#34827: select_for_update example raises TransactionManagementError
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Reporter: SydneyUni-Jim | Owner: nobody
Type: Bug | Status: new
Component: Documentation | Version: 4.2
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Description changed by SydneyUni-Jim:
Old description:
> The example for `select_for_update` at
> https://docs.djangoproject.com/en/4.2/ref/models/querysets/#select-for-
> update shows `select-for-update` being used before starting the
> transaction. With Django 4.2.5, this raises a TransactionManagementError.
>
> {{{
> Traceback (most recent call last):
> File "/site-packages/django/db/models/query.py", line 633, in get
> num = len(clone)
> File "/site-packages/django/db/models/query.py", line 380, in __len__
> self._fetch_all()
> File "/site-packages/django/db/models/query.py", line 1881, in
> _fetch_all
> self._result_cache = list(self._iterable_class(self))
> File "/site-packages/django/db/models/query.py", line 91, in __iter__
> results = compiler.execute_sql(
> File "/site-packages/django/db/models/sql/compiler.py", line 1549, in
> execute_sql
> sql, params = self.as_sql()
> File "/site-packages/django/db/models/sql/compiler.py", line 816, in
> as_sql
> raise TransactionManagementError(
> django.db.transaction.TransactionManagementError: select_for_update
> cannot be used outside of a transaction.
> }}}
>
> I think the sample should be:
>
> {{{
> #!python
> from django.db import transaction
>
> with transaction.atomic():
> entries =
> Entry.objects.select_for_update().filter(author=request.user)
> for entry in entries:
> ...
> }}}
New description:
The example for `select_for_update` at
https://docs.djangoproject.com/en/4.2/ref/models/querysets/#select-for-
update shows `select_for_update` being used before starting the
transaction. With Django 4.2.5, this raises a TransactionManagementError.
{{{
Traceback (most recent call last):
File "/site-packages/django/db/models/query.py", line 633, in get
num = len(clone)
File "/site-packages/django/db/models/query.py", line 380, in __len__
self._fetch_all()
File "/site-packages/django/db/models/query.py", line 1881, in
_fetch_all
self._result_cache = list(self._iterable_class(self))
File "/site-packages/django/db/models/query.py", line 91, in __iter__
results = compiler.execute_sql(
File "/site-packages/django/db/models/sql/compiler.py", line 1549, in
execute_sql
sql, params = self.as_sql()
File "/site-packages/django/db/models/sql/compiler.py", line 816, in
as_sql
raise TransactionManagementError(
django.db.transaction.TransactionManagementError: select_for_update cannot
be used outside of a transaction.
}}}
I think the example should be:
{{{
#!python
from django.db import transaction
with transaction.atomic():
entries =
Entry.objects.select_for_update().filter(author=request.user)
for entry in entries:
...
}}}
--
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Ticket URL: <https://code.djangoproject.com/ticket/34827#comment:1>
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