Modify bulk update default value (#341)

* Modify bulk update default value

* Patch bulk_update_with_default and add tests

* Remove unused imports

* Change case from default to None

mssql/functions.py

@@ -7,7 +7,7 @@
 from django.core import validators
 from django.db import NotSupportedError, connections, transaction
 from django.db.models import BooleanField, CheckConstraint, Value
-from django.db.models.expressions import Case, Exists, Expression, OrderBy, When, Window
+from django.db.models.expressions import Case, Exists, OrderBy, When, Window
 from django.db.models.fields import BinaryField, Field
 from django.db.models.functions import Cast, NthValue, MD5, SHA1, SHA224, SHA256, SHA384, SHA512
 from django.db.models.functions.datetime import Now
@@ -294,7 +294,7 @@ def _get_check_sql(self, model, schema_editor):
     return sql % tuple(schema_editor.quote_value(p) for p in params)
 
 
-def bulk_update_with_default(self, objs, fields, batch_size=None, default=0):
+def bulk_update_with_default(self, objs, fields, batch_size=None, default=None):
     """
         Update the given fields in each of the given objects in the database.
 
@@ -343,7 +343,8 @@ def bulk_update_with_default(self, objs, fields, batch_size=None, default=0):
                     attr = Value(attr, output_field=field)
                 when_statements.append(When(pk=obj.pk, then=attr))
             if connection.vendor == 'microsoft' and value_none_counter == len(when_statements):
-                case_statement = Case(*when_statements, output_field=field, default=Value(default))
+                # We don't need a case statement if we are setting everything to None
+                case_statement = Value(None)
             else:
                 case_statement = Case(*when_statements, output_field=field)
             if requires_casting:

testapp/migrations/0025_modelwithnullablefieldsofdifferenttypes.py

@@ -0,0 +1,22 @@
+# Generated by Django 5.0.1 on 2024-01-29 14:18
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('testapp', '0024_publisher_book'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ModelWithNullableFieldsOfDifferentTypes',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('int_value', models.IntegerField(null=True)),
+                ('name', models.CharField(max_length=100, null=True)),
+                ('date', models.DateTimeField(null=True)),
+            ],
+        ),
+    ]

testapp/models.py

@@ -54,6 +54,12 @@ class UUIDModel(models.Model):
     def __str__(self):
         return self.pk
 
+class ModelWithNullableFieldsOfDifferentTypes(models.Model):
+    # Issue https://github.com/microsoft/mssql-django/issues/340
+    # Ensures the integrity of bulk updates with different types 
+    int_value = models.IntegerField(null=True)
+    name = models.CharField(max_length=100, null=True)
+    date = models.DateTimeField(null=True)
 
 class TestUniqueNullableModel(models.Model):
     # Issue https://github.com/ESSolutions/django-mssql-backend/issues/38:

testapp/tests/test_expressions.py

@@ -1,6 +1,7 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the BSD license.
 
+import datetime
 from unittest import skipUnless
 
 from django import VERSION
@@ -9,7 +10,8 @@
 from django.test import TestCase, skipUnlessDBFeature
 
 from django.db.models.aggregates import Count
-from ..models import Author, Comment, Post, Editor
+from ..models import Author, Comment, Post, Editor, ModelWithNullableFieldsOfDifferentTypes
+
 
 DJANGO3 = VERSION[0] >= 3
 
@@ -103,3 +105,21 @@ def test_order_by_nulls_first(self):
         self.assertEqual(len(results), 2)
         self.assertIsNone(results[0].alt_editor)
         self.assertIsNotNone(results[1].alt_editor)
+
+class TestBulkUpdate(TestCase):
+     def test_bulk_update_different_column_types(self):
+        data = (
+            (1, 'a', datetime.datetime(year=2024, month=1, day=1)),
+            (2, 'b', datetime.datetime(year=2023, month=12, day=31))
+        )
+        objs = ModelWithNullableFieldsOfDifferentTypes.objects.bulk_create(ModelWithNullableFieldsOfDifferentTypes(int_value=row_data[0],
+                                                                                                                   name=row_data[1],
+                                                                                                                   date=row_data[2]) for row_data in data)
+        for obj in objs:
+            obj.int_value = None
+            obj.name = None
+            obj.date = None
+        ModelWithNullableFieldsOfDifferentTypes.objects.bulk_update(objs, ["int_value", "name", "date"])
+        self.assertCountEqual(ModelWithNullableFieldsOfDifferentTypes.objects.filter(int_value__isnull=True), objs)
+        self.assertCountEqual(ModelWithNullableFieldsOfDifferentTypes.objects.filter(name__isnull=True), objs)
+        self.assertCountEqual(ModelWithNullableFieldsOfDifferentTypes.objects.filter(date__isnull=True), objs)