Rails - Mar 2006 - STI, subclasses and callbacks

I have a STI class tree. I want to set some default values (calculated 
values so I can''t set it in the database as defaults) on every created 
instance regardless of what subclass is actually instantiated. So I 
figured adding a after_create callback in the top class in the hierarchy 
should do the trick. It seems it doesn''t get called :(

Code:
class SuperClass < ActiveRecord::Base
...
   after_create :set_defaults
...
   private
   def set_defaults
     puts "Setting defaults #{id}"
     ... set values ...
     save()
   end
end

Am I doing something wrong here?

/Marcus

I tried this one (that worked but it''s not very pretty...)

   def SuperClass.inherited(sub_class)
     ...
     sub_class.class_eval <<-EOS
       after_create { |node| ... set defaults ... ; node.save }
     EOS
     ...
   end

I''m doing work in the inherited department anyway so it''s not
that bad.
But I thought that callbacks should work over subclasses. Don''t they?

/Marcus

On 3/1/06, marcus <m-lists@bristav.se> wrote:
> I tried this one (that worked but it''s not very pretty...)
>
>    def SuperClass.inherited(sub_class)
>      ...
>      sub_class.class_eval <<-EOS
>        after_create { |node| ... set defaults ... ; node.save }
>      EOS
>      ...
>    end
>
> I''m doing work in the inherited department anyway so it''s
not that bad.
> But I thought that callbacks should work over subclasses. Don''t
they?
>
> /Marcus
It''s a slightly tricky subject, but I go over it on my blog:

http://weblog.techno-weenie.net/2006/2/21/unitialized-constant-technoweenie

Quick tips:

- don''t override self.inherited
- put validations/callbacks ABOVE associations (especially in Rails 1.0)


--
Rick Olson
http://techno-weenie.net

Rick Olson skrev:
> It''s a slightly tricky subject, but I go over it on my blog:
> 
> http://weblog.techno-weenie.net/2006/2/21/unitialized-constant-technoweenie
How does this article relate to the subject? I see you mention STI there 
but it''s in the context of Reloadable classes.
> Quick tips:
> 
> - don''t override self.inherited
Why? Is Rails doing something there as well? How do I do if I want to do 
something like generate methods based on my own conventions when 
subclassed (in this particular class hierarchy)?
> - put validations/callbacks ABOVE associations (especially in Rails 1.0)
Okay, I''ll try that.

Thanks

/Marcus

On 3/1/06, marcus <m-lists@bristav.se> wrote:
>
> Rick Olson skrev:
> > It''s a slightly tricky subject, but I go over it on my blog:
> >
> >
http://weblog.techno-weenie.net/2006/2/21/unitialized-constant-technoweenie
>
> How does this article relate to the subject? I see you mention STI there
> but it''s in the context of Reloadable classes.
>
> > Quick tips:
> >
> > - don''t override self.inherited
>
> Why? Is Rails doing something there as well? How do I do if I want to do
> something like generate methods based on my own conventions when
> subclassed (in this particular class hierarchy)?
>
> > - put validations/callbacks ABOVE associations (especially in Rails
1.0)
>
> Okay, I''ll try that.
>
> Thanks
>
> /Marcus
Ha, I''m sorry, wrong article.  THIS one is the one i was thinking of:

http://weblog.techno-weenie.net/2006/2/15/activerecord-callbacks-and-sti

It explains the self.inherited bit.

--
Rick Olson
http://techno-weenie.net