Use string type mapping when sending null values for JSON column update on SQL Server

[Copilot]

On SQL Server, setting a nullable date/time property (DateTime?, DateOnly?, etc.) inside a JSON-mapped owned entity to null failed with Argument data type date is invalid for argument 3 of json_modify function (SqlException 8116). EF emitted the JSON_MODIFY parameter using the property's native date/datetime type mapping, which JSON_MODIFY rejects — even when the value is null.

entity.Reference.NullDateTimeProp = null;
await context.SaveChangesAsync(); // threw SqlException 8116

Changes

• SqlServerModificationCommand.ProcessSinglePropertyJsonUpdate: when the value is null, retain the property's type mapping only for types JSON_MODIFY accepts directly (string, bool, numeric); otherwise fall back to nvarchar(max) (SqlServerStringTypeMapping.UnicodeDefault). The rendered NULL parameter is independent of its declared type, so results are unchanged for the previously-working cases.

  if (value is null)
  {
      parameters = parameters with
      {
          TypeMapping = propertyProviderClrType == typeof(string)
              || propertyProviderClrType == typeof(bool)
              || propertyProviderClrType.IsNumeric()
                  ? mapping
                  : SqlServerStringTypeMapping.UnicodeDefault
      };
      return;
  }

• Test model: added TestNullableDateTime / TestNullableDateOnly to the shared JSON all-types model, seed data, and AssertAllTypes.

• Tests: added Edit_single_property_nullable_datetime_set_to_null and Edit_single_property_nullable_dateonly_set_to_null to JsonUpdateTestBase, with provider SQL baselines for Sqlite, SQL Server, and the SQL Server JSON-type fixture. Updated the two full-document-serialization baselines affected by the new model properties.

Notes

• Sqlite is unaffected — json_set accepts null parameters of any type — so no provider change was needed there; tests confirm correct behavior.
• SQL Server and JSON-type baselines were derived analytically (no SQL Server instance available in this environment) and warrant CI validation.

[Copilot]

Pull request overview

This PR fixes a SQL Server-specific failure when updating JSON-mapped owned properties to null for date/time CLR types (e.g., DateTime?, DateOnly?). The failure was caused by sending a NULL parameter with an underlying SQL type (e.g., date) that JSON_MODIFY rejects, even when the value is NULL.

Changes:

• Adjust SQL Server JSON single-property update parameter type mapping when the value is null, falling back to nvarchar(max) for types not accepted by JSON_MODIFY.
• Extend the shared JSON “all types” owned model with TestNullableDateTime and TestNullableDateOnly, including seeding and assertions.
• Add/update provider functional tests and SQL baselines for nulling these JSON properties (SqlServer, SqlServer json-type fixture, Sqlite).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/EFCore.SqlServer/Update/Internal/SqlServerModificationCommand.cs	Changes null-parameter type mapping for JSON single-property updates to avoid JSON_MODIFY type rejection.
test/EFCore.Relational.Specification.Tests/Update/JsonUpdateTestBase.cs	Adds new base tests for setting nullable date/time JSON properties to null.
test/EFCore.SqlServer.FunctionalTests/Update/JsonUpdateSqlServerTest.cs	Adds SQL Server baselines for the new nulling tests and updates affected baselines.
test/EFCore.SqlServer.FunctionalTests/Update/JsonUpdateJsonTypeSqlServerTest.cs	Adds SQL Server (json-type fixture) baselines for the new nulling tests and updates affected baselines.
test/EFCore.Sqlite.FunctionalTests/Update/JsonUpdateSqliteTest.cs	Adds SQLite baselines for the new nulling tests and updates affected baselines.
test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonOwnedAllTypes.cs	Adds nullable DateTime/DateOnly properties to the JSON owned type model.
test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonQueryData.cs	Seeds values for the new nullable properties in the shared JSON all-types data.
test/EFCore.Specification.Tests/Query/JsonQueryFixtureBase.cs	Extends AssertAllTypes to include the new nullable date/time properties.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.