Model attributes that are not backed by persistent storage


#1

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


#2

On Tue, Mar 28, 2006 at 09:34:09PM +0200, Wes G. wrote:

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