Fixed #29413 -- Prevented evaluation of QuerySet.get_or_create()/update_or_create() defaults unless needed.

Removed the logic added in 81e05a418dc6f347d9627373288e773c477a9fe0 which
was obsolete since dbffffa7dc95fc62cbecfd00284bde62ee796f48.

AUTHORS

@@ -849,6 +849,7 @@ answer newbie questions, and generally made Django that much better:
     Vasil Vangelovski
     Victor Andrée
     viestards.lists@gmail.com
+    Viktor Danyliuk <v.v.danyliuk@gmail.com>
     Ville Säävuori <http://www.unessa.net/>
     Vinay Sajip <vinay_sajip@yahoo.co.uk>
     Vincent Foley <vfoleybourgon@yahoo.ca>

django/db/models/query.py

@@ -478,14 +478,14 @@ class QuerySet:
         Return a tuple of (object, created), where created is a boolean
         specifying whether an object was created.
         """
-        lookup, params = self._extract_model_params(defaults, **kwargs)
         # The get() needs to be targeted at the write database in order
         # to avoid potential transaction consistency problems.
         self._for_write = True
         try:
-            return self.get(**lookup), False
+            return self.get(**kwargs), False
         except self.model.DoesNotExist:
-            return self._create_object_from_params(lookup, params)
+            params = self._extract_model_params(defaults, **kwargs)
+            return self._create_object_from_params(kwargs, params)
 
     def update_or_create(self, defaults=None, **kwargs):
         """
@@ -495,13 +495,13 @@ class QuerySet:
         specifying whether an object was created.
         """
         defaults = defaults or {}
-        lookup, params = self._extract_model_params(defaults, **kwargs)
         self._for_write = True
         with transaction.atomic(using=self.db):
             try:
-                obj = self.select_for_update().get(**lookup)
+                obj = self.select_for_update().get(**kwargs)
             except self.model.DoesNotExist:
-                obj, created = self._create_object_from_params(lookup, params)
+                params = self._extract_model_params(defaults, **kwargs)
+                obj, created = self._create_object_from_params(kwargs, params)
                 if created:
                     return obj, created
             for k, v in defaults.items():
@@ -528,15 +528,10 @@ class QuerySet:
 
     def _extract_model_params(self, defaults, **kwargs):
         """
-        Prepare `lookup` (kwargs that are valid model attributes), `params`
-        (for creating a model instance) based on given kwargs; for use by
-        get_or_create() and update_or_create().
+        Prepare `params` for creating a model instance based on the given
+        kwargs; for use by get_or_create() and update_or_create().
         """
         defaults = defaults or {}
-        lookup = kwargs.copy()
-        for f in self.model._meta.fields:
-            if f.attname in lookup:
-                lookup[f.name] = lookup.pop(f.attname)
         params = {k: v for k, v in kwargs.items() if LOOKUP_SEP not in k}
         params.update(defaults)
         property_names = self.model._meta._property_names
@@ -554,7 +549,7 @@ class QuerySet:
                     self.model._meta.object_name,
                     "', '".join(sorted(invalid_params)),
                 ))
-        return lookup, params
+        return params
 
     def _earliest_or_latest(self, *fields, field_name=None):
         """

tests/get_or_create/tests.py

@@ -5,9 +5,8 @@ from threading import Thread
 
 from django.core.exceptions import FieldError
 from django.db import DatabaseError, IntegrityError, connection
-from django.test import (
-    SimpleTestCase, TestCase, TransactionTestCase, skipUnlessDBFeature,
-)
+from django.test import TestCase, TransactionTestCase, skipUnlessDBFeature
+from django.utils.functional import lazy
 
 from .models import (
     Author, Book, DefaultPerson, ManualPrimaryKeyTest, Person, Profile,
@@ -178,6 +177,15 @@ class GetOrCreateTests(TestCase):
             defaults={"birthday": lambda: raise_exception()},
         )
 
