Nullable ChoiceField on ModelForm - has_changed always True

[steve byerly]

I have a model with a nullable field (PositiveSmallIntegerField) with defined choices. When I make a ModelForm for the model and do not select a value for this field, the field always comes back in the changed data. The reason is that the empty choice value, the data_value, is an empty string, while the initial_value is None.

I can override the base field and make a TypedChoiceField, and provide a function to coerce which returns None if the value is an empty string.

Is this the only route, or is there a better way to accomplish this?

[steve byerly]

Also of note, I recently upgraded to Django 1.9 from Django 1.7 where this was working fine. It looks like this commit is the cause of my problem:

https://github.com/django/django/commit/ff077cd6496b6f82195e2dc040f70e19e7c206c9

[steve byerly]

It actually looks like the commit fixed the regression and was in 1.9.1. Didn't realize it had been released.

[James Schneider]

On Tue, Jan 19, 2016 at 4:45 PM, steve byerly <sbye...@gmail.com> wrote:

Also of note, I recently upgraded to Django 1.9 from Django 1.7 where this was working fine. It looks like this commit is the cause of my problem:

https://github.com/django/django/commit/ff077cd6496b6f82195e2dc040f70e19e7c206c9

Is there any mention of a behavior change in the release notes between those versions? If you can come up with a simple example case, I would recommend filing a ticket about the behavior change, or posting this to the django-dev mailing list. 

Looks like this ticket is related: https://code.djangoproject.com/ticket/25942 as was noted in the diff you linked above.

-James