Rails - Jul 2006 - creating a computed column with activerecord for to_xml

Hi. I have a question about activerecord, computed columns and to_xml. 
I have a simple model called person that has a first_name and a 
last_name field (and thus a first_name and last_name field in the Person 
table).  When I :find a model and call to_xml, I would like the result 
to not only send back first name and last name as xml but also add an 
additional attribute called full_name that is "last_name, first_name" 
I
would like to put this logic in my model.  I have made a def that 
returns this in the model - so you can call theperson.fullname in the 
console and it will return last_name, first_name. However, I would like 
to_xml to do this also.  This is basically the concept of a computed 
column.  I tried adding to the column hash in Person and many other 
ideas but nothing works. Can anyone help with this?  Thanks very much.

Ritz

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

Ritz Coder wrote:
> Hi. I have a question about activerecord, computed columns and to_xml. 
[...snip details...]

You could simply add the "computed" column to your database and then
use
a "before_save" callback to compute this value. Only downside is that 
unsaved records would have NULL for full_name when doing to_xml. You 
could even get around this through additional code.

Eric