+    def test_defaults_not_evaluated_unless_needed(self):
+        """`defaults` aren't evaluated if the instance isn't created."""
+        def raise_exception():
+            raise AssertionError
+        obj, created = Person.objects.get_or_create(
+            first_name='John', defaults=lazy(raise_exception, object)(),
+        )
+        self.assertFalse(created)
+
 
 class GetOrCreateTestsWithManualPKs(TestCase):
 
@@ -443,6 +451,19 @@ class UpdateOrCreateTests(TestCase):
         self.assertIs(created, False)
         self.assertEqual(obj.last_name, 'NotHarrison')
 
+    def test_defaults_not_evaluated_unless_needed(self):
+        """`defaults` aren't evaluated if the instance isn't created."""
+        Person.objects.create(
+            first_name='John', last_name='Lennon', birthday=date(1940, 10, 9)
+        )
+
+        def raise_exception():
+            raise AssertionError
+        obj, created = Person.objects.get_or_create(
+            first_name='John', defaults=lazy(raise_exception, object)(),
+        )
+        self.assertFalse(created)
+
 
 class UpdateOrCreateTestsWithManualPKs(TestCase):
 
@@ -515,15 +536,17 @@ class UpdateOrCreateTransactionTests(TransactionTestCase):
         self.assertEqual(updated_person.last_name, 'NotLennon')
 
 
-class InvalidCreateArgumentsTests(SimpleTestCase):
+class InvalidCreateArgumentsTests(TransactionTestCase):
+    available_apps = ['get_or_create']
     msg = "Invalid field name(s) for model Thing: 'nonexistent'."
+    bad_field_msg = "Cannot resolve keyword 'nonexistent' into field. Choices are: id, name, tags"
 
     def test_get_or_create_with_invalid_defaults(self):
         with self.assertRaisesMessage(FieldError, self.msg):
             Thing.objects.get_or_create(name='a', defaults={'nonexistent': 'b'})
 
     def test_get_or_create_with_invalid_kwargs(self):
-        with self.assertRaisesMessage(FieldError, self.msg):
+        with self.assertRaisesMessage(FieldError, self.bad_field_msg):
             Thing.objects.get_or_create(name='a', nonexistent='b')
 
     def test_update_or_create_with_invalid_defaults(self):
@@ -531,11 +554,11 @@ class InvalidCreateArgumentsTests(SimpleTestCase):
             Thing.objects.update_or_create(name='a', defaults={'nonexistent': 'b'})
 
     def test_update_or_create_with_invalid_kwargs(self):
-        with self.assertRaisesMessage(FieldError, self.msg):
+        with self.assertRaisesMessage(FieldError, self.bad_field_msg):
             Thing.objects.update_or_create(name='a', nonexistent='b')
 
     def test_multiple_invalid_fields(self):
-        with self.assertRaisesMessage(FieldError, "Invalid field name(s) for model Thing: 'invalid', 'nonexistent'"):
+        with self.assertRaisesMessage(FieldError, self.bad_field_msg):
             Thing.objects.update_or_create(name='a', nonexistent='b', defaults={'invalid': 'c'})
 
     def test_property_attribute_without_setter_defaults(self):
@@ -543,5 +566,6 @@ class InvalidCreateArgumentsTests(SimpleTestCase):
             Thing.objects.update_or_create(name='a', defaults={'name_in_all_caps': 'FRANK'})
 
     def test_property_attribute_without_setter_kwargs(self):
-        with self.assertRaisesMessage(FieldError, "Invalid field name(s) for model Thing: 'name_in_all_caps'"):
+        msg = "Cannot resolve keyword 'name_in_all_caps' into field. Choices are: id, name, tags"
+        with self.assertRaisesMessage(FieldError, msg):
             Thing.objects.update_or_create(name_in_all_caps='FRANK', defaults={'name': 'Frank'})