PersistentJhash < Hash

    def initialize(params = {})
      ns, rk = params[:ns], params[:rk]
      self.namespace  = ns.to_s if ns
      self.rd_key     = rk.to_s if rk
    end

    alias_method :+, :merge

    def load_data
      replace JSON.parse(conn[rd_key])
    end

    def save
      conn[rd_key] = to_json
      self
    end

    def namespace
      @namespace ||= ns(self.class.to_s)
    end

    def rd_key
      @rd_key ||= namespace.split(/:/).last
    end

    def reset
      @conn = nil
    end

    private
    attr_writer :namespace, :rd_key

    #  snakecase, double-colons to single-colons
    #  ns("Ss::PersistentJhash")
    #  # => "ss:persistent_jhash"
    def ns(str)
      str.gsub(/::/, ':').
      gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
      gsub(/([a-z\d])([A-Z])/,'\1_\2').
      tr("-", "_").
      downcase
    end

    def raw
      conn[rd_key]
    end

    def conn
      @conn ||= Redis::Namespace.new(namespace, :redis => REDIS)
    end
  end
end