django annotate code example

Example 1: django group by

# If you mean to do aggregation you can use the aggregation features of the ORM:
from django.db.models import Count
Members.objects.values('designation').annotate(dcount=Count('designation'))

# This results in a query similar to:
SELECT designation, COUNT(designation) AS dcount
FROM members GROUP BY designation

#and the output would be of the form
[{'designation': 'Salesman', 'dcount': 2}, 
 {'designation': 'Manager', 'dcount': 2}]

Example 2: objects.filter django

>>> Entry.objects.filter(blog_id=4)

Example 3: django queryset exists

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

Example 4: django filter values with OR operator

Blog.objects.filter(pk__in=[1, 4, 7])

Example 5: 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)
... )