#28863: Regression in 2.0: an annotated then filtered db function using a Q
object
crashes
-------------------------------------+-------------------------------------
Reporter: Adam | Owner: nobody
(Chainz) Johnson |
Type: Bug | Status: new
Component: Database | Version: 2.0
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
I noticed this when trying to test Django-MySQL against 2.0 in
https://github.com/adamchainz/django-mysql/pull/403 . Basically there's a
function called If() that takes a Q object, and it's tested in a variety
of scenarios. Only one of those scenarios was crashing with Django 2.0b1
and rc1.
I found a minimal test to reproduce it in the django test suite:
{{{
diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index ca331aeb03..d31935ddb4 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -73,6 +73,12 @@ class BasicExpressionsTests(TestCase):
],
)
+ def test_filtering_on_annoate_that_uses_q(self):
+ qs = Company.objects.annotate(
+ name_check_len=Length(Q(name__gt='T'))
+ ).filter(name_check_len__gt=1)
+ list(qs)
+
def test_filter_inter_attribute(self):
# We can filter on attribute relationships on same model obj,
e.g.
# find companies where the number of employees is greater
}}}
It fails with this stacktrace:
{{{
ERROR: test_filtering_on_annoate_that_uses_q
(expressions.tests.BasicExpressionsTests)
----------------------------------------------------------------------
Traceback (most recent call last):
File
"/Users/chainz/Documents/Projects/django/tests/expressions/tests.py", line
80, in test_filtering_on_annoate_that_uses_q
list(qs)
File
"/Users/chainz/Documents/Projects/django/django/db/models/query.py", line
272, in __iter__
self._fetch_all()
File
"/Users/chainz/Documents/Projects/django/django/db/models/query.py", line
1179, in _fetch_all
self._result_cache = list(self._iterable_class(self))
File
"/Users/chainz/Documents/Projects/django/django/db/models/query.py", line
54, in __iter__
results = compiler.execute_sql(chunked_fetch=self.chunked_fetch,
chunk_size=self.chunk_size)
File
"/Users/chainz/Documents/Projects/django/django/db/models/sql/compiler.py",
line 1050, in execute_sql
sql, params = self.as_sql()
File
"/Users/chainz/Documents/Projects/django/django/db/models/sql/compiler.py",
line 458, in as_sql
where, w_params = self.compile(self.where) if self.where is not None
else ("", [])
File
"/Users/chainz/Documents/Projects/django/django/db/models/sql/compiler.py",
line 390, in compile
sql, params = node.as_sql(self, self.connection)
File
"/Users/chainz/Documents/Projects/django/django/db/models/sql/where.py",
line 79, in as_sql
sql, params = compiler.compile(child)
File
"/Users/chainz/Documents/Projects/django/django/db/models/sql/compiler.py",
line 390, in compile
sql, params = node.as_sql(self, self.connection)
File
"/Users/chainz/Documents/Projects/django/django/db/models/lookups.py",
line 160, in as_sql
lhs_sql, params = self.process_lhs(compiler, connection)
File
"/Users/chainz/Documents/Projects/django/django/db/models/lookups.py",
line 151, in process_lhs
lhs_sql, params = super().process_lhs(compiler, connection, lhs)
File
"/Users/chainz/Documents/Projects/django/django/db/models/lookups.py",
line 77, in process_lhs
lhs = lhs.resolve_expression(compiler.query)
File
"/Users/chainz/Documents/Projects/django/django/db/models/expressions.py",
line 597, in resolve_expression
c.source_expressions[pos] = arg.resolve_expression(query, allow_joins,
reuse, summarize, for_save)
AttributeError: 'WhereNode' object has no attribute 'resolve_expression'
}}}
I then used git bisect with this test and found it bisected to:
{{{
commit bde86ce9ae17ee52aa5be9b74b64422f5219530d
Author: Sergey Fedoseev <[email protected]>
Date: Sat Apr 1 18:47:49 2017 +0500
Fixed #25605 -- Made GIS DB functions accept geometric expressions,
not only values, in all positions.
}}}
This change was the culprit, if you revert only this conditional, the test
passes:
{{{
diff --git a/django/db/models/lookups.py b/django/db/models/lookups.py
index d96c4468f5..c37fcabba4 100644
--- a/django/db/models/lookups.py
+++ b/django/db/models/lookups.py
@@ -76,6 +76,8 @@ class Lookup:
def process_lhs(self, compiler, connection, lhs=None):
lhs = lhs or self.lhs
+ if hasattr(lhs, 'resolve_expression'):
+ lhs = lhs.resolve_expression(compiler.query)
return compiler.compile(lhs)
def process_rhs(self, compiler, connection):
}}}
I'm not sure of the fix, maybe `WhereNode` should be given a
`resolve_expression` method? Or should the change in `Lookup`'s
`process_lhs` be more considered?
--
Ticket URL: <https://code.djangoproject.com/ticket/28863>
Django <https://code.djangoproject.com/>
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