Ticket #27159: ticket_27159.diff

django/db/models/query.py

@@ -204 +204 @@
         """
         Allows the QuerySet to be pickled.
         """
-        # Force the cache to be fully populated.
-        self._fetch_all()
         obj_dict = self.__dict__.copy()
         obj_dict[DJANGO_VERSION_PICKLE_KEY] = get_version()
         return obj_dict

tests/queryset_pickle/models.py

@@ -60 +60 @@
 
 class M2MModel(models.Model):
     groups = models.ManyToManyField(Group)
+
+
+class Parent(models.Model):
+    name = models.CharField(max_length=64)
+
+
+class Child(models.Model):
+    name = models.CharField(max_length=64)
+    parent = models.ForeignKey(Parent, on_delete=models.CASCADE)
+ No newline at end of file

tests/queryset_pickle/tests.py

@@ -9 +9 @@
 from django.utils import six
 from django.utils.version import get_version
 
-from .models import Container, Event, Group, Happening, M2MModel
+from .models import Container, Event, Group, Happening, M2MModel, Parent, Child
 
 
 class PickleabilityTestCase(TestCase):
@@ -153 +153 @@
         msg = "Pickled queryset instance's Django version 1.0 does not match the current version %s." % get_version()
         with self.assertRaisesMessage(RuntimeWarning, msg):
             pickle.loads(pickle.dumps(qs))
+
+    def test_queryset_evaluation(self):
+        """
+        #27159 -- Test that no unintentional queryset evaluation happens
+        """
+        for i in range(1, 100000):
+            Parent(name='Parent {}'.format(i)).save()
+
+        child = Child(name='Child 1', parent=Parent.objects.all()[0])
+        
+        parents = Parent.objects.all()
+        children = Child.objects.filter(parent__in=parents)
+
+        dumped = pickle.dumps(children.query)
+        # Assume that such a simple query is less than a megabyte pickled
+        self.assertLess(len(dumped), 1024 * 1024)
+ No newline at end of file