Fix persisting null optional complex property with default values

[Pmyl]

When optional complex properties transition from non-null to null with default-valued properties, those default values were not being tracked and therefore not set to null in the database.

This PR builds on top of the fix #37387 that fixes the opposite scenario.

Fixes #37890

[Pmyl]

@dotnet-policy-service agree

[Copilot]

Pull request overview

Fixes change tracking for optional complex properties when transitioning from non-null to null while inner value-type properties are at their CLR defaults, ensuring the database columns are updated to NULL as expected.

Changes:

• Update ChangeDetector.DetectComplexPropertyChange to mark all flattened inner properties as modified on both null→non-null and non-null→null transitions.
• Add a new spec test covering non-null→null transition for an optional complex property with multiple default-valued inner properties.
• Add/adjust provider-specific overrides to skip/route the new test appropriately (SqlServer proxies, InMemory limitation, Cosmos async-only).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/EFCore/ChangeTracking/Internal/ChangeDetector.cs	Marks inner complex properties as modified when nullable complex reference toggles null/non-null, ensuring persistence of nulling out columns.
test/EFCore.Specification.Tests/ComplexTypesTrackingTestBase.cs	Adds coverage for setting an optional multi-property complex to null after saving default-valued inner properties.
test/EFCore.SqlServer.FunctionalTests/ComplexTypesTrackingSqlServerTest.cs	Skips the new test for proxies scenario due to notification change tracking limitation (#36175).
test/EFCore.InMemory.FunctionalTests/ComplexTypesTrackingInMemoryTest.cs	Skips the new test due to existing InMemory complex-type query/materialization limitations (#31464).
test/EFCore.Cosmos.FunctionalTests/CosmosComplexTypesTrackingTest.cs	Routes the new test through the async-only Cosmos path (skip sync).

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[Copilot]

Pull request overview

Fixes change tracking for optional (nullable) complex properties when transitioning from non-null to null, ensuring that inner properties with default values are treated as modified so database columns are correctly set to NULL.

Changes:

• Update ChangeDetector.DetectComplexPropertyChange to mark all flattened inner properties as modified when a nullable complex property changes nullness in either direction (null ↔ non-null).
• Add a new specification test covering non-null → null transitions for optional complex properties with default-valued inner properties.
• Skip/route the new test appropriately for providers/scenarios where the underlying capability isn’t supported (InMemory, SQL Server change-tracking proxies, Cosmos sync).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/EFCore/ChangeTracking/Internal/ChangeDetector.cs	Marks inner complex properties as modified when a nullable complex property changes nullness (handles non-null → null scenario).
test/EFCore.Specification.Tests/ComplexTypesTrackingTestBase.cs	Adds coverage for nulling an optional complex property whose inner properties are default values.
test/EFCore.SqlServer.FunctionalTests/ComplexTypesTrackingSqlServerTest.cs	Skips the new test for SQL Server change-tracking proxy scenario (known limitation).
test/EFCore.InMemory.FunctionalTests/ComplexTypesTrackingInMemoryTest.cs	Skips the new test for InMemory provider due to existing complex-type limitations.
test/EFCore.Cosmos.FunctionalTests/CosmosComplexTypesTrackingTest.cs	Routes the new test through async path only (Cosmos doesn’t support sync operations).

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[Copilot]

Pull request overview

Fixes change tracking for optional complex properties when transitioning from non-null → null, ensuring inner properties with CLR default values are still treated as modified so database columns get set to NULL. This complements the earlier null → non-null fix in #37387.

Changes:

• Update ChangeDetector.DetectComplexPropertyChange to mark inner properties modified for both nullability transitions (null ↔ non-null).
• Add a new specification test covering non-null → null for an optional multi-property complex type with default-valued inner properties.
• Skip or adapt the new test for providers/fixtures with known limitations (InMemory, SQL Server proxies, Cosmos sync), and add Cosmos cleanup logic.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/EFCore/ChangeTracking/Internal/ChangeDetector.cs	Extends complex-property null transition detection to mark inner properties modified for non-null → null as well.
test/EFCore.Specification.Tests/ComplexTypesTrackingTestBase.cs	Adds a new cross-provider test validating persistence when optional complex is set to null.
test/EFCore.SqlServer.FunctionalTests/ComplexTypesTrackingSqlServerTest.cs	Skips the new test for the proxies fixture due to notification change tracking limitations.
test/EFCore.InMemory.FunctionalTests/ComplexTypesTrackingInMemