with transaction.atomic():

`with transaction.atomic():` is a Python context manager that ensures that a group of database operations are executed as a single transaction. It's commonly used in Django web applications to ensure that database changes are atomic and consistent.

When `with transaction.atomic():` is used, all the database operations inside the block will either be committed together if all operations are successful, or rolled back if any operation fails. This is useful to maintain data integrity and consistency in the face of errors or exceptions.

For example, suppose you have a Django view that needs to update two models, `ModelA` and `ModelB`. You can use `with transaction.atomic():` to ensure that both updates are either committed or rolled back together:

from django.db import transaction
from myapp.models import ModelA, ModelB

@transaction.atomic
def my_view(request):
    try:
        a = ModelA.objects.get(id=1)
        b = ModelB.objects.get(id=2)
        a.field = 'new value'
        b.field = 'new value'
        a.save()
        b.save()
    except Exception as e:
        # Handle exception
        pass

In this example, if either `a.save()` or `b.save()` raises an exception, both updates will be rolled back and the database will remain unchanged.