Rails - Aug 2005 - How to give a model default values / setup?

I''m trying to initialize an AR model with some default values  
(populating it and some other models when the first model is  
created). I''ve tried putting the code in the model''s
initialize
function, to no avail. Right now I have:

# (app/models/event.rb)

   def initialize
     Event.transaction do
       max_item = Event.find(:first, :order => "list_order DESC")
       max_num = 0
       if max_item
         max_num = max_item.list_order
       end
       list_order = max_num + 1
     end

     super

     unless args = []
       default_seat_groups
     end
   end

####################
This throws various errors on trying to save the model.

default_seat_groups is the method that sets up an associated model  
(seat_group belongs_to :event). I haven''t been able to find docs on  
the best way to initialize a model with arbitrary code. Am I thinking  
about this the wrong way?

Thanks!
--
Brad Ediger
866-EDIGERS

Hello Brad,

The way I do it is:
def initialize(args=[])
   super(args)

   # Default values, but only if not already initialized
   self.category = Category.default if self.category.blank?
end

You can''t access an object''s attributes until super''s
been called,
because super will query the DB table (SHOW FIELDS FROM model) and only 
subsequently will make the accessors available.

In your specific case though, I don''t see why it doesn''t work.
What
errors do you get ?

Hope that helps,
François


Brad Ediger said the following on 2005-08-29 20:45:
> I''m trying to initialize an AR model with some default values  
> (populating it and some other models when the first model is  created). 
> I''ve tried putting the code in the model''s initialize 
function, to no
> avail. Right now I have:

François,
Thanks for your help. Here''s what I have now:

   def initialize(args=[])
     super(args)

     # Assign list order
     Event.transaction do
       max_item = Event.find(:first, :order => "list_order DESC")
       max_num = 0
       if max_item
         max_num = max_item.list_order
       end
       list_order = max_num + 1
     end

     unless args == []
       default_seat_groups
     end
   end

The error this gives me is:

NoMethodError in Events#new

undefined method `stringify_keys!'' for []:Array

That error happens on the super(args) line. I''ve been getting various  
errors throughout this, but I can''t seem to figure out anything  
meaningful. It occurs when accessing localhost:3000/events/new to  
create a new event.

Thanks again,
Brad


On Aug 31, 2005, at 8:17 AM, François Beausoleil wrote:
> Hello Brad,
>
> The way I do it is:
> def initialize(args=[])
>   super(args)
>
>   # Default values, but only if not already initialized
>   self.category = Category.default if self.category.blank?
> end
>
> You can''t access an object''s attributes until
super''s been called,
> because super will query the DB table (SHOW FIELDS FROM model) and  
> only subsequently will make the accessors available.
>
> In your specific case though, I don''t see why it doesn''t
work.
> What errors do you get ?
>
> Hope that helps,
> François
>
>
> Brad Ediger said the following on 2005-08-29 20:45:
>
>> I''m trying to initialize an AR model with some default values
>> (populating it and some other models when the first model is   
>> created). I''ve tried putting the code in the model''s
initialize
>> function, to no avail. Right now I have:
>>
>
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>


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Oh my, I''m sorry, I did a booboo...

Brad Ediger said the following on 2005-09-01 14:52:
>   def initialize(args=[])
>     super(args)
> *NoMethodError in Events#new*
That should have been:
def initialize(args={})
   # code
end

Notice we receive a Hash, not an Array.

Why oh why didn''t I just copy some code over ?  Must be all that DRY 
stuff from the PragProg and RoR :)

Bye !
François

Aah -- that''s right!

Anyway, I made that same mistake independently (Array instead of  
Hash) when I was trying to fix things.

I''ll try it out!

Thanks,
be


On Sep 2, 2005, at 7:24 AM, François Beausoleil wrote:
>
> That should have been:
> def initialize(args={})
>   # code
> end
>
> Notice we receive a Hash, not an Array.
>
> Why oh why didn''t I just copy some code over ?  Must be all that  
> DRY stuff from the PragProg and RoR :)