Contents

module SimpleStateMachine
  
  def self.included(base)
    base.extend Macro
  end
  
  module Macro
    def state_machine(column, states)
      create_empty_state_machine unless inheritable_attributes.key? :states
      inheritable_attributes[:states][column.to_sym] = states
      validates_inclusion_of column, :in => states
      # should also override getter/setter to convert to strings
      self.class_eval <<-eos
        def #{column.to_s}=(value)
          self[:#{column.to_s}] = value.to_s
        end
        def #{column.to_s}
          self[:#{column.to_s}].to_sym
        end
        def #{column.to_s}_revert
          self[:#{column.to_s}] = self.new_record? ? states[:#{column.to_s}].first.to_s : self.#{column.to_s}_was
        end
      eos

      # define a method {state_column}_{state}? for each state
      states.each do |state|
        self.class_eval <<-eos
          def #{column.to_s}_#{state.to_s}?
            self[:#{column.to_s}] === "#{state.to_s}"
          end
        eos
      end

    end

  private

    def create_empty_state_machine
      write_inheritable_attribute :states, {} # add a class variable
      class_inheritable_reader    :states     # make it read-only
      
      # set initial states on new objects
      if(!instance_methods.include?("after_initialize") && ActiveRecord::VERSION::MAJOR < 3)
        self.class_eval do
          def after_initialize # ActiveRecord::Base requires explicit definition of this function to use the callback
          end
        end
      end
      after_initialize :set_initial_states
      self.class_eval do
        def set_initial_states
          states.each {|column, states|
            self[column] = states.first.to_s
          } if new_record?
        end
      end
    end
  end
end

ActiveRecord::Base.class_eval do
  include SimpleStateMachine
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
openhood-simple_state_machine-1.0.1	lib/simple_state_machine.rb