Forum: Rails Engines development Controller Namespace Support

Hi

I'm currently working on making ActiveRBAC (https://
activerbac.turingstudio.com) into an engine.

However, there seems to be a problem with Controllers and Namespaces.
I want my controller to be in the "ActiveRBAC" namespace since
ActiveRBAC contains controllers with more or less common names such
as "UserController".

A quick look at the mail archive shows me that there are known
problems. Could someone give me an abstract of the problems? How much
work would it be to add namespace support for controllers to rails-
engines? I'd be willing to give it a try, then.

Regards

Manuel Holtgrewe

The problems stem from the strange way that Rails has been require-ing
controllers within modules. Old (1.0.0, 1.0.1) versions of the Engines
plugin would strip everything bar the filename out of the require path
in order to quickly do the code mixing, but that also removes module
information (since ActiveRBAC::UserController would be required as
'active_rbac/user_controller'). The biggest problem is that different
installations of Rails seem to use different paths when require-ing
controllers. That's what I've spent the last 3 point-releases chasing.

The current version of the Engines plugin (1.0.6) *should* fix all of
these problems - if you find you're having problems then post here
(preferrable with traces from the engine logger; see Engines.log for
details about how to turn it on) and we'll work through it.

- james

On 2/3/06, Manuel Holtgrewe <purestorm@ggnore.net> wrote:
> A quick look at the mail archive shows me that there are known
> http://lists.rails-engines.org/listinfo.cgi/engine...
>


--
* J *
  ~

Hi

> The current version of the Engines plugin (1.0.6) *should* fix all of
> these problems - if you find you're having problems then post here
> (preferrable with traces from the engine logger; see Engines.log for
> details about how to turn it on) and we'll work through it.

I did not find any documentation about how to turn on traces, the
only thing I found was a call to Engine.create_logger which I added
to my environment.rb.

The source of the engine can be found here: http://www.6URL.com/0EJE

Here is the trace:

==8<=========================
manuel@coxorange.local 17:45:58 rbac_demo $> ./script/server
=> Booting WEBrick...
Starting engine 'active_rbac' from '/Users/manuel/Development/Rails/
arbac.ts.com/rbac_demo/trunk/rbac_demo/vendor/plugins/active_rbac'
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/user to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/static_permission to
the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/shared to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/role to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/registration_mailer to
the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/registration to the
load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/login to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views/group to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/views to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/model to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/helpers to the load path
adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
rbac_demo/vendor/plugins/active_rbac/app/controllers to the load path
No init_engines.rb file found for engine 'active_rbac'...
Attempting to copy public engine files from './vendor/plugins/
active_rbac/public'
=> Rails application started on http://0.0.0.0:3000
=> Ctrl-C to shutdown server; call with --help for options
[2006-02-03 17:46:02] INFO  WEBrick 1.3.1
[2006-02-03 17:46:02] INFO  ruby 1.8.2 (2004-12-25) [powerpc-
darwin8.2.0]
[2006-02-03 17:46:02] INFO  WEBrick::HTTPServer#start: pid=6766
port=3000
Engines' require_or_load for './app/controllers/application.rb'
finally loading from application: './app/controllers/application.rb'
Engines' require_or_load for 'application_helper'
requiring helper file 'application_helper'
--> rewrote to 'application_helper'
--> checking 'active_rbac' for ./vendor/plugins/active_rbac/app/
helpers/application_helper.rb
finally loading from application: 'application_helper.rb'
Engines' require_or_load for 'application_api'
finally loading from application: 'application_api.rb'
Engines' require_or_load for 'user'
finally loading from application: 'user.rb'
Engines' require_or_load for 'group'
finally loading from application: 'group.rb'
Engines' require_or_load for 'role'
finally loading from application: 'role.rb'
Engines' require_or_load for 'static_permission'
finally loading from application: 'static_permission.rb'
Engines' require_or_load for 'user_registration'
finally loading from application: 'user_registration.rb'
Engines' require_or_load for './vendor/plugins/active_rbac/app/
controllers/user_controller.rb'
requiring controller file './vendor/plugins/active_rbac/app/
controllers/user_controller.rb'
--> rewrote to 'user_controller.rb'
--> checking 'active_rbac' for ./vendor/plugins/active_rbac/app/
controllers/user_controller.rb
--> found, loading from engine 'active_rbac'
Engines' require_or_load for 'vendor/plugins/active_rbac/app/helpers/
rbac_helper'
requiring helper file 'vendor/plugins/active_rbac/app/helpers/
rbac_helper'
--> rewrote to 'rbac_helper'
--> checking 'active_rbac' for ./vendor/plugins/active_rbac/app/
helpers/rbac_helper.rb
--> found, loading from engine 'active_rbac'
finally loading from application: 'vendor/plugins/active_rbac/app/
helpers/rbac_helper.rb'
Engines' require_or_load for 'active_rbac'
finally loading from application: 'active_rbac.rb'
127.0.0.1 - - [03/Feb/2006:17:46:15 CET] "GET /user HTTP/1.1" 500 10329
- -> /user
==8<=========================

Regards

Manuel Holtgrewe

You need to remembered to put your modularized controllers into
subfolders, i.e. "class ActiveRbac::UserController < .... " would go
into 
./vendor/plugins/active_rbac/app/controllers/active_rbac/user_controller.rb....

- james

On 2/3/06, Manuel Holtgrewe <purestorm@ggnore.net> wrote:
>
> rbac_demo/vendor/plugins/active_rbac/app/views/user to the load path
> adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
> adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
> darwin8.2.0]
> Engines' require_or_load for 'application_api'
> finally loading from application: 'user_registration.rb'
> requiring helper file 'vendor/plugins/active_rbac/app/helpers/
> - -> /user
> http://lists.rails-engines.org/listinfo.cgi/engine...
>


--
* J *
  ~

"need to remember" - d'oh. Bad typing today.

On 2/3/06, James Adam <james.adam@gmail.com> wrote:
> > > these problems - if you find you're having problems then post here
> >
> > adding /Users/manuel/Development/Rails/arbac.ts.com/rbac_demo/trunk/
> > rbac_demo/vendor/plugins/active_rbac/app/views/login to the load path
> > No init_engines.rb file found for engine 'active_rbac'...
> > finally loading from application: './app/controllers/application.rb'
> > Engines' require_or_load for 'group'
> > controllers/user_controller.rb'
> > helpers/rbac_helper.rb
> >
> --
> * J *
>   ~
>


--
* J *
  ~

Am 03.02.2006 um 17:55 schrieb James Adam:

> You need to remembered to put your modularized controllers into
> subfolders, i.e. "class ActiveRbac::UserController < .... " would go
> into ./vendor/plugins/active_rbac/app/controllers/active_rbac/ 
> user_controller.rb....

OK.

IMO this is not exactly elegant. Shouldn't all classes be prefixed by
the engine's name automatically?

Regards

Manuel Holtgrewe

Do you mean that every class in the engine 'MyEngine' should be put
into the module MyEngine?

i.e. class User < ActiveRecord::Base automatically becomes class
MyEngine::User < ActiveRecord::Base ?

While something like this is superficially appealing, it's actually
way more complicated to implement (even Rails doesn't support this
yet) and IMHO adding 'more magic' at this point isn't a brilliant
idea.

When you're writing a regular Rails application, any controllers that
are within modules have to reside in a sub-folder of the
app/controllers directory - there's no way around that. This is
mirrored directly in the way that Engines work - if you want your
controllers to be in modules, you have to put them in subfolders; the
fact they're in an engine isn't important.

The way that Rails controllers exist within Modules is pretty much a
hack in Rails itself right now. The module is half there for reloading
purposes, and half for routing (i.e. to let you put controllers under
subdirectories on your site).

So to answer your point - it's no more or no less elegant than if you
were developing the controllers in your application directly. Only
time will tell how things might be improved.

- james

On 2/3/06, Manuel Holtgrewe <purestorm@ggnore.net> wrote:
> IMO this is not exactly elegant. Shouldn't all classes be prefixed by
> http://lists.rails-engines.org/listinfo.cgi/engine...
>


--
* J *
  ~

Am 03.02.2006 um 18:55 schrieb James Adam:

> Do you mean that every class in the engine 'MyEngine' should be put
> into the module MyEngine?
>
> i.e. class User < ActiveRecord::Base automatically becomes class
> MyEngine::User < ActiveRecord::Base ?
>
> While something like this is superficially appealing, it's actually
> way more complicated to implement (even Rails doesn't support this
> yet) and IMHO adding 'more magic' at this point isn't a brilliant
> idea.

Actually, it would be enough if I could write this in my active_rbac
engine:

   class ActiveRbac::UserController
     # ...
   end

This means that the load-routing would have to be changed...

> subdirectories on your site).
Do you by chance know where to look for that magic in Rails? I want
to have a look and could drop half an our searching if you know it
off your head.

Regards

Manuel Holtgrewe

James,

Would you be interested in such a change as I described in my
previous email (quoted below).

Regards,

Manuel

Am 04.02.2006 um 12:43 schrieb Manuel Holtgrewe:

> Actually, it would be enough if I could write this in my active_rbac
> engine:
>
>    class ActiveRbac::UserController
>      # ...
>    end
>
> This means that the load-routing would have to be changed...

snip

On 2/19/06, Manuel Holtgrewe <purestorm@ggnore.net> wrote:
> > Actually, it would be enough if I could write this in my active_rbac
> > engine:
> >
> >    class ActiveRbac::UserController
> >      # ...
> >    end
> >
> > This means that the load-routing would have to be changed...

At the moment, writing this code means that you would get the URL
'/active_rbac/user' - this is 'standard' for all controllers in
modules, but the controller MUST exist in a subddirectory. From what I
can gather, it sounds like you're looking to avoid the requirement
that such a controller is in an 'active_rbac' subdirectory.

I suspect that doing this would require the engines plugin to provide
a fairly complete alternative routing system, and
auto-dependency-loading mechanism too, since this type of behaviour
isn't supported by what Rails provides *at all*. For me, the price of
having to create a few subfolders is by far outweighed by the hassle
of having to develop and then support a whole new dependency layer.

> > Do you by chance know where to look for that magic in Rails? I want
> > to have a look and could drop half an our searching if you know it
> > off your head.

To understand what Rails is doing when it loads controllers, you need
to start by looking at the following files:

  activesupport/lib/active_support/dependencies.rb
  actionpack/lib/action_controller/routing.rb (at the auto-generated
recognize! method)

Personally, I'd like to see the amount of magic that the engines
plugin has to perform actually reduce, rather than increase, since it
makes it much more likely that we can reuse core behaviour. It also
means that developers aren't surprised by the behaviour they see, and
can use their experience with 'normal' rails applications to greatest
effect when developing engines. Principle of Least Surprise,
basically.

Aesthetically, i completely sympathise with what you're suggesting,
and if the Rails dependency loading system could support something
like that easily then it wouldn't be an issue at all... but at the
moment, there doesn't seem to be a simple way of doing this.

--
* J *
  ~