On Thursday 25 Mar 2010 9:17:12 pm Malcolm Tredinnick wrote:
> I don't understand what you are saying here. If the instance exists (as
> in, the filter parameters passed to get would return a single item),
> that instance is returned and the default parameters are never
> considered. So the values you pass for slno and mode are irrelevant. If
> the equivalent get() call would not return anything, then the instance
> does not exist and it's clear that the default parameter must contain
> correct data that can be used to create a new object -- including not
> violating any unique constraints. Perhaps you could show the code call
> you are making, rather than writing it out as a sentence.
>
> In short: get_or_create() first runs the get(). If that returns
> something, it is what is returned. If the get() fails with no object
> being present, then the instance DOES NOT exist and a new one is
> created, with all the same requirements as if you'd created a new object
> from scratch (e.g. no unique constraint violations).
>
sorry for not replying to this - for some reason all your recent mails have
gone to the spam folder! I only became aware of this mail when I saw a reply
to it. Here is what I mean - A simple model with two fields, 'name' is unique,
and 'num' is not null:
>>> Tm.objects.get_or_create(name='me',num=1)
>>>
(<Tm: me>, True)
>>> Tm.objects.get_or_create(name='me',num=2)
>>>
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/lib/python2.6/django/db/models/manager.py", line 135, in
get_or_create
return self.get_query_set().get_or_create(**kwargs)
File "/usr/lib/python2.6/django/db/models/query.py", line 375, in
get_or_create
transaction.savepoint_rollback(sid, using=self.db)
File "/usr/lib/python2.6/django/db/transaction.py", line 242, in
savepoint_rollback
connection._savepoint_rollback(sid)
File "/usr/lib/python2.6/django/db/backends/__init__.py", line 61, in
_savepoint_rollback
self.cursor().execute(self.ops.savepoint_rollback_sql(sid))
File "/usr/lib/python2.6/django/db/backends/__init__.py", line 75, in cursor
cursor = self._cursor()
File "/usr/lib/python2.6/django/db/backends/postgresql/base.py", line 149,
in _cursor
cursor.execute("SET client_encoding to 'UNICODE'")
ProgrammingError: ERROR: current transaction is aborted, commands ignored
until end of transaction block
SET client_encoding to 'UNICODE'
--
regards
Kenneth Gonsalves
Senior Associate
NRC-FOSS
http://certificate.nrcfoss.au-kbc.org.in
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