Re: A question about Model.full_clean

On 01/06/12 14:47, David Markey wrote:

Hi All,

Say I have this model

class TestModel(models.Model):

    my_test = models.CharField(max_length=512, blank=True)

And I try this:

In [1]: from core.base.models import TestModel

In [2]: test_model = TestModel()

In [3]: test_model.my_test = ""

In [4]: test_model.full_clean()

In [5]: test_model.save()

Ok cool, this is expected.

How about:

In [6]: test_model2 = TestModel()

In [7]: test_model2.my_test = None

In [8]: test_model2.full_clean()

In [9]: test_model2.save()

##IntegrityError raised

Is there a way for full_clean() to catch that the "my_test" field is Null when it shouldn't be, when blank=True?

If I have blank=False, it wont validate when my_test="".

I think the behaviour is explained by the clean_fields method called by full_clean:

        for f in self._meta.fields:
            if f.name in exclude:
                continue
            # Skip validation for empty fields with blank=True. The developer
            # is responsible for making sure they have a valid value.
            raw_value = getattr(self, f.attname)
            if f.blank and raw_value in validators.EMPTY_VALUES:
                continue

https://github.com/django/django/blob/master/django/db/models/base.py#L851

I can't think of a way for you to avoid checking for whether test_model2.my_test is None. Can you change the code that is assigning test_model2.my_test = None? The default value for the CharField is the empty string, which as you show in your first example, doesn't cause a problem.

Cheers,
Alasdair

--   Alasdair Nicol  Developer, MEMSET    mail: alasdair@memset.com    web: http://www.memset.com/     Memset Ltd., registration number 4504980. 25 Frederick Sanger Road, Guildford, Surrey, GU2 7YD, UK.