#24148: test_combined_expression test failure on Windows/Python 2
-------------------------------------+-------------------------------------
Reporter: timgraham | Owner: michalmo
Type: Bug | Status: assigned
Component: Database layer | Version: master
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by michalmo):
I've had a look and it's not pretty. The SQL generated in pythons 2.7,
3.2, 3.3 and 3.4 on windows is exactly the same.
sqlite3.version is 2.6.0 on all of them.
What differs is sqlite3.sqlite_version:
py2.7: 3.6.21
py3.2: 3.7.4
py3.3: 3.7.12
py3.4: 3.8.3.1
I installed pysqlite from http://www.lfd.uci.edu/~gohlke/pythonlibs/
(2.6.3 / 3.8.5) and the test passes.
What is happening? SQLite is adding the value in the lookup to the value
in the then.
You can see this better with a different example (with the same test data
as the testcase):
{{{
>>> qs = CaseTestModel.objects.annotate(
... test=Case(
... When(integer=1, then=Value(1)),
... When(integer=2, then=Value(1)),
... When(integer=3, then=Value(1)),
... When(integer=4, then=Value(10)),
... default=Value(1),
... output_field=models.IntegerField(),
... ) + 100,
... ).order_by('pk')
>>> # expected: [(1, 101), (2, 101), (3, 101), (2, 101), (3, 101), (3,
101), (4, 110)]
>>> [(o.integer, o.test) for o in qs]
[(1, 2), (2, 3), (3, 4), (2, 3), (3, 4), (3, 4), (4, 14)]
}}}
Removing the default fixes it (since all the cases are taken care of)
{{{
>>> qs = CaseTestModel.objects.annotate(
... test=Case(
... When(integer=1, then=Value(1)),
... When(integer=2, then=Value(1)),
... When(integer=3, then=Value(1)),
... When(integer=4, then=Value(10)),
... # default=Value(1),
... output_field=models.IntegerField(),
... ) + 100,
... ).order_by('pk')
>>> # expected: [(1, 101), (2, 101), (3, 101), (2, 101), (3, 101), (3,
101), (4, 110)]
>>> [(o.integer, o.test) for o in qs]
[(1, 101), (2, 101), (3, 101), (2, 101), (3, 101), (3, 101), (4, 110)]
}}}
Also, if I send the query as a string without the placeholders it works.
So I assume that SQLite 3.6.21 is mixing up the query parameters. Not sure
if the error is specific to this version, but it seems there was a query
related bug fix in 3.6.22
(http://www.sqlite.org/changes.html#version_3_6_22 ).
Unfortunately, I checked all the windows python versions from 2.7a1 to
2.7.9 and they all have the same sqlite3.sqlite_version, so there's
nothing we can do here other than mark the test as an expected failure and
recommend pysqlite on windows.
--
Ticket URL: <https://code.djangoproject.com/ticket/24148#comment:3>
Django <https://code.djangoproject.com/>
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