1 files changed, 10 insertions, 5 deletions
diff --git a/railties/lib/rails/generators/migration.rb b/railties/lib/rails/generators/migration.rb
index 51e6d68bf0..a755471a4b 100644
--- a/railties/lib/rails/generators/migration.rb
+++ b/railties/lib/rails/generators/migration.rb
@@ -10,26 +10,31 @@ module Rails
       extend ActiveSupport::Concern
       attr_reader :migration_number, :migration_file_name, :migration_class_name
 
-      module ClassMethods
-        def migration_lookup_at(dirname) #:nodoc:
+      module ClassMethods #:nodoc:
+        def migration_lookup_at(dirname)
           Dir.glob("#{dirname}/[0-9]*_*.rb")
         end
 
-        def migration_exists?(dirname, file_name) #:nodoc:
+        def migration_exists?(dirname, file_name)
           migration_lookup_at(dirname).grep(/\d+_#{file_name}.rb$/).first
         end
 
-        def current_migration_number(dirname) #:nodoc:
+        def current_migration_number(dirname)
           migration_lookup_at(dirname).collect do |file|
             File.basename(file).split("_").first.to_i
           end.max.to_i
         end
 
-        def next_migration_number(dirname) #:nodoc:
+        def next_migration_number(dirname)
           raise NotImplementedError
         end
       end
 
+      def id_kind
+        kind = Rails.application.config.active_record.primary_key rescue nil
+        ", id: :#{kind}" if kind
+      end
+
       def create_migration(destination, data, config = {}, &block)
         action Rails::Generators::Actions::CreateMigration.new(self, destination, block || data.to_s, config)
       end