A database transaction yana haɗa ayyuka da yawa domin suna iya samun nasara duka ko kuma suka gazawa tare (atomicity) — yana hana karamin, state da ba daidai ba. Django ta ba da transaction.atomic domin lullubar ayyuka a cikin transaction, yana tabbatar da data integrity don ayyukan mataki da yawa.
():
from_account.balance -= amount
from_account.save()
to_account.balance += amount
to_account.save()
Ba tare da transaction, idan aiki na biyu ya gazawa, na farko ya riga ya gajiya — barin database a cikin broken, state da ba daidai ba (kuɗi ya baje amma ba'a ba sa creditin).
from django.db import transaction
# as a context manager
def transfer_money(from_account, to_account, amount):
with transaction.atomic(): # everything inside is ONE transaction
from_account.balance -= amount
from_account.save()
to_account.balance += amount
to_account.save()
# if ANY operation raises an exception, the WHOLE block is ROLLED BACK
# → either both saves happen, or neither does (atomicity)
# or as a decorator on a whole function/view
@transaction.atomic
def create_order(request):
order = Order.objects.create(...)
for item in items:
OrderItem.objects.create(order=order, ...)
# all-or-nothing: a failure anywhere rolls back the entire order creation
A cikin atomic(), idan aiki daya ya taso exception, Django yana maimaita kowane canji a cikin block — saboda haka database ba ta taɓa jiya half-updated. A kan nasara, duka canje suna gajiya tare.
with transaction.atomic(): # outer transaction
do_something()
try:
with transaction.atomic(): # inner = a SAVEPOINT
risky_operation()
except Exception:
pass # inner rolls back to the savepoint; outer continues
Nested atomic blocks suna amfani da savepoints — inner block na iya maimaita kai tsaye ba tare da bugi duka waje transaction.
✓ Catch exceptions OUTSIDE the atomic block (catching inside can break rollback handling)
✓ select_for_update() locks rows within a transaction (prevent race conditions on updates)
with transaction.atomic():
account = Account.objects.select_for_update().get(pk=id) # row locked until commit
✓ ATOMIC_REQUESTS setting wraps EVERY request in a transaction (per-database)
✓ Keep transactions SHORT — long transactions hold locks, hurting concurrency
Database transactions suna da mahimmanci ga data integrity duk lokacin da aiki ya haɗa ayyuka da yawa masu alaka na database waɗanda dole su samun nasara ko gazawa a matsayin gida — kuma fahimtar transaction.atomic ita ce mahimmancin ilmi don gina aiki da gare, alkalisai na aminci. Matsalar mahimmanta da transactions ke warware ita ce karamin gazawa: ba tare da atomicity, idan aiki na mataki da yawa ya gazawa tsakai (tarowa, exception, constraint violation), database ta jiya a cikin state da ba daidai ba — misalin classic kuɗi-jujjuya (baje daga asusun ɗaya amma ba credit ga ɗayan) yana nuna yadda wannan yana lalata data kuma na iya samun mahimmancin sakamakon. transaction.atomic ta ba da tabbaci cewa ayyuka sune duka ko babu (maimaita duka block a kan kuka daya), wanda ya zama dole ga kuka daya wanda ke baje abubuwa da yawa — yin odari tare da sassan layin, jujjuya kuɗi, sabunta mahimmancin rikodin — domin kula da consistent database.
Fahimtar yadda ake amfani da atomic blocks (a matsayin context manager ko decorator), nested transactions tare da savepoints, da mahimmancin bayyani — kama exception a waje na block, amfani da select_for_update() domin kulle layuka da hana rikitarwa a cikin updates na lokaci gida, da kiyaye transactions gajere domin hana riƙe locks — ita ce fahimtar aiki don gina aikace-aikace masu karfi. Data consistency wani mahimmancin buɗaɗɗen banaji ne na ingantattun tsarin, kuma transactions sune tsarin da ke tabbatar da ita ga ayyuka na mataki da yawa na database, yana sa wannan mahimmancin jigon wanda ya bambanta masu ƙori da jajjifa gida, code na integrity-marcar daga waɗanda aikace-aikacen su na iya shireyi lalata data a cikin yanayin gazawa ko haɗin gida — mahimmancin alagmat a cikin kowane aikace-aikace da ke bada hanya mahimmancin, data canji masu alaka.