#29684: PostgreSQL causes "TypeError: unhashable type: 'list'" when using
aggregate
function
-------------------------------------+-------------------------------------
Reporter: ptrstn | Owner: nobody
Type: Bug | Status: new
Component: | Version: 2.0
Uncategorized | Keywords: PostgreSQL,
Severity: Normal | aggregate, Count, tuple, array,
Triage Stage: | annotate, unhashable type, list
Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
I get following error message:
{{{
self = <When: WHEN <Q: (AND: ('attribute_a__in', [1]))> THEN Value(yes)>
def __hash__(self):
path, args, kwargs = self.deconstruct()
h = hash(path) ^ hash(args)
for kwarg in kwargs.items():
> h ^= hash(kwarg)
E TypeError: unhashable type: 'list'
venv\lib\site-packages\django\db\models\expressions.py:386: TypeError
}}}
running this test code:
{{{
def test_mymodel(self):
my_models = MyModel.objects \
.annotate(my_annotation=Case(
When(attribute_a__in=[1, 2], then=Value('yes')),
default=Value('no'),
output_field=CharField())
) \
.annotate(count_a=Count("my_annotation"))
print(my_models)
}}}
For this model:
{{{
class MyModel(models.Model):
attribute_a = models.IntegerField()
}}}
The complete test code can be checked at https://github.com/random-code-
chunks/django_postgres_aggregate_problem
As you can see in travis-ci, this bug only appears in version 2.0 of
django and is fixed in 2.1 and 1.11 (https://travis-ci.com/random-code-
chunks/django_postgres_aggregate_problem)
This error does not appear when using SQLite.
The above test case can be fixed using a tuple instead of a list
{{{
When(attribute_a__in=(1, 2), then=Value('yes')),
}}}
Somehow related:
https://code.djangoproject.com/ticket/28762
https://code.djangoproject.com/ticket/29139
--
Ticket URL: <https://code.djangoproject.com/ticket/29684>
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