Question

This is my model:

class People(models.Model):
    name = models.CharField(max_length=100)
    lastname = models.CharField(max_length=100)

In views.py

-When I try this one to count empty lastname fields:

People.objects.filter(lastname__isnull=True).count()

It returns always 0 event though there are some empty lastname fields.

Why I am getting 0, is there any problem with my code or Is there any other way to count empty fields in a table?

Answer 1

Your CharField is most likely storing empty strings, not NULL

Django docs on null field value

Field.null
If True, Django will store empty values as NULL in the
database. Default is False.

Note that empty string values will always get stored as empty strings,
not as NULL. Only use null=True for non-string fields such as
integers, booleans and dates. For both types of fields, you will also
need to set blank=True if you wish to permit empty values in forms, as
the null parameter only affects database storage (see blank).

Avoid using null on string-based fields such as CharField and
TextField unless you have an excellent reason. If a string-based field
has null=True, that means it has two possible values for “no data”:
NULL, and the empty string. In most cases, it’s redundant to have two
possible values for “no data;” Django convention is to use the empty
string, not NULL.

Try changing your query to:

People.objects.filter(lastname="").count()

Empty is not the same as NULL. You would have needed to set your fields to have null=True, which as the docs suggest, is not recommended for a CharField.