Added a db_constraint option to ForeignKeys.

This controls whether or not a database level cosntraint is created. This is useful in a few specialized circumstances, but in general should not be used!

2 files changed, 35 insertions, 4 deletions

diff --git a/tests/regressiontests/backends/models.py b/tests/regressiontests/backends/models.py
index a92aa71e17..5876cbe52d 100644
--- a/tests/regressiontests/backends/models.py
+++ b/tests/regressiontests/backends/models.py
@@ -39,7 +39,7 @@ if connection.features.supports_long_model_names:
             verbose_name = 'model_with_long_table_name'
         primary_key_is_quite_long_zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz = models.AutoField(primary_key=True)
         charfield_is_quite_long_zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz = models.CharField(max_length=100)
-        m2m_also_quite_long_zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz = models.ManyToManyField(Person,blank=True)
+        m2m_also_quite_long_zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz = models.ManyToManyField(Person, blank=True)
 
 
 class Tag(models.Model):
@@ -86,3 +86,16 @@ class Item(models.Model):
 
     def __str__(self):
         return self.name
+
+
+@python_2_unicode_compatible
+class Object(models.Model):
+    pass
+
+
+@python_2_unicode_compatible
+class ObjectReference(models.Model):
+    obj = models.ForeignKey(Object, db_constraint=False)
+
+    def __str__(self):
+        return str(self.obj_id)
diff --git a/tests/regressiontests/backends/tests.py b/tests/regressiontests/backends/tests.py
index ed6f07691a..0e1700b36e 100644
--- a/tests/regressiontests/backends/tests.py
+++ b/tests/regressiontests/backends/tests.py
@@ -7,13 +7,12 @@ import threading
 
 from django.conf import settings
 from django.core.management.color import no_style
-from django.core.exceptions import ImproperlyConfigured
 from django.db import (backend, connection, connections, DEFAULT_DB_ALIAS,
     IntegrityError, transaction)
 from django.db.backends.signals import connection_created
 from django.db.backends.postgresql_psycopg2 import version as pg_version
-from django.db.models import fields, Sum, Avg, Variance, StdDev
-from django.db.utils import ConnectionHandler, DatabaseError, load_backend
+from django.db.models import Sum, Avg, Variance, StdDev
+from django.db.utils import ConnectionHandler, DatabaseError
 from django.test import (TestCase, skipUnlessDBFeature, skipIfDBFeature,
     TransactionTestCase)
 from django.test.utils import override_settings, str_prefix
@@ -724,3 +723,22 @@ class MySQLPKZeroTests(TestCase):
     def test_zero_as_autoval(self):
         with self.assertRaises(ValueError):
             models.Square.objects.create(id=0, root=0, square=1)
+
+
+class DBConstraintTestCase(TransactionTestCase):
+    def test_can_reference_existant(self):
+        obj = models.Object.objects.create()
+        ref = models.ObjectReference.objects.create(obj=obj)
+        self.assertEqual(ref.obj, obj)
+
+        ref = models.ObjectReference.objects.get(obj=obj)
+        self.assertEqual(ref.obj, obj)
+
+    def test_can_reference_non_existant(self):
+        self.assertFalse(models.Object.objects.filter(id=12345).exists())
+        ref = models.ObjectReference.objects.create(obj_id=12345)
+        ref_new = models.ObjectReference.objects.get(obj_id=12345)
+        self.assertEqual(ref, ref_new)
+
+        with self.assertRaises(models.Object.DoesNotExist):
+            ref.obj