#34634: Creating objects with nested MTI crashes.
-------------------------------------+-------------------------------------
Reporter: Mariusz Felisiak | Owner: Akash
| Kumar Sen
Type: Bug | Status: assigned
Component: Database layer | Version: 4.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Simon Charette):
It feels like `ItalianRestaurantManyParents` should not be allowed to be
defined in the first place since `place_ptr` conflicts.
For example the following model cannot be defined
{{{#!diff
diff --git a/tests/model_inheritance/models.py
b/tests/model_inheritance/models.py
index dc0e238f7e..9b25ac4b8a 100644
--- a/tests/model_inheritance/models.py
+++ b/tests/model_inheritance/models.py
@@ -110,6 +110,9 @@ class Supplier(Place):
customers = models.ManyToManyField(Restaurant,
related_name="provider")
+class Foo(Supplier, Restaurant):
+ pass
+
class CustomSupplier(Supplier):
pass
}}}
{{{
model_inheritance.Bob: (models.E005) The field 'place_ptr' from parent
model 'model_inheritance.supplier' clashes with the field 'place_ptr' from
parent model 'model_inheritance.restaurant'.
}}}
I would expect a similar crash when defining
`ItalianRestaurantManyParents` about a conflicting `place_ptr`.
Once the model is appropriately defined to avoid the conflicting parent
link the creation succeeds with an extra query
{{{#!diff
diff --git a/tests/model_inheritance/models.py
b/tests/model_inheritance/models.py
index dc0e238f7e..c303a97d04 100644
--- a/tests/model_inheritance/models.py
+++ b/tests/model_inheritance/models.py
@@ -106,6 +106,12 @@ class ItalianRestaurant(Restaurant):
serves_gnocchi = models.BooleanField(default=False)
+class ItalianRestaurantManyParents(ItalianRestaurant, Place):
+ place_two_ptr = models.OneToOneField(
+ Place, on_delete=models.CASCADE, parent_link=True
+ )
+
+
class Supplier(Place):
customers = models.ManyToManyField(Restaurant,
related_name="provider")
diff --git a/tests/model_inheritance/tests.py
b/tests/model_inheritance/tests.py
index 4542e6c3cc..0ed9d2f14e 100644
--- a/tests/model_inheritance/tests.py
+++ b/tests/model_inheritance/tests.py
@@ -25,6 +25,7 @@
Supplier,
Title,
Worker,
+ ItalianRestaurantManyParents,
)
@@ -149,6 +150,13 @@ def test_custompk_m2m(self):
# accidentally found).
self.assertSequenceEqual(s.titles.all(), [])
+ def test_create_diamond_mti_common_parents(self):
+ with self.assertNumQueries(5):
+ ItalianRestaurantManyParents.objects.create(
+ name="Ristorante Miron",
+ address="1234 W. Ash",
+ )
+
def test_update_parent_filtering(self):
"""
Updating a field of a model subclass doesn't issue an UPDATE
}}}
{{{
1. INSERT INTO "model_inheritance_place" ("name", "address") VALUES ('',
'') RETURNING "model_inheritance_place"."id"
2. INSERT INTO "my_restaurant" ("place_ptr_id", "rating",
"serves_hot_dogs", "serves_pizza", "chef_id") VALUES (1, NULL, 0, 0, NULL)
3. INSERT INTO "model_inheritance_italianrestaurant" ("restaurant_ptr_id",
"serves_gnocchi") VALUES (1, 0)
4. UPDATE "model_inheritance_place" SET "name" = '', "address" = '' WHERE
"model_inheritance_place"."id" = 1
5. INSERT INTO "model_inheritance_italianrestaurantmanyparents"
("italianrestaurant_ptr_id", "place_two_ptr_id") VALUES (1, 1)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/34634#comment:10>
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