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Viewing changes to tests/modeltests/transactions/models.py

  • Committer: adrian
  • Date: 2006-05-02 01:31:56 UTC
  • Revision ID: vcs-imports@canonical.com-20060502013156-2941fcd40d080649
MERGED MAGIC-REMOVAL BRANCH TO TRUNK. This change is highly backwards-incompatible. Please read http://code.djangoproject.com/wiki/RemovingTheMagic for upgrade instructions.

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tests/modeltests/transactions/models.py
 
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"""
 
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XXX. Transactions
 
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Django handles transactions in three different ways. The default is to commit
 
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each transaction upon a write, but you can decorate a function to get
 
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commit-on-success behavior. Alternatively, you can manage the transaction
 
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manually.
 
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"""
 
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from django.db import models
 
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class Reporter(models.Model):
 
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    first_name = models.CharField(maxlength=30)
 
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    last_name = models.CharField(maxlength=30)
 
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    email = models.EmailField()
 
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    def __repr__(self):
 
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        return "%s %s" % (self.first_name, self.last_name)
 
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API_TESTS = """
 
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>>> from django.db import connection, transaction
 
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# the default behavior is to autocommit after each save() action
 
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>>> def create_a_reporter_then_fail(first, last):
 
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...     a = Reporter(first_name=first, last_name=last)
 
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...     a.save()
 
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...     raise Exception("I meant to do that")
 
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...
 
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>>> create_a_reporter_then_fail("Alice", "Smith")
 
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Traceback (most recent call last):
 
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    ...
 
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Exception: I meant to do that
 
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# The object created before the exception still exists
 
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>>> Reporter.objects.all()
 
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[Alice Smith]
 
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# the autocommit decorator works exactly the same as the default behavior
 
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>>> autocomitted_create_then_fail = transaction.autocommit(create_a_reporter_then_fail)
 
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>>> autocomitted_create_then_fail("Ben", "Jones")
 
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Traceback (most recent call last):
 
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    ...
 
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Exception: I meant to do that
 
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# Same behavior as before
 
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>>> Reporter.objects.all()
 
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[Alice Smith, Ben Jones]
 
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# With the commit_on_success decorator, the transaction is only comitted if the
 
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# function doesn't throw an exception
 
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>>> committed_on_success = transaction.commit_on_success(create_a_reporter_then_fail)
 
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>>> committed_on_success("Carol", "Doe")
 
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Traceback (most recent call last):
 
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    ...
 
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Exception: I meant to do that
 
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# This time the object never got saved
 
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>>> Reporter.objects.all()
 
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[Alice Smith, Ben Jones]
 
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# If there aren't any exceptions, the data will get saved
 
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>>> def remove_a_reporter():
 
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...     r = Reporter.objects.get(first_name="Alice")
 
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...     r.delete()
 
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...
 
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>>> remove_comitted_on_success = transaction.commit_on_success(remove_a_reporter)
 
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>>> remove_comitted_on_success()
 
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>>> Reporter.objects.all()
 
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[Ben Jones]
 
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# You can manually manage transactions if you really want to, but you
 
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# have to remember to commit/rollback
 
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>>> def manually_managed():
 
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...     r = Reporter(first_name="Carol", last_name="Doe")
 
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...     r.save()
 
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...     transaction.commit()
 
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>>> manually_managed = transaction.commit_manually(manually_managed)
 
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>>> manually_managed()
 
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>>> Reporter.objects.all()
 
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[Ben Jones, Carol Doe]
 
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# If you forget, you'll get bad errors
 
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>>> def manually_managed_mistake():
 
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...     r = Reporter(first_name="David", last_name="Davidson")
 
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...     r.save()
 
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...     # oops, I forgot to commit/rollback!
 
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>>> manually_managed_mistake = transaction.commit_manually(manually_managed_mistake)
 
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>>> manually_managed_mistake()
 
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Traceback (most recent call last):
 
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    ...
 
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TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK
 
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"""
 
 
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