[django] How to filter empty or NULL names in a QuerySet?

I have first_name, last_name & alias (optional) which I need to search for. So, I need a query to give me all the names that have an alias set.

Only if I could do:

Name.objects.filter(alias!="")

So, what is the equivalent to the above?

Firstly, the Django docs strongly recommend not using NULL values for string-based fields such as CharField or TextField. Read the documentation for the explanation:

https://docs.djangoproject.com/en/dev/ref/models/fields/#null

Solution: You can also chain together methods on QuerySets, I think. Try this:

Name.objects.exclude(alias__isnull=True).exclude(alias="")

That should give you the set you're looking for.

this is another simple way to do it .

Name.objects.exclude(alias=None)

You can simply do this:

Name.objects.exclude(alias="").exclude(alias=None)

It's really just that simple. filter is used to match and exclude is to match everything but what it specifies. This would evaluate into SQL as NOT alias='' AND alias IS NOT NULL.

To avoid common mistakes when using exclude, remember:

You can not add multiple conditions into an exclude() block like filter. To exclude multiple conditions, you must use multiple exclude()

Example

Incorrect:

User.objects.filter(email='[email protected]').exclude(profile__nick_name='', profile__avt='')

Correct:

User.objects.filter(email='[email protected]').exclude(profile__nick_name='').exclude(profile__avt='')

From Django 1.8,

from django.db.models.functions import Length

Name.objects.annotate(alias_length=Length('alias')).filter(alias_length__gt=0)

Name.objects.filter(alias__gt='',alias__isnull=False)