From ffe755e990fa7e680960c7a413d387a79f194204 Mon Sep 17 00:00:00 2001
From: Tim Graham <timograham@gmail.com>
Date: Wed, 5 Aug 2015 15:52:11 -0400
Subject: [PATCH] [1.8.x] Fixed #24951 -- Fixed AssertionError in delete
 queries involving a foreign/primary key.
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Thanks Anssi Kääriäinen for help.

Backport of 333cbdcd2de4546e33ad50ebd8b67e1a1e87aeec from master
---
 django/db/models/sql/compiler.py | 2 +-
 docs/releases/1.8.5.txt          | 3 ++-
 tests/one_to_one/models.py       | 2 +-
 tests/one_to_one/tests.py        | 8 +++++++-
 4 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 688e3f741e4..fed4353a3a5 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -986,7 +986,7 @@ class SQLDeleteCompiler(SQLCompiler):
         Creates the SQL for this query. Returns the SQL string and list of
         parameters.
         """
-        assert len(self.query.tables) == 1, \
+        assert len([t for t in self.query.tables if self.query.alias_refcount[t] > 0]) == 1, \
             "Can only delete from one table at a time."
         qn = self.quote_name_unless_alias
         result = ['DELETE FROM %s' % qn(self.query.tables[0])]
diff --git a/docs/releases/1.8.5.txt b/docs/releases/1.8.5.txt
index 43a959197bc..df7783f4dfe 100644
--- a/docs/releases/1.8.5.txt
+++ b/docs/releases/1.8.5.txt
@@ -9,4 +9,5 @@ Django 1.8.5 fixes several bugs in 1.8.4.
 Bugfixes
 ========
 
-* ...
+* Fixed ``AssertionError`` in some delete queries with a model containing a
+  field that is both a foreign and primary key (:ticket:`24951`).
diff --git a/tests/one_to_one/models.py b/tests/one_to_one/models.py
index 8a5defe856d..a71e65a0f93 100644
--- a/tests/one_to_one/models.py
+++ b/tests/one_to_one/models.py
@@ -83,7 +83,7 @@ class MultiModel(models.Model):
 
 
 class Target(models.Model):
-    pass
+    name = models.CharField(max_length=50)
 
 
 class Pointer(models.Model):
diff --git a/tests/one_to_one/tests.py b/tests/one_to_one/tests.py
index 94a6ad957ea..b71ee0645af 100644
--- a/tests/one_to_one/tests.py
+++ b/tests/one_to_one/tests.py
@@ -5,7 +5,8 @@ from django.test import TestCase
 
 from .models import (
     Bar, Director, Favorites, HiddenPointer, ManualPrimaryKey, MultiModel,
-    Place, RelatedModel, Restaurant, School, Target, UndergroundBar, Waiter,
+    Place, Pointer, RelatedModel, Restaurant, School, Target, UndergroundBar,
+    Waiter,
 )
 
 
@@ -256,6 +257,11 @@ class OneToOneTests(TestCase):
             []
         )
 
+    def test_o2o_primary_key_delete(self):
+        t = Target.objects.create(name='name')
+        Pointer.objects.create(other=t)
+        Pointer.objects.filter(other__name='name').delete()
+
     def test_reverse_object_does_not_exist_cache(self):
         """
         Regression for #13839 and #17439.