Django-1.2.1/tests/modeltests/transactions/models.py

   1 """
   2 15. Transactions
   3
   4 Django handles transactions in three different ways. The default is to commit
   5 each transaction upon a write, but you can decorate a function to get
   6 commit-on-success behavior. Alternatively, you can manage the transaction
   7 manually.
   8 """
   9
  10 from django.db import models, DEFAULT_DB_ALIAS
  11
  12 class Reporter(models.Model):
  13     first_name = models.CharField(max_length=30)
  14     last_name = models.CharField(max_length=30)
  15     email = models.EmailField()
  16
  17     class Meta:
  18         ordering = ('first_name', 'last_name')
  19
  20     def __unicode__(self):
  21         return u"%s %s" % (self.first_name, self.last_name)
  22
  23 __test__ = {'API_TESTS':"""
  24 >>> from django.db import connection, transaction
  25 """}
  26
  27 from django.conf import settings
  28
  29 building_docs = getattr(settings, 'BUILDING_DOCS', False)
  30
  31 if building_docs or settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] != 'django.db.backends.mysql':
  32     __test__['API_TESTS'] += """
  33 # the default behavior is to autocommit after each save() action
  34 >>> def create_a_reporter_then_fail(first, last):
  35 ...     a = Reporter(first_name=first, last_name=last)
  36 ...     a.save()
  37 ...     raise Exception("I meant to do that")
  38 ...
  39 >>> create_a_reporter_then_fail("Alice", "Smith")
  40 Traceback (most recent call last):
  41     ...
  42 Exception: I meant to do that
  43
  44 # The object created before the exception still exists
  45 >>> Reporter.objects.all()
  46 [<Reporter: Alice Smith>]
  47
  48 # the autocommit decorator works exactly the same as the default behavior
  49 >>> autocomitted_create_then_fail = transaction.autocommit(create_a_reporter_then_fail)
  50 >>> autocomitted_create_then_fail("Ben", "Jones")
  51 Traceback (most recent call last):
  52     ...
  53 Exception: I meant to do that
  54
  55 # Same behavior as before
  56 >>> Reporter.objects.all()
  57 [<Reporter: Alice Smith>, <Reporter: Ben Jones>]
  58
  59 # the autocommit decorator also works with a using argument
  60 >>> using_autocomitted_create_then_fail = transaction.autocommit(using='default')(create_a_reporter_then_fail)
  61 >>> using_autocomitted_create_then_fail("Carol", "Doe")
  62 Traceback (most recent call last):
  63     ...
  64 Exception: I meant to do that
  65
  66 # Same behavior as before
  67 >>> Reporter.objects.all()
  68 [<Reporter: Alice Smith>, <Reporter: Ben Jones>, <Reporter: Carol Doe>]
  69
  70 # With the commit_on_success decorator, the transaction is only committed if the
  71 # function doesn't throw an exception
  72 >>> committed_on_success = transaction.commit_on_success(create_a_reporter_then_fail)
  73 >>> committed_on_success("Dirk", "Gently")
  74 Traceback (most recent call last):
  75     ...
  76 Exception: I meant to do that
  77
  78 # This time the object never got saved
  79 >>> Reporter.objects.all()
  80 [<Reporter: Alice Smith>, <Reporter: Ben Jones>, <Reporter: Carol Doe>]
  81
  82 # commit_on_success decorator also works with a using argument
  83 >>> using_committed_on_success = transaction.commit_on_success(using='default')(create_a_reporter_then_fail)
  84 >>> using_committed_on_success("Dirk", "Gently")
  85 Traceback (most recent call last):
  86     ...
  87 Exception: I meant to do that
  88
  89 # This time the object never got saved
  90 >>> Reporter.objects.all()
  91 [<Reporter: Alice Smith>, <Reporter: Ben Jones>, <Reporter: Carol Doe>]
  92
  93 # If there aren't any exceptions, the data will get saved
  94 >>> def remove_a_reporter():
  95 ...     r = Reporter.objects.get(first_name="Alice")
  96 ...     r.delete()
  97 ...
  98 >>> remove_comitted_on_success = transaction.commit_on_success(remove_a_reporter)
  99 >>> remove_comitted_on_success()
 100 >>> Reporter.objects.all()
 101 [<Reporter: Ben Jones>, <Reporter: Carol Doe>]
 102
 103 # You can manually manage transactions if you really want to, but you
 104 # have to remember to commit/rollback
 105 >>> def manually_managed():
 106 ...     r = Reporter(first_name="Dirk", last_name="Gently")
 107 ...     r.save()
 108 ...     transaction.commit()
 109 >>> manually_managed = transaction.commit_manually(manually_managed)
 110 >>> manually_managed()
 111 >>> Reporter.objects.all()
 112 [<Reporter: Ben Jones>, <Reporter: Carol Doe>, <Reporter: Dirk Gently>]
 113
 114 # If you forget, you'll get bad errors
 115 >>> def manually_managed_mistake():
 116 ...     r = Reporter(first_name="Edward", last_name="Woodward")
 117 ...     r.save()
 118 ...     # oops, I forgot to commit/rollback!
 119 >>> manually_managed_mistake = transaction.commit_manually(manually_managed_mistake)
 120 >>> manually_managed_mistake()
 121 Traceback (most recent call last):
 122     ...
 123 TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK
 124
 125 # commit_manually also works with a using argument
 126 >>> using_manually_managed_mistake = transaction.commit_manually(using='default')(manually_managed_mistake)
 127 >>> using_manually_managed_mistake()
 128 Traceback (most recent call last):
 129     ...
 130 TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK
 131
 132 """
 133
 134 # Regression for #11900: If a function wrapped by commit_on_success writes a
 135 # transaction that can't be committed, that transaction should be rolled back.
 136 # The bug is only visible using the psycopg2 backend, though
 137 # the fix is generally a good idea.
 138 pgsql_backends = ('django.db.backends.postgresql_psycopg2', 'postgresql_psycopg2',)
 139 if building_docs or settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] in pgsql_backends:
 140     __test__['API_TESTS'] += """
 141 >>> def execute_bad_sql():
 142 ...     cursor = connection.cursor()
 143 ...     cursor.execute("INSERT INTO transactions_reporter (first_name, last_name) VALUES ('Douglas', 'Adams');")
 144 ...     transaction.set_dirty()
 145 ...
 146 >>> execute_bad_sql = transaction.commit_on_success(execute_bad_sql)
 147 >>> execute_bad_sql()
 148 Traceback (most recent call last):
 149     ...
 150 IntegrityError: null value in column "email" violates not-null constraint
 151 <BLANKLINE>
 152
 153 >>> transaction.rollback()
 154
 155 """