Charfield not enforcing null constraint

Using Django Using the ORM
1

Expected behvaior: A django.db.utils.IntegrityError: NOT NULL constraint failed to be raised.

Current behvaior: An intance with an empty string as it’s value is created.

Django version=5.0.4,
Database backend: sqlite3

My model:

class Product(models.Model):
    name = models.CharField(max_length=55)
    description = models.TextField()

When I try mking an instance without specifying name and description I get no error.

product = Product()
product.save() # no error raised, No difference using Product.objects.create()

I have tried checking the DB manually and the constaint is present and works if I try to create an instance outside of Django but if it is done using Django no error is raised and the value for the field is an empty string.

2

Normally if you are trying to validate the model instance, you would call instance.full_clean() and that would generate a ValidationError with the given fields.
But on your case it maybe creating the values as blank string on the database.

3

Yes I understand that I can take it into validation level but I don’t understand the inconsistency since null=False would behave the same and raise an IntegrityError for all fields except Charfield and Textfield.

4

Check the null documentation.

Django’s default behavior is to allow empty strings ('' ) for CharField and TextField fields.

Try this to set explicitly the null and blank options:

class Product(models.Model):
    name = models.CharField(max_length=55, blank=False, null=False)
    description = models.TextField(blank=False, null=False)
5

Also for additional information on this, see: get_or_create() and create() with unspecified non-nullable fields - #7 by KenWhitesell

1 Like
6

Have tried this. No migrations change is detected and the behavior is still the same in the save method.

7

Thank you. Yes appreantly passing None explicitly will raise the expected error but not setting a value will default to an empty string which is allowed. The decision to set an empty string as the default value doesn’t make much sense to me.

8

if you want run valid before save object, you should call model.full_clean() as leandrodesouzadev said.

if you do not call full_clean, django do not run validate.

obj = model()
obj.full_clean()
obj.save()

Note, however, that like Model.full_clean(), a model’s clean() method is not invoked when you call your model’s save() metho