add support for secondary sequences

lib/sequenced/acts_as_sequenced.rb

@@ -29,6 +29,10 @@ module ClassMethods
       #           :skip     - Skips the sequential ID generation when the lambda
       #                       expression evaluates to nil. Gets passed the
       #                       model object
+      #           :secondary
+      #             :column - Column for secondary index
+      #             :value  - lambda expression that you want to use to generate value for secondary index.
+      #                       Accepts two attributes: record and next_id
       #
       # Examples
       #

lib/sequenced/generator.rb

@@ -1,19 +1,22 @@
 module Sequenced
   class Generator
-    attr_reader :record, :scope, :column, :start_at, :skip
+    attr_reader :record, :scope, :column, :start_at, :skip, :secondary_column, :secondary_value_generator
 
     def initialize(record, options = {})
       @record = record
       @scope = options[:scope]
       @column = options[:column].to_sym
       @start_at = options[:start_at]
       @skip = options[:skip]
+      @secondary_column = options.dig(:secondary, :column)
+      @secondary_value_generator = options.dig(:secondary, :value)
     end
 
     def set
       return if skip? || id_set?
       lock_table
       record.send(:"#{column}=", next_id)
+      set_secondary_sequence(next_id)
     end
 
     def id_set?
@@ -79,5 +82,10 @@ def max(*values)
       values.to_a.max
     end
 
+    def set_secondary_sequence(next_id)
+      return if secondary_column.blank? || secondary_value_generator.blank?
+
+      record.send(:"#{secondary_column}=", secondary_value_generator.call(record, next_id))
+    end
   end
 end