#36073: Custom field without get_db_prep_value() errors on updates if part of
composite primary key
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Type: Bug
Status: new | Component: Database
| layer (models, ORM)
Version: dev | Severity: Release
| blocker
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
A model with a custom field only implementing `get_db_prep_save()` but not
`get_db_prep_value()` fails on `save()` when used in a composite primary
key, but only for updates. Inserts work fine.
This fell out of #36062 where the test model I adjusted happened to have a
[https://github.com/django/django/blob/a9c79b462923ce366101db1b5a3fff3d1dad870c/tests/serializers/models/base.py#L128-L149
custom field with these characteristics.]
I didn't get as far as verifying this to be relevant, but I noticed while
stepping through the code that `SQLInsertCompiler` has
[https://github.com/django/django/blob/a9c79b462923ce366101db1b5a3fff3d1dad870c/django/db/models/sql/compiler.py#L1814
logic to add `pk` to the list of fields], so I wonder if it's not being
prepared the same way in `SQLUpdateCompiler`?
{{{#!diff
diff --git a/tests/custom_pk/fields.py b/tests/custom_pk/fields.py
index 2d70c6b6dc..135b315ffe 100644
--- a/tests/custom_pk/fields.py
+++ b/tests/custom_pk/fields.py
@@ -59,6 +59,27 @@ class MyWrapperField(models.CharField):
return value
+class MyWrapperFieldWithoutGetDbPrepValue(models.CharField):
+ def to_python(self, value):
+ if not value:
+ return
+ if not isinstance(value, MyWrapper):
+ value = MyWrapper(value)
+ return value
+
+ def from_db_value(self, value, expression, connection):
+ if not value:
+ return
+ return MyWrapper(value)
+
+ def get_db_prep_save(self, value, connection):
+ if not value:
+ return
+ if isinstance(value, MyWrapper):
+ return str(value)
+ return value
+
+
class MyAutoField(models.BigAutoField):
def from_db_value(self, value, expression, connection):
if value is None:
diff --git a/tests/custom_pk/models.py b/tests/custom_pk/models.py
index 000ea7a29d..4ea5190d5f 100644
--- a/tests/custom_pk/models.py
+++ b/tests/custom_pk/models.py
@@ -7,7 +7,7 @@ this behavior by explicitly adding ``primary_key=True`` to
a field.
from django.db import models
-from .fields import MyAutoField, MyWrapperField
+from .fields import MyAutoField, MyWrapperField,
MyWrapperFieldWithoutGetDbPrepValue
class Employee(models.Model):
@@ -40,3 +40,9 @@ class Foo(models.Model):
class CustomAutoFieldModel(models.Model):
id = MyAutoField(primary_key=True)
+
+
+class CompositePKWithoutGetDbPrepValue(models.Model):
+ pk = models.CompositePrimaryKey("id", "tenant")
+ id = MyWrapperFieldWithoutGetDbPrepValue()
+ tenant = models.SmallIntegerField()
diff --git a/tests/custom_pk/tests.py b/tests/custom_pk/tests.py
index 5f865b680a..fa371942e6 100644
--- a/tests/custom_pk/tests.py
+++ b/tests/custom_pk/tests.py
@@ -2,7 +2,7 @@ from django.db import IntegrityError, transaction
from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
from .fields import MyWrapper
-from .models import Bar, Business, CustomAutoFieldModel, Employee, Foo
+from .models import Bar, Business, CompositePKWithoutGetDbPrepValue,
CustomAutoFieldModel, Employee, Foo
class BasicCustomPKTests(TestCase):
@@ -164,6 +164,14 @@ class CustomPKTests(TestCase):
Business.objects.create(name="Bears")
Business.objects.create(pk="Tears")
+ def test_custom_composite_pk_save_force_update(self):
+ """A custom primary key field that implements get_db_prep_save()
+ rather than get_db_prep_value() still saves."""
+ obj = CompositePKWithoutGetDbPrepValue()
+ obj.id = MyWrapper("1")
+ obj.tenant = 1
+ obj.save() # passes with force_insert=True
+
def test_unicode_pk(self):
# Primary key may be Unicode string.
Business.objects.create(name="jaźń")
}}}
----
{{{
ERROR: test_custom_composite_pk_save_force_update
(custom_pk.tests.CustomPKTests.test_custom_composite_pk_save_force_update)
A custom primary key field that implements get_db_prep_save()
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/.../django/django/db/backends/utils.py", line 105, in
_execute
return self.cursor.execute(sql, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/.../django/django/db/backends/sqlite3/base.py", line 360,
in execute
return super().execute(query, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
sqlite3.ProgrammingError: Error binding parameter 3: type 'MyWrapper' is
not supported
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/Users/.../django/tests/custom_pk/tests.py", line 173, in
test_custom_composite_pk_save_force_update
bar.save() # passes with force_insert=True
^^^^^^^^^^
...
File "/Users/.../django/django/db/backends/sqlite3/base.py", line 360,
in execute
return super().execute(query, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
django.db.utils.ProgrammingError: Error binding parameter 3: type
'MyWrapper' is not supported
----------------------------------------------------------------------
Ran 16 tests in 0.011s
FAILED (errors=1, skipped=1)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/36073>
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