On Thu, Jan 12, 2012 at 7:40 PM, Tai Lee <real.hu...@mrmachine.net> wrote:
> class Profile(models.Model):
> first_name = models.CharField(blank=True, max_length=50)
> last_name = models.CharField(blank=True, max_length=50)
> address = models.CharField(blank=True, max_length=50)
>
> class ProfileForm(ModelForm):
> class Meta:
> model = Profile
>
> profile = Profile.objects.create(first_name='Tai', last_name='Lee',
> address='Sydney')
> form = ProfileForm({}, instance=profile)
> if form.is_valid():
> form.save()
> }}}
>
> The profile will have no first name, last name or address. The form
> will produce no validation errors and will save the updated model to
> the database.
>
> This is very surprising and counter-intuitive to me.
The ultimate solution is: don't use model forms. I never use them for
anything, precisely because of things like this, where the framework
is trying to do too much behind the scenes. It's too magical for my
tastes, and while I understand why we added it to the framework, I see
it as a crutch for lazy developers. C'mon, it's not a lot of work to
create a "normal" (non-model) form class and pass its cleaned data to
a model's save() method.
End rant. :-)
Thanks for writing out this example, Tai. I disagree and do not see it
as counterintuitive. The "ProfileForm({}, instance=profile)" is
clearly passing in empty data (the empty dictionary), and it makes
sense that Django would see the empty data, then determine that empty
data is allowed on the fields (blank=True) and set those fields to
empty data. If you want to avoid this, you have two options: don't use
"blank=True," or don't use a model form.
Adrian
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