generators and migrations in plugins (rails 3)

Question

I am simply trying to create a plugin migration generator without any parameters, like : $rails generate yaffle and this should copy the migration file (lib/generators/yaffle/template/create_yaffle.rb) to db/migrate/[timestamp]_create_yaffle.rb.

1. The problem I am facing here is, its copying, but without timestamp.
2. Also, when I run $rails generate yaffle it gives me a message that arguments are not provided, it expects to be in this format rails generate yaffle NAME [options]. I dont want to have any options/arguments, it should just be rails generate yaffle.

What should I do?

I followed the generator used in acts_as_commentable , it looks pretty simple, but I don't know where to modify these settings... can anybody help?

Generator Code:

require 'rails/generators'
require 'rails/generators/migration'

class ThumbitGenerator  Rails::Generators::NamedBase
  source_root File.expand_path('../templates', __FILE__)

  def self.next_migration_number(path)
    Time.now.utc.strftime("%Y%m%d%H%M%S")
  end

  def create_model_file
    template "like.rb", "app/models/like.rb"
    template "liking.rb", "app/models/liking.rb"
    template "create_likes.rb", "db/migrate/create_likes.rb"
    template "create_likings.rb", "db/migrate/create_likings.rb"
  end

end

Answer 1

A small polish on the solution - to save yourself the hassle of defining the timestamp for the migration and future proof your generator in case Rails core team decides to use another way of stamping (e.g. SHA hashes truncated to 10 characters), you can require 'rails/generators/active_record' and extend ActiveRecord::Generators::Migration like this:

require 'rails/generators'
require 'rails/generators/migration'
require 'rails/generators/active_record'

class ThumbitGenerator < Rails::Generators::Base
  include Rails::Generators::Migration
  extend ActiveRecord::Generators::Migration

  source_root File.expand_path('../templates', __FILE__)

  def create_model_file
    template "like.rb", "app/models/like.rb"
    template "liking.rb", "app/models/liking.rb"
    migration_template "create_likes.rb", "db/migrate/create_likes.rb"
    migration_template "create_likings.rb", "db/migrate/create_likings.rb"
  end
end

UPDATE In Rails 4 ActiveRecord::Generators::Migration is no longer a module, so use instead:

require 'rails/generators'
require 'rails/generators/migration'
require 'rails/generators/active_record'

class ThumbitGenerator < Rails::Generators::Base
  include Rails::Generators::Migration
  # Implement the required interface for Rails::Generators::Migration
  def self.next_migration_number(dirname)
    ActiveRecord::Generators::Base.next_migration_number(dirname)
  end

  source_root File.expand_path('../templates', __FILE__)

  def create_model_file
    template "like.rb", "app/models/like.rb"
    template "liking.rb", "app/models/liking.rb"
    migration_template "create_likes.rb", "db/migrate/create_likes.rb"
    migration_template "create_likings.rb", "db/migrate/create_likings.rb"
  end
end