1 files changed, 50 insertions, 0 deletions
diff --git a/railties/lib/generators/active_record.rb b/railties/lib/generators/active_record.rb
index be5d033868..2c4c3286d4 100644
--- a/railties/lib/generators/active_record.rb
+++ b/railties/lib/generators/active_record.rb
@@ -1,8 +1,58 @@
 require 'generators/named_base'
+require 'active_record'
 
 module ActiveRecord
   module Generators
+    module Migration
+
+      # Creates a migration template at the given destination. The difference
+      # to the default template method is that the migration number is appended
+      # to the destination file name.
+      #
+      # The migration number, migration file name, migration class name are
+      # available as instance variables in the template to be rendered.
+      #
+      # ==== Examples
+      #
+      #   migration_template "migrate.rb", "db/migrate/add_foo_to_bar"
+      #
+      def migration_template(source, destination=nil, log_status=true)
+        destination = File.expand_path(destination || source, self.destination_root)
+
+        migration_dir = File.dirname(destination)
+        @migration_number     = next_migration_number(migration_dir)
+        @migration_file_name  = File.basename(destination).sub(/\.rb$/, '')
+        @migration_class_name = @migration_file_name.camelize
+
+        if existing = migration_exists?(migration_dir, @migration_file_name)
+          raise Rails::Generators::Error, "Another migration is already named #{@migration_file_name}: #{existing}"
+        end
+
+        destination = File.join(migration_dir, "#{@migration_number}_#{@migration_file_name}.rb")
+        template(source, destination, log_status)
+      end
+
+      protected
+
+        def migration_exists?(dirname, file_name) #:nodoc:
+          Dir.glob("#{dirname}/[0-9]*_*.rb").grep(/\d+_#{file_name}.rb$/).first
+        end
+
+        def current_migration_number(dirname) #:nodoc:
+          Dir.glob("#{dirname}/[0-9]*_*.rb").collect{ |f| f.split("_").first.to_i }.max
+        end
+
+        def next_migration_number(dirname) #:nodoc:
+          if ActiveRecord::Base.timestamped_migrations
+            Time.now.utc.strftime("%Y%m%d%H%M%S")
+          else
+            "%.3d" % (current_migration_number(dirname) + 1)
+          end
+        end
+    end
+
     class Base < Rails::Generators::NamedBase
+      include Migration
     end
   end
 end