Rails - Feb 2006 - how would you implement this normalizer?

Names of models in my application have accented characters that imply  
unexpected orderings. For instance ?vila should go before Madrid, but  
String#<=> puts it the other way aroud.

I am only sorting for views, so it would be OK to do some  
normalization on-the-fly on Ruby land, and since the same criteria  
has to be used throughout the application I was thinking on some sort  
of generator whose usage would be:

   class User < ActiveRecord::Base
     normalize_for_sorting :surname
   end

The intention is not to modify surname, we need it in the views,  
normalize_for_sroting would generate a method  
User#surname_for_sorting and configure it as a creation/finding  
filter that applies the necessary tr///. The aim is:

   * We normalize the strings once and store them in
     attributes instead of applying the normalizer
     in all sort blocks

   * The tr///, the configuration of filters, etc. is
     written in one place, following DRY.

I think that can be done, but I am not fluent enough yet in Rails to  
determine whether it is a clean solution, and how to implement it in  
an idiomatic way. Any advices?

-- fxn

How about modifying your data before putting it in the database??
That''s
how i do the "trick".

==class User < ActiveRecord::Base

  def before_save
    self.surname_for_sorting = normalize_for_sorting :surname
  end
end
==
or.. if you don''t want extra data in the db, and format it for every 
request.

==class User < ActiveRecord::Base

  def surname_for_sorting
    @sfs = normalize_for_sorting(:surname) if !@sfs
    @sfs
  end
end
==
If you desperately want more DRY, make it a mixin.

-- 
Posted via http://www.ruby-forum.com/.

On Feb 19, 2006, at 22:53, Colin wrote:
> or.. if you don''t want extra data in the db, and format it for
every
> request.
>
> ==> class User < ActiveRecord::Base
>
>   def surname_for_sorting
>     @sfs = normalize_for_sorting(:surname) if !@sfs
>     @sfs
>   end
> end
> ==>
> If you desperately want more DRY, make it a mixin.
What I have in mind is: a class method for models that generates  
_for_sorting accessors on-the-fly based on parameters, and that  
creates callbacks after_(save|find) that initialize those attributes.

I guess class_eval is all what I need, but which is the idiomatic way  
to define normalize_for_sorting so that is visible in all models? Do  
I open ActiveRecord::Base and add the method? If that''s the way,  
where do I do that? In which file?

-- fxn