Merged regressiontests and modeltests into the test root.

tests/defer/tests.py

@@ -0,0 +1,185 @@
+from __future__ import absolute_import
+
+from django.db.models.query_utils import DeferredAttribute, InvalidQuery
+from django.test import TestCase
+
+from .models import Secondary, Primary, Child, BigChild, ChildProxy
+
+
+class DeferTests(TestCase):
+    def assert_delayed(self, obj, num):
+        count = 0
+        for field in obj._meta.fields:
+            if isinstance(obj.__class__.__dict__.get(field.attname),
+                DeferredAttribute):
+                count += 1
+        self.assertEqual(count, num)
+
+    def test_defer(self):
+        # To all outward appearances, instances with deferred fields look the
+        # same as normal instances when we examine attribute values. Therefore
+        # we test for the number of deferred fields on returned instances (by
+        # poking at the internals), as a way to observe what is going on.
+
+        s1 = Secondary.objects.create(first="x1", second="y1")
+        p1 = Primary.objects.create(name="p1", value="xx", related=s1)
+
+        qs = Primary.objects.all()
+
+        self.assert_delayed(qs.defer("name")[0], 1)
+        self.assert_delayed(qs.only("name")[0], 2)
+        self.assert_delayed(qs.defer("related__first")[0], 0)
+
+        # Using 'pk' with only() should result in 3 deferred fields, namely all
+        # of them except the model's primary key see #15494
+        self.assert_delayed(qs.only("pk")[0], 3)
+
+        obj = qs.select_related().only("related__first")[0]
+        self.assert_delayed(obj, 2)
+
+        self.assertEqual(obj.related_id, s1.pk)
+
+        # You can use 'pk' with reverse foreign key lookups.
+        self.assert_delayed(s1.primary_set.all().only('pk')[0], 3)
+
+        self.assert_delayed(qs.defer("name").extra(select={"a": 1})[0], 1)
+        self.assert_delayed(qs.extra(select={"a": 1}).defer("name")[0], 1)
+        self.assert_delayed(qs.defer("name").defer("value")[0], 2)
+        self.assert_delayed(qs.only("name").only("value")[0], 2)
+        self.assert_delayed(qs.only("name").defer("value")[0], 2)
+        self.assert_delayed(qs.only("name", "value").defer("value")[0], 2)
+        self.assert_delayed(qs.defer("name").only("value")[0], 2)
+
+        obj = qs.only()[0]
+        self.assert_delayed(qs.defer(None)[0], 0)
+        self.assert_delayed(qs.only("name").defer(None)[0], 0)
+
+        # User values() won't defer anything (you get the full list of
+        # dictionaries back), but it still works.
+        self.assertEqual(qs.defer("name").values()[0], {
+            "id": p1.id,
+            "name": "p1",
+            "value": "xx",
+            "related_id": s1.id,
+        })
+        self.assertEqual(qs.only("name").values()[0], {
+            "id": p1.id,
+            "name": "p1",
+            "value": "xx",
+            "related_id": s1.id,
+        })
+
+        # Using defer() and only() with get() is also valid.
+        self.assert_delayed(qs.defer("name").get(pk=p1.pk), 1)
+        self.assert_delayed(qs.only("name").get(pk=p1.pk), 2)
+
+        # When we defer a field and also select_related it, the query is
+        # invalid and raises an exception.
+        with self.assertRaises(InvalidQuery):
+            qs.only("name").select_related("related")[0]
+        with self.assertRaises(InvalidQuery):
+            qs.defer("related").select_related("related")[0]
+
+        # With a depth-based select_related, all deferred ForeignKeys are
+        # deferred instead of traversed.
+        with self.assertNumQueries(3):
+            obj = qs.defer("related").select_related()[0]
+            self.assert_delayed(obj, 1)
+            self.assertEqual(obj.related.id, s1.pk)
+
+        # Saving models with deferred fields is possible (but inefficient,
+        # since every field has to be retrieved first).
