Rails - Mar 2006 - Model attributes that are not backed by persistent storage

I have a model object that I would like to add an attribute to.

It''s an array of other objects.

If I do

  attr_accessor :local_image_tags

should I then be able to assign to object.local_image_tags or read from 
object.local_image_tags without incident?

Is ActiveRecord going to assume that there is a table behind these guys?
If so, how do I indicate that these attributes are not stored?

Thanks,
Wes

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On Tue, Mar 28, 2006 at 09:34:09PM +0200, Wes Gamble
wrote:
> I have a model object that I would like to add an attribute to.
> 
> It''s an array of other objects.
> 
> If I do
> 
>   attr_accessor :local_image_tags
> 
> should I then be able to assign to object.local_image_tags or read from 
> object.local_image_tags without incident?
> 
> Is ActiveRecord going to assume that there is a table behind these guys?
No.  ActiveRecord *knows* what fields are in the table that underlies the
object, it doesn''t need to assume anything.  Besides, the mechanics of
attributes-as-fields is completely different to attr_accessors.
> If so, how do I indicate that these attributes are not stored?
You don''t.  AR knows all about the table and it''s structure,
and will ignore
any new and shiny instance attributes you may care to play with.

- Matt