Author: mtredinnick
Date: 2009-01-07 23:16:21 -0600 (Wed, 07 Jan 2009)
New Revision: 9715
Modified:
django/trunk/django/db/models/query.py
django/trunk/django/db/models/sql/where.py
django/trunk/tests/regressiontests/queries/models.py
Log:
Using querysets as an rvalue in filter() calls was causing an unnecessary
database query, due to a bool() call. This change stops that behaviour.
Modified: django/trunk/django/db/models/query.py
===================================================================
--- django/trunk/django/db/models/query.py 2009-01-08 05:15:41 UTC (rev
9714)
+++ django/trunk/django/db/models/query.py 2009-01-08 05:16:21 UTC (rev
9715)
@@ -651,6 +651,10 @@
obj = self.values("pk")
return obj.query.as_nested_sql()
+ # When used as part of a nested query, a queryset will never be an "always
+ # empty" result.
+ value_annotation = True
+
class ValuesQuerySet(QuerySet):
def __init__(self, *args, **kwargs):
super(ValuesQuerySet, self).__init__(*args, **kwargs)
@@ -795,7 +799,11 @@
# (it raises StopIteration immediately).
yield iter([]).next()
+ # EmptyQuerySet is always an empty result in where-clauses (and similar
+ # situations).
+ value_annotation = False
+
def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0,
requested=None):
"""
Modified: django/trunk/django/db/models/sql/where.py
===================================================================
--- django/trunk/django/db/models/sql/where.py 2009-01-08 05:15:41 UTC (rev
9714)
+++ django/trunk/django/db/models/sql/where.py 2009-01-08 05:16:21 UTC (rev
9715)
@@ -66,6 +66,8 @@
# here in the future (using Python types is suggested for consistency).
if isinstance(value, datetime.datetime):
annotation = datetime.datetime
+ elif hasattr(value, 'value_annotation'):
+ annotation = value.value_annotation
else:
annotation = bool(value)
Modified: django/trunk/tests/regressiontests/queries/models.py
===================================================================
--- django/trunk/tests/regressiontests/queries/models.py 2009-01-08
05:15:41 UTC (rev 9714)
+++ django/trunk/tests/regressiontests/queries/models.py 2009-01-08
05:16:21 UTC (rev 9715)
@@ -1015,6 +1015,13 @@
>>> Annotation.objects.filter(notes__in=Note.objects.filter(note="n1"))
[<Annotation: a1>]
+Nested queries should not evaluate the inner query as part of constructing the
+SQL. This test verifies this: if the inner query is evaluated, the outer "in"
+lookup will raise an EmptyResultSet exception (as the inner query returns
+nothing).
+>>> print
Annotation.objects.filter(notes__in=Note.objects.filter(note="xyzzy")).query
+SELECT ...
+
"""}
# In Python 2.3 and the Python 2.6 beta releases, exceptions raised in __len__
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