Rails - Dec 2004 - Referencing a table''s fields.

Hello,

I recently set up a rails application, and wanted to provide helper methods in
my model class.
I was confused that the class DOESN''T refer to its fields as instance
variables.  I merely had to
type in the field names to be able to work with their data.

Here''s an example:

I have a "Chessgame" class with a begindate and an enddate.  To get
the number of hours that the
game took, I wrote an "hours" method in the Chessgame class.  I
thought that i would reference the
begindate and enddate field as instance variables, but this did not work.  I had
to write the code
like this:
-------------------------------------------------
require ''active_record''
class Chessgame < ActiveRecord::Base
  def hours
    (enddate - begindate) / 60 / 60  # Why no "@" sign in front of
begindate & enddate?
  end
end
--------------------------------------------------
Why don''t the enddate & begindate fields show up in my class as
instance variables?
When I prefix the variables with an "@", then I get this message:
"NoMethodError in Chessgame#list"

Thanks,

--Nate

Nathan Neff wrote:
> Why don''t the enddate & begindate fields show up in my class
as instance variables?
Because enddate and begindate are not real variables. They are methods 
on the object that are created on the fly by rails. There are no 
attributes except the ones that you create (and those are not persisted 
to the database).

Eric


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