Non-atomic Operation

non-atomic.py

# atomic blocks can be nested. In this case, when an inner block completes successfully, 
# its effects can still be rolled back if an exception is raised in the outer block at a later point.
#############################################################################
# atomic is usable both as a decorator:
from django.db import transaction
@transaction.atomic
def viewfunc(request):
    # This code executes inside a transaction.
    do_stuff()
#############################################################################
# and as a context manager:
from django.db import transaction
def viewfunc(request):
    # This code executes in autocommit mode (Django's default).
    do_stuff()
    with transaction.atomic():
        # This code executes inside a transaction.
        do_more_stuff()
#############################################################################
# Wrapping atomic in a try/except block allows for natural handling of integrity errors:
from django.db import IntegrityError, transaction
@transaction.atomic
def viewfunc(request):
    create_parent()
    try:
        with transaction.atomic():
            generate_relationships()
    except IntegrityError:
        handle_exception()
    add_children()
#############################################################################