#2473: [patch] 'in' QuerySet operator generates invalid SQL for empty list
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Reporter: [EMAIL PROTECTED] | Owner: adrian
Type: defect | Status: new
Priority: normal | Milestone:
Component: Database wrapper | Version:
Severity: normal | Keywords:
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If an empty iterable is passed to the 'in' operator in a QuerySet method
or Q() call, the SQL generated is invalid: 'WHERE ... IN ()'; this
results in a ProgrammingError exception:
For example:
{{{
>>> Book.objects.filter(id__in=[])
Traceback (most recent call last):
File "<console>", line 1, in ?
File "/usr/lib/python2.4/site-packages/django/db/models/query.py", line
97, in __repr__
return repr(self._get_data())
File "/usr/lib/python2.4/site-packages/django/db/models/query.py", line
430, in _get_data
self._result_cache = list(self.iterator())
File "/usr/lib/python2.4/site-packages/django/db/models/query.py", line
172, in iterator
cursor.execute("SELECT " + (self._distinct and "DISTINCT " or "") +
",".join(select) + sql, params)
File "/usr/lib/python2.4/site-packages/django/db/backends/util.py", line
12, in execute
return self.cursor.execute(sql, params)
File "/usr/lib/python2.4/site-
packages/django/db/backends/mysql/base.py", line 35, in execute
return self.cursor.execute(sql, params)
File "/usr/lib/python2.4/site-packages/MySQLdb/cursors.py", line 163, in
execute
self.errorhandler(self, exc, value)
File "/usr/lib/python2.4/site-packages/MySQLdb/connections.py", line 35,
in defaulterrorhandler
raise errorclass, errorvalue
ProgrammingError: (1064, "You have an error in your SQL syntax; check the
manual that corresponds to your MySQL server version for the right syntax
to use near '))' at line 1")
}}}
The SQL generated in this case was:
{{{
SELECT `test_book`.`id`,`test_book`.`title`,`test_book`.`author_id` FROM
`test_book` WHERE (`test_book`.`id` IN ())
}}}
The attached patch will return '0' instead of '... IN ()' if
list(iterable) is empty; i.e. for SQL like this:
{{{
SELECT `test_book`.`id`,`test_book`.`title`,`test_book`.`author_id` FROM
`test_book` WHERE (0)
}}}
--
Ticket URL: <http://code.djangoproject.com/ticket/2473>
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