mirror of
https://github.com/django/django.git
synced 2024-11-18 15:34:16 +00:00
212ee65be7
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5803 bcc190cf-cafb-0310-a4f2-bffc1f526a37
100 lines
3.2 KiB
Python
100 lines
3.2 KiB
Python
"""
|
|
15. Transactions
|
|
|
|
Django handles transactions in three different ways. The default is to commit
|
|
each transaction upon a write, but you can decorate a function to get
|
|
commit-on-success behavior. Alternatively, you can manage the transaction
|
|
manually.
|
|
"""
|
|
|
|
from django.db import models
|
|
|
|
class Reporter(models.Model):
|
|
first_name = models.CharField(max_length=30)
|
|
last_name = models.CharField(max_length=30)
|
|
email = models.EmailField()
|
|
|
|
def __unicode__(self):
|
|
return u"%s %s" % (self.first_name, self.last_name)
|
|
|
|
__test__ = {'API_TESTS':"""
|
|
>>> from django.db import connection, transaction
|
|
"""}
|
|
|
|
from django.conf import settings
|
|
|
|
building_docs = getattr(settings, 'BUILDING_DOCS', False)
|
|
|
|
if building_docs or settings.DATABASE_ENGINE != 'mysql':
|
|
__test__['API_TESTS'] += """
|
|
# the default behavior is to autocommit after each save() action
|
|
>>> def create_a_reporter_then_fail(first, last):
|
|
... a = Reporter(first_name=first, last_name=last)
|
|
... a.save()
|
|
... raise Exception("I meant to do that")
|
|
...
|
|
>>> create_a_reporter_then_fail("Alice", "Smith")
|
|
Traceback (most recent call last):
|
|
...
|
|
Exception: I meant to do that
|
|
|
|
# The object created before the exception still exists
|
|
>>> Reporter.objects.all()
|
|
[<Reporter: Alice Smith>]
|
|
|
|
# the autocommit decorator works exactly the same as the default behavior
|
|
>>> autocomitted_create_then_fail = transaction.autocommit(create_a_reporter_then_fail)
|
|
>>> autocomitted_create_then_fail("Ben", "Jones")
|
|
Traceback (most recent call last):
|
|
...
|
|
Exception: I meant to do that
|
|
|
|
# Same behavior as before
|
|
>>> Reporter.objects.all()
|
|
[<Reporter: Alice Smith>, <Reporter: Ben Jones>]
|
|
|
|
# With the commit_on_success decorator, the transaction is only comitted if the
|
|
# function doesn't throw an exception
|
|
>>> committed_on_success = transaction.commit_on_success(create_a_reporter_then_fail)
|
|
>>> committed_on_success("Carol", "Doe")
|
|
Traceback (most recent call last):
|
|
...
|
|
Exception: I meant to do that
|
|
|
|
# This time the object never got saved
|
|
>>> Reporter.objects.all()
|
|
[<Reporter: Alice Smith>, <Reporter: Ben Jones>]
|
|
|
|
# If there aren't any exceptions, the data will get saved
|
|
>>> def remove_a_reporter():
|
|
... r = Reporter.objects.get(first_name="Alice")
|
|
... r.delete()
|
|
...
|
|
>>> remove_comitted_on_success = transaction.commit_on_success(remove_a_reporter)
|
|
>>> remove_comitted_on_success()
|
|
>>> Reporter.objects.all()
|
|
[<Reporter: Ben Jones>]
|
|
|
|
# You can manually manage transactions if you really want to, but you
|
|
# have to remember to commit/rollback
|
|
>>> def manually_managed():
|
|
... r = Reporter(first_name="Carol", last_name="Doe")
|
|
... r.save()
|
|
... transaction.commit()
|
|
>>> manually_managed = transaction.commit_manually(manually_managed)
|
|
>>> manually_managed()
|
|
>>> Reporter.objects.all()
|
|
[<Reporter: Ben Jones>, <Reporter: Carol Doe>]
|
|
|
|
# If you forget, you'll get bad errors
|
|
>>> def manually_managed_mistake():
|
|
... r = Reporter(first_name="David", last_name="Davidson")
|
|
... r.save()
|
|
... # oops, I forgot to commit/rollback!
|
|
>>> manually_managed_mistake = transaction.commit_manually(manually_managed_mistake)
|
|
>>> manually_managed_mistake()
|
|
Traceback (most recent call last):
|
|
...
|
|
TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK
|
|
"""
|