+        obj = Primary.objects.defer("value").get(name="p1")
+        obj.name = "a new name"
+        obj.save()
+        self.assertQuerysetEqual(
+            Primary.objects.all(), [
+                "a new name",
+            ],
+            lambda p: p.name
+        )
+
+        # Regression for #10572 - A subclass with no extra fields can defer
+        # fields from the base class
+        Child.objects.create(name="c1", value="foo", related=s1)
+        # You can defer a field on a baseclass when the subclass has no fields
+        obj = Child.objects.defer("value").get(name="c1")
+        self.assert_delayed(obj, 1)
+        self.assertEqual(obj.name, "c1")
+        self.assertEqual(obj.value, "foo")
+        obj.name = "c2"
+        obj.save()
+
+        # You can retrive a single column on a base class with no fields
+        obj = Child.objects.only("name").get(name="c2")
+        self.assert_delayed(obj, 3)
+        self.assertEqual(obj.name, "c2")
+        self.assertEqual(obj.value, "foo")
+        obj.name = "cc"
+        obj.save()
+
+        BigChild.objects.create(name="b1", value="foo", related=s1, other="bar")
+        # You can defer a field on a baseclass
+        obj = BigChild.objects.defer("value").get(name="b1")
+        self.assert_delayed(obj, 1)
+        self.assertEqual(obj.name, "b1")
+        self.assertEqual(obj.value, "foo")
+        self.assertEqual(obj.other, "bar")
+        obj.name = "b2"
+        obj.save()
+
+        # You can defer a field on a subclass
+        obj = BigChild.objects.defer("other").get(name="b2")
+        self.assert_delayed(obj, 1)
+        self.assertEqual(obj.name, "b2")
+        self.assertEqual(obj.value, "foo")
+        self.assertEqual(obj.other, "bar")
+        obj.name = "b3"
+        obj.save()
+
+        # You can retrieve a single field on a baseclass
+        obj = BigChild.objects.only("name").get(name="b3")
+        self.assert_delayed(obj, 4)
+        self.assertEqual(obj.name, "b3")
+        self.assertEqual(obj.value, "foo")
+        self.assertEqual(obj.other, "bar")
+        obj.name = "b4"
+        obj.save()
+
+        # You can retrieve a single field on a baseclass
+        obj = BigChild.objects.only("other").get(name="b4")
+        self.assert_delayed(obj, 4)
+        self.assertEqual(obj.name, "b4")
+        self.assertEqual(obj.value, "foo")
+        self.assertEqual(obj.other, "bar")
+        obj.name = "bb"
+        obj.save()
+
+    def test_defer_proxy(self):
+        """
+        Ensure select_related together with only on a proxy model behaves
+        as expected. See #17876.
+        """
+        related = Secondary.objects.create(first='x1', second='x2')
+        ChildProxy.objects.create(name='p1', value='xx', related=related)
+        children = ChildProxy.objects.all().select_related().only('id', 'name')
+        self.assertEqual(len(children), 1)
+        child = children[0]
+        self.assert_delayed(child, 2)
+        self.assertEqual(child.name, 'p1')
+        self.assertEqual(child.value, 'xx')
+
+    def test_defer_inheritance_pk_chaining(self):
+        """
+        When an inherited model is fetched from the DB, its PK is also fetched.
+        When getting the PK of the parent model it is useful to use the already
+        fetched parent model PK if it happens to be available. Tests that this
+        is done.
+        """
+        s1 = Secondary.objects.create(first="x1", second="y1")
+        bc = BigChild.objects.create(name="b1", value="foo", related=s1,
+                                     other="bar")
+        bc_deferred = BigChild.objects.only('name').get(pk=bc.pk)
+        with self.assertNumQueries(0):
+            bc_deferred.id
+        self.assertEqual(bc_deferred.pk, bc_deferred.id)