django query exists code example

Example 1: pass in queryset as filter django

users = UserClasses.objects.filter(class_id=data['class_id'])
user_details = User.objects.filter(id__in=users.values_list('id', flat=True))

Example 2: django queryset exists

if some_queryset.exists():
    print("There is at least one object in some_queryset")

Example 3: django filter exsist

if table.objects.filter(prop='value').count() > 0:

Example 4: django 3.0 queryset examples

>>> Entry.objects.filter(
...     headline__startswith='What'
... ).exclude(
...     pub_date__gte=datetime.date.today()
... ).filter(
...     pub_date__gte=datetime.date(2005, 1, 30)
... )

Example 5: django queryset count

# Returns the total number of entries in the database.
Entry.objects.count()

# Returns the number of entries whose headline contains 'Lennon'
Entry.objects.filter(headline__contains='Lennon').count()