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Fixed #2473 -- Added special case for '__in=[]' (empty set) queries, …

…because 'WHERE attr IN ()' is invalid SQL on many backends. Thanks, Gary Wilson.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4283 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit ddb9b7d57a1da6b8715a62376cbb8605e6b2351b 1 parent 295f4c9
@freakboy3742 freakboy3742 authored
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10 django/db/models/query.py
@@ -641,7 +641,15 @@ def get_where_clause(lookup_type, table_prefix, field_name, value):
except KeyError:
pass
if lookup_type == 'in':
- return '%s%s IN (%s)' % (table_prefix, field_name, ','.join(['%s' for v in value]))
+ in_string = ','.join(['%s' for id in value])
+ if in_string:
+ return '%s%s IN (%s)' % (table_prefix, field_name, in_string)
+ else:
+ # Most backends do not accept an empty string inside the IN
+ # expression, i.e. cannot do "WHERE ... IN ()". Since there are
+ # also some backends that do not accept "WHERE false", we instead
+ # use an expression that always evaluates to False.
+ return '0=1'
elif lookup_type == 'range':
return '%s%s BETWEEN %%s AND %%s' % (table_prefix, field_name)
elif lookup_type in ('year', 'month', 'day'):
View
15 tests/modeltests/or_lookups/models.py
@@ -69,6 +69,21 @@ def __str__(self):
>>> Article.objects.filter(Q(pk=1) | Q(pk=2) | Q(pk=3))
[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
+# You could also use "in" to accomplish the same as above.
+>>> Article.objects.filter(pk__in=[1,2,3])
+[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
+
+>>> Article.objects.filter(pk__in=[1,2,3,4])
+[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
+
+# Passing "in" an empty list returns no results ...
+>>> Article.objects.filter(pk__in=[])
+[]
+
+# ... but can return results if we OR it with another query.
+>>> Article.objects.filter(Q(pk__in=[]) | Q(headline__icontains='goodbye'))
+[<Article: Goodbye>, <Article: Hello and goodbye>]
+
# Q arg objects are ANDed
>>> Article.objects.filter(Q(headline__startswith='Hello'), Q(headline__contains='bye'))
[<Article: Hello and goodbye>]
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