diff --git a/django/db/models/query.py b/django/db/models/query.py index 2f9f9e24ec..563b902bb5 100644 --- a/django/db/models/query.py +++ b/django/db/models/query.py @@ -651,6 +651,10 @@ class QuerySet(object): 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) @@ -795,6 +799,10 @@ class EmptyQuerySet(QuerySet): # (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): diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py index a9fca7df11..9ce1e7bf2d 100644 --- a/django/db/models/sql/where.py +++ b/django/db/models/sql/where.py @@ -66,6 +66,8 @@ class WhereNode(tree.Node): # 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) diff --git a/tests/regressiontests/queries/models.py b/tests/regressiontests/queries/models.py index a3247bb460..05842ebe7b 100644 --- a/tests/regressiontests/queries/models.py +++ b/tests/regressiontests/queries/models.py @@ -1015,6 +1015,13 @@ performance problems on backends like MySQL. >>> Annotation.objects.filter(notes__in=Note.objects.filter(note="n1")) [] +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__