Unwrap django lazy objects in mutation resolvers (#338)

Co-authored-by: Thiago Bellini Ribeiro <[email protected]>

strawberry_django/mutations/resolvers.py

@@ -23,6 +23,7 @@
     ManyToOneRel,
     OneToOneRel,
 )
+from django.utils.functional import LazyObject
 from strawberry import UNSET, relay
 from typing_extensions import Literal, TypeAlias, TypedDict
 
@@ -214,9 +215,9 @@ def create(
 
 @transaction.atomic
 def create(
-    info,
-    model,
-    data,
+    info: Info,
+    model: type[_M],
+    data: dict[str, Any] | list[dict[str, Any]],
     *,
     full_clean: bool | FullCleanOptions = True,
     pre_save_hook: Callable[[_M], None] | None = None,
@@ -262,13 +263,18 @@ def update(
 
 @transaction.atomic
 def update(
-    info,
-    instance,
-    data,
+    info: Info,
+    instance: _M | Iterable[_M],
+    data: dict[str, Any],
     *,
     full_clean: bool | FullCleanOptions = True,
     pre_save_hook: Callable[[_M], None] | None = None,
-):
+) -> _M | list[_M]:
+    # Unwrap lazy objects since they have a proxy __iter__ method that will make
+    # them iterables even if the wrapped object isn't
+    if isinstance(instance, LazyObject):
+        instance = cast(_M, instance.__reduce__()[1][0])
+
     if isinstance(instance, Iterable):
         many = True
         instances = list(instance)
@@ -346,7 +352,7 @@ def update(
 
         full_clean_options = full_clean if isinstance(full_clean, dict) else {}
         if full_clean:
-            instance.full_clean(**full_clean_options)
+            instance.full_clean(**full_clean_options)  # type: ignore
 
         instance.save()
 
@@ -379,7 +385,12 @@ def delete(
 
 
 @transaction.atomic
-def delete(info, instance, *, data=None):
+def delete(info: Info, instance: _M | Iterable[_M], *, data=None) -> _M | list[_M]:
+    # Unwrap lazy objects since they have a proxy __iter__ method that will make
+    # them iterables even if the wrapped object isn't
+    if isinstance(instance, LazyObject):
+        instance = cast(_M, instance.__reduce__()[1][0])
+
     if isinstance(instance, Iterable):
         many = True
         instances = list(instance)

tests/mutations/conftest.py

@@ -3,6 +3,7 @@
 import pytest
 import strawberry
 from django.conf import settings
+from django.utils.functional import SimpleLazyObject
 from strawberry import auto
 
 import strawberry_django
@@ -35,6 +36,27 @@ class Mutation:
         FruitPartialInput,
         filters=FruitFilter,
     )
+
+    @strawberry_django.mutation
+    def update_lazy_fruit(self, info, data: FruitPartialInput) -> Fruit:
+        fruit = SimpleLazyObject(lambda: models.Fruit.objects.get())
+        return mutations.resolvers.update(
+            info,
+            fruit,
+            mutations.resolvers.parse_input(
+                info,
+                vars(data),
+            ),
+        )
+
+    @strawberry_django.mutation
+    def delete_lazy_fruit(self, info) -> Fruit:
+        fruit = SimpleLazyObject(lambda: models.Fruit.objects.get())
+        return mutations.resolvers.delete(
+            info,
+            fruit,
+        )
+
     delete_fruits: List[Fruit] = mutations.delete(filters=FruitFilter)
 
     create_color: Color = mutations.create(ColorInput)
@@ -64,3 +86,8 @@ class GeoMutation(Mutation):
         mutation = Mutation
 
     return utils.generate_query(mutation=mutation)
+
+
+@pytest.fixture()
+def fruit(db):
+    return models.Fruit.objects.create(name="Strawberry")

tests/mutations/test_mutations.py

@@ -57,6 +57,14 @@ def test_update(mutation, fruits):
     ]
 
 
+def test_update_lazy_object(mutation, fruit):
+    result = mutation(
+        '{ fruit: updateLazyFruit(data: { name: "orange" }) { id name } }',
+    )
+    assert not result.errors
+    assert result.data["fruit"] == {"id": "1", "name": "orange"}
+
+
 def test_update_with_filters(mutation, fruits):
     result = mutation(
         '{ fruits: updateFruits(data: { name: "orange" },'
@@ -85,6 +93,13 @@ def test_delete(mutation, fruits):
     assert list(models.Fruit.objects.values("id", "name")) == []
 
 
+def test_delete_lazy_object(mutation, fruit):
+    result = mutation("{ fruit: deleteLazyFruit { id name } }")
+    assert not result.errors
+    assert result.data["fruit"] == {"id": "1", "name": "Strawberry"}
+    assert list(models.Fruit.objects.values("id", "name")) == []
+
+
 def test_delete_with_filters(mutation, fruits):
     result = mutation(
         '{ fruits: deleteFruits(filters: { name: { contains: "berry" } }) { id'

tests/mutations/test_relationship.py

@@ -3,11 +3,6 @@
 from tests import models
 
 
-@pytest.fixture()
-def fruit(db):
-    return models.Fruit.objects.create(name="Strawberry")
-
-
 @pytest.fixture()
 def color(db):
     return models.Color.objects.create(name="red")