Rails - Nov 2010 - Accessing relationships during call backs

I have an encrypted field that uses a before_save (etc) callback to
accomplish the field encryption. It works right now with one key for
the application.

I have a model where users belong to groups (groups have many users)
and each group has a unique key. I want to grab the group "key" during
the callback. When I try to add "key = model.group.key", I get an
error: NoMethodError: undefined method `key'' for nil:NilClass

I assumed that the "model" would resolve to the user model and that I
could follow the relation into group and grab the "key". I works in
the console by hand once I assign the find results to a variable.

      def before_save(model)
        unless model[@field].blank?
          key = model.class.encryption_key
          goo = model.group.key # see if I can see the "key"
          Rails.logger.debug("group key: #{goo}") # log it
          model[@field] = encrypt(model[@field], key, @options)
        end
      end

I can get the proper text by using:

goo = Group.find(model[''group_id'']).key

Is there a "cleaner" way to express this?

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On Fri, Nov 5, 2010 at 9:57 AM, dwormuth
<dwormuth-cIpcPs7DjqbWs/AcZQh2Cw@public.gmane.org> wrote:
> I have an encrypted field that uses a before_save (etc) callback to
> accomplish the field encryption. It works right now with one key for
> the application.
>
> I have a model where users belong to groups (groups have many users)
> and each group has a unique key. I want to grab the group "key"
during
> the callback. When I try to add "key = model.group.key", I get an
> error: NoMethodError: undefined method `key'' for nil:NilClass
>
> I assumed that the "model" would resolve to the user model and
that I
> could follow the relation into group and grab the "key". I works
in
> the console by hand once I assign the find results to a variable.
>
>      def before_save(model)
>        unless model[@field].blank?
>          key = model.class.encryption_key
>          goo = model.group.key # see if I can see the "key"
>          Rails.logger.debug("group key: #{goo}") # log it
>          model[@field] = encrypt(model[@field], key, @options)
>        end
>      end
>
> I can get the proper text by using:
>
> goo = Group.find(model[''group_id'']).key
>
> Is there a "cleaner" way to express this?

You should be using self instead of model.


-- 
Erol M. Fornoles
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