[Django] #20250: AttributeError when filtering annotated queryset with negated Q (via fk)

[Django]

#20250: AttributeError when filtering annotated queryset with negated Q (via fk)
----------------------------------------------+----------------------------
     Reporter:  jan.koutny@…                  |      Owner:  nobody
         Type:  Bug                           |     Status:  new
    Component:  Database layer (models, ORM)  |    Version:  1.4
     Severity:  Normal                        |   Keywords:  annotate
 Triage Stage:  Unreviewed                    |  AttributeError
Easy pickings:  0                             |  Has patch:  0
                                              |      UI/UX:  0
----------------------------------------------+----------------------------
 If these conditions are met:
 * annotated queryset
 * Q is filtering attribute related via foreign key
 * Q is negation

 Then {{{AttributeError: 'NoneType' object has no attribute 'startswith'}}}
 exception is throwed. Stack looks the same as in 12687 (fixed), see below.

 Note that *all* conditions above are necessary, code works if one omitted.
 Reproducible with Django 1.4.5, python 2.6.8.

 {{{
 Traceback (most recent call last):
   File "bug.py", line 16, in <module>
     print qst.query
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/query.py",
 line 167, in __str__
     sql, params = self.sql_with_params()
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/query.py",
 line 175, in sql_with_params
     return self.get_compiler(DEFAULT_DB_ALIAS).as_sql()
   File "/usr/lib/python2.6/site-
 packages/django/db/models/sql/compiler.py", line 82, in as_sql
     where, w_params = self.query.where.as_sql(qn=qn,
 connection=self.connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 91, in as_sql
     sql, params = child.as_sql(qn=qn, connection=connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 91, in as_sql
     sql, params = child.as_sql(qn=qn, connection=connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 91, in as_sql
     sql, params = child.as_sql(qn=qn, connection=connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 91, in as_sql
     sql, params = child.as_sql(qn=qn, connection=connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 91, in as_sql
     sql, params = child.as_sql(qn=qn, connection=connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 94, in as_sql
     sql, params = self.make_atom(child, qn, connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 154, in make_atom
     field_sql = self.sql_for_columns(lvalue, qn, connection)
   File "/usr/lib/python2.6/site-packages/django/db/models/sql/where.py",
 line 227, in sql_for_columns
     lhs = '%s.%s' % (qn(table_alias), qn(name))
   File "/usr/lib/python2.6/site-
 packages/django/db/models/sql/compiler.py", line 49, in
 quote_name_unless_alias
     r = self.connection.ops.quote_name(name)
   File "/usr/lib/python2.6/site-
 packages/django/db/backends/sqlite3/base.py", line 145, in quote_name
     if name.startswith('"') and name.endswith('"'):
 AttributeError: 'NoneType' object has no attribute 'startswith'
 }}}


 Code snippet to reproduce the issue, bug.py:
 {{{
 from bug.models import *
 from django.db.models import Q,Count

 qobj=~Q(rtom3__x=0) #TOXIC
 #qobj=~Q(x=0) #OK
 #qobj=Q(rtom3__x=0) #OK

 qst =  M1.objects.annotate(Count('m2')) #TOXIC
 #qst =  M1.objects.all() #OK

 qst = qst.filter(qobj)

 #Gracefully returns [], no attempt to hit the database!!!!
 #print qst

 #Throws an exception!
 print qst.query
 }}}

 and models.py:
 {{{
 from django.db import models

 class M1(models.Model):
         rtom3 = models.ForeignKey("M3")
         x = models.IntegerField()

 class M2(models.Model):
         rtom1 = models.ForeignKey("M1")

 class M3(models.Model):
         x = models.IntegerField()
 }}}

-- 
Ticket URL: <https://code.djangoproject.com/ticket/20250>
Django <https://code.djangoproject.com/>
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