path: root/railties/doc/guides/source/creating_plugins/custom_generator.txt

== Add a custom generator command ==

You may have noticed above that you can used one of the built-in rails migration commands `m.migration_template`.  You can create your own commands for these, using the following steps:

 1. Add the require and hook statements to init.rb.
 2. Create the commands - creating 3 sets, Create, Destroy, List.
 3. Add the method to your generator.

Working with the internals of generators is beyond the scope of this tutorial, but here is a basic example:

*vendor/plugins/yaffle/init.rb*

[source, ruby]
-----------------------------------------------------------
require "commands"
Rails::Generator::Commands::Create.send   :include,  Yaffle::Generator::Commands::Create
Rails::Generator::Commands::Destroy.send  :include,  Yaffle::Generator::Commands::Destroy
Rails::Generator::Commands::List.send     :include,  Yaffle::Generator::Commands::List
-----------------------------------------------------------

*vendor/plugins/yaffle/lib/commands.rb*

[source, ruby]
-----------------------------------------------------------
require 'rails_generator'
require 'rails_generator/commands'

module Yaffle #:nodoc:
  module Generator #:nodoc:
    module Commands #:nodoc:
      module Create
        def yaffle_definition
          file("definition.txt", "definition.txt")
        end
      end

      module Destroy
        def yaffle_definition
          file("definition.txt", "definition.txt")
        end
      end

      module List
        def yaffle_definition
          file("definition.txt", "definition.txt")
        end
      end
    end
  end
end
-----------------------------------------------------------

*vendor/plugins/yaffle/generators/yaffle/templates/definition.txt*
-----------------------------------------------------------
Yaffle is a bird
-----------------------------------------------------------

*vendor/plugins/yaffle/generators/yaffle/yaffle_generator.rb*

[source, ruby]
-----------------------------------------------------------
class YaffleGenerator < Rails::Generator::NamedBase
  def manifest
    m.yaffle_definition
  end
end
-----------------------------------------------------------

This example just uses the built-in "file" method, but you could do anything that Ruby allows.