diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py index 662d99a4a2..277ccef4f2 100644 --- a/django/db/models/sql/where.py +++ b/django/db/models/sql/where.py @@ -43,6 +43,10 @@ class WhereNode(tree.Node): return alias, col, field, lookup_type, value = data + if hasattr(value, '__iter__') and hasattr(value, 'next'): + # Consume any generators immediately, so that we can determine + # emptiness and transform any non-empty values correctly. + value = list(value) try: if field: params = field.get_db_prep_lookup(lookup_type, value) diff --git a/tests/regressiontests/queries/models.py b/tests/regressiontests/queries/models.py index d2abd21df8..c95171d0b1 100644 --- a/tests/regressiontests/queries/models.py +++ b/tests/regressiontests/queries/models.py @@ -1068,6 +1068,19 @@ to set things up correctly internally so that subqueries can continue properly. >>> Tag.objects.filter(name__in=()).update(name="foo") 0 +Bug #10432 (see also the Python 2.4+ tests for this, below). Testing an empty +"__in" filter with a generator as the value. +>>> def f(): +... return iter([]) +>>> n_obj = Note.objects.all()[0] +>>> def g(): +... for i in [n_obj.pk]: +... yield i +>>> Note.objects.filter(pk__in=f()) +[] +>>> list(Note.objects.filter(pk__in=g())) == [n_obj] +True + """} # In Python 2.3 and the Python 2.6 beta releases, exceptions raised in __len__ @@ -1101,3 +1114,14 @@ FieldError: Infinite loop caused by ordering. [] """ + +# Generator expressions are only in Python 2.4 and later. +if sys.version_info >= (2, 4): + __test__["API_TESTS"] += """ +Using an empty generator expression as the rvalue for an "__in" lookup is legal +(regression for #10432). +>>> Note.objects.filter(pk__in=(x for x in ())) +[] + +""" +