Rails 3.1 Engines: Full vs. Mountable

Hi all,

I was hoping someone could please clarify the differences between a
full engine and a mountable one.

I have noticed the following:

** Full Engine **

  • With a full engine, the parent application inherits the routes from
    the engine. It is not necessary to specify anything in parent_app/
    config/routes.rb. Specifying the gem in Gemfile is enough. The
    engine routes are specified as:

my_engine/config/routes.rb

Rails.application.routes.draw do

whatever

end

  • No namespacing of models, controllers, etc. These are immediately
    accessible to the parent application.

** Mountable Engine **

  • The engine’s namespace is isolated by default.

my_engine/lib/my_engine/engine.rb

module MyEngine
class Engine < Rails::Engine
isolate_namespace MyEngine
end
end

  • With a mountable engine, the routes are namespaced and the parent
    app can bundle this functionality under a single route:

my_engine/config/routes.rb

MyEngine::Engine.routes.draw do
#whatever
end

parent_app/config/routes.rb

Rails.application.routes.draw do
mount MyEngine::Engine => “/engine”, :as => “namespaced”
end

  • Models, controllers, etc are isolated from the parent application -
    although helpers can be shared easily.

Is this correct and are these the main differences? Are there any
other differences between a full and mountable engine that I missed?

Thanks,
Adam

I take it no one has poked around with the Rails 3.1 engines yet?

-Adam

I’m interested in this, too, but I haven’t used 3.1 yet. Let us know
what you find out!

Hi Paul,

Here’s what I have found so far:

http://www.astjohn.ca/blog/rails-31-engines-mountable-or-full-part-1

I’ll post Part 2 later tonight. Hope that helps you out.

Cheers,
Adam