Hi Everyone,
I'd like to propose a small change to django.db.models.Model to make
it neater to determine whether or not a model object is already stored
in the database. Either:
Option 1: Rename the _get_pk_val() method to get_pk_val(), marking it
safe for public use.
Option 2: Add a method named is_saved() which checks the value of the
primary key.
Here's the situation that inspired the proposal. I'm in the midst of
some code to push objects in and out of custom FormManipulators. At
several points, the code needs to determine whether or not the model
objects are stored in the database, in order to know whether the
object should be deleted.
Since my model classes don't explicitly define primary keys, this is
fairly simple - it's just a matter of checking model_object.id. Since
I was doing it several times, I made up a utility method,
"is_saved(model_object)". I now have this kind of code:
if is_saved(object):
object.delete()
However, that doesn't look right - model objects know whether or not
they've been saved, and should be able to communicate that without
requiring the programmer to know the primary key name.
I would have used django.db.models.Model._get_pk_val() method, except
for the leading underscore marking the method as being for private
use. Hence the first option, at the top of this email.
If exposing the primary key value like that would be undesirable, a
more modest option would be a simple "is_saved()" method.
Does either of these options sound reasonable? If so, I'm happy to
make up a patch, including changes to db-api.txt.
Alan.
--
Alan Green
[EMAIL PROTECTED] - http://bright-green.com
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