models.DateField(null=True, blank=True) accepts None, but not the empty string ''

[shmengie]

For some reason I cannot create a record with

class MyModel(models.Model):
    models.DateField(null=True, blank=True)
MyModel(MyDateField='')  

It must be either None or a valid date.

[mrts]

The problem is that DateField.to_python() (or DateTimeField) doesn't treat '' specially, see source:/django/trunk/django/db/models/fields/__init__.py@10545#L464

class DateTest(models.Model):
    foo = models.DateField(null=True, blank=True)

>>> d = DateTest(foo='')
>>> d.save()
Traceback (most recent call last):
  ...
  File "/usr/lib/python2.6/dist-packages/django/db/models/fields/__init__.py", line 474, in to_python
    _('Enter a valid date in YYYY-MM-DD format.'))
ValidationError: Enter a valid date in YYYY-MM-DD format.

[Deepak]

blank=True tells user that they don't have to fill this field, and it doesn't mean that its empty string. Django assign NoneType if empty.

[Karen Tracey]

Replying to mrts:

The problem is that DateField.to_python() (or DateTimeField) doesn't treat '' specially...

Neither does IntegerField nor FloatField, eg. It's not clear to me why Date fields would/should be singled out for special treatment here. Forms fields consistently handle treating empty strings input as None, but if you are operating at the model level then you need to use None when you mean None, not an empty string.