Forum: Rails Engines Calling methods from the "main" application

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Chris C. (Guest)
on 2006-03-22 17:56
I've successfully setup a publication engine (Publish) which I use to
learn ROR but there is something I can't find a solution for : the main
application (the one which make uses of this engine) has a "admin"
layout which need to get a menu for EVERY engine installed... Let's call
it getMenu()

1) I don't know where to define getMenu() - I've tried in several places
- init_engine.rb included but got several error messages (ranging from
"method not found" to "trying to access private method")
2) How can I iterate throught all the engines installed and check if the
getMenu method exists ?

Point 1 is the most important for me as I don't understand how I can
make methods and attributes accessible to the outside world. For now,
every piece of code executed by my engine is the result of a
controller/action sequence.

Same goes for engine to engine calls... How can I do ?

Thanks
James A. (Guest)
on 2006-03-22 18:08
(Received via mailing list)
Hi,

Firstly, to get an array of all the running engines, you can use
simply Engines.active - that part is easy. Read the Engines RDoc for
more details.

You should define your getMenu() method as part of some module, and
use a consistent convention for the naming of those modules. For
instance, if you have three engines ('alpha_engine', 'beta_engine',
'gamma_engine'), then you will probably be defining modules for each
of those engines, so you could have:

/vendor/plugins/alpha_engine/lib/alpha_engine.rb:
  module AlphaEngine
    def AlphaEngine.getMenu()
       #...
    end
  end

... and so on for BetaEngine and GammaEngine.

That said, where you place the method really depends what your getMenu
method does. You might instead want to put it in an appropriately
named module within the app/helpers directory of each engine. The key
to detecting the availablity of this method is going to be following a
well-defined convention for it's placement.

- james

On 3/22/06, Christophe C. <removed_email_address@domain.invalid> wrote:
> getMenu method exists ?
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> engine-users mailing list
> removed_email_address@domain.invalid
> http://lists.rails-engines.org/listinfo.cgi/engine...
>


--
* J *
  ~
Chris C. (Guest)
on 2006-03-22 19:35
Thank you for your help James, using your solution I solved my problem
in a minute...

Now, you said that I could use the same solution and put getMenu() in a
helper.. It would be better because the script in the lib directory is
only reloaded when webrick starts - So, I've tried with something in a
helper (helper directory under my engine):

module PublishHelper

  def PublishHelper.getmenu()
    # snip
  end

end

But that doesn't work - In the app's layout , using
PublishHelper::getmenu produces an error "uninitialized constant
ArticleHelper"

Is there something special to do to use helpers or each script in the
engine's helper directory is automatically provided to the main
application ?
James A. (Guest)
on 2006-03-22 19:40
(Received via mailing list)
Helpers are automatically loaded by controllers if they share the same
root name, i.e. the 'PublishController' will try and load the
'PublishHelper'... if you want to include other helpers, you need to
explicitly include them in your controller, probably using the
'helper' class method, i.e.

  class PublishHelper < ApplicationController
    helper :article
    # ..
  end

BTW, to call a 'class-level' method, you should be using
PublishHelper.getmenu(), rather than PublishHelper::getmenu()

- james

On 3/22/06, Christophe C. <removed_email_address@domain.invalid> wrote:
>   def PublishHelper.getmenu()
> engine's helper directory is automatically provided to the main
> application ?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> engine-users mailing list
> removed_email_address@domain.invalid
> http://lists.rails-engines.org/listinfo.cgi/engine...
>


--
* J *
  ~
Chris C. (Guest)
on 2006-03-23 12:11
Thanks again James - This timeit works also with an helper ! But I
wonder why the helpers are not reloaded dynamically ?
I'm working in development mode and I need to restart WebRicks to see
the results of the changes made in the helper source code...
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