Rails - May 2006 - ActiveRecord: When / where to validate data? Tricky question

First of all, thanks for you time. I have kind of a tricky question and 
wanted to see what you guys thought.

-------------------------------------------
Lets say I have this:
-------------------------------------------
class Purchase < ActiveRecord::Base
  validates_numericality_of :some_number, :only_integer => true
end

-------------------------------------------
Then I do this:
-------------------------------------------
purchase = Purchase.new
purchase.some_number = ''This is not a number''

Right now the data is not correct. Is this ok? Why should I even let 
invalid data like this get put into the some_number attribute? So my 
question is this...

-------------------------------------------
Is this better?
-------------------------------------------
Instead of doing:
validates_numericality_of :some_number, :only_integer => true

Doesn''t it make more sense to validate the data as it''s being
set and if
it''s not correct raise an exception? This way its not even possible to 
get valid data into this attribute, which renders the statement 
(validates_numericality_of :some_number, :only_integer => true) 
unnecessary.

If you dig deeper I guess the real question is, will I ever use 
purchase.some_number when its not pulled directly out of the db?


Any help is greatly appreciated.

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

Hi Ben,

I think you make some good points, but I also think that the style of
programming rails would need to change a lot for this to work.

for eg if what your suggesting occurs I could not, in response to a form do

Mymodel.new( params[:my_model] )
without wrapping it in a begin rescue, which isn''t that bad, but...

In my view template I could no longer call error_messages_for and get a full
list of errors to feed back to the user since it would stop processing the
validation as soon as one failed.

Similarly what would happen with
@my_model.update_attributes( params[:my_model])  ?  My guess is something
similar.

I don''t think I would like this.

Having said that if you wanted to do this you could roll your own as a
plugin.

On 6/1/06, Ben Johnson <bjohnson@mediamanifest.com>
wrote:
>
> First of all, thanks for you time. I have kind of a tricky question and
> wanted to see what you guys thought.
>
> -------------------------------------------
> Lets say I have this:
> -------------------------------------------
> class Purchase < ActiveRecord::Base
>   validates_numericality_of :some_number, :only_integer => true
> end
>
> -------------------------------------------
> Then I do this:
> -------------------------------------------
> purchase = Purchase.new
> purchase.some_number = ''This is not a number''
>
> Right now the data is not correct. Is this ok? Why should I even let
> invalid data like this get put into the some_number attribute? So my
> question is this...
>
> -------------------------------------------
> Is this better?
> -------------------------------------------
> Instead of doing:
> validates_numericality_of :some_number, :only_integer => true
>
> Doesn''t it make more sense to validate the data as it''s
being set and if
> it''s not correct raise an exception? This way its not even
possible to
> get valid data into this attribute, which renders the statement
> (validates_numericality_of :some_number, :only_integer => true)
> unnecessary.
>
> If you dig deeper I guess the real question is, will I ever use
> purchase.some_number when its not pulled directly out of the db?
>
>
> Any help is greatly appreciated.
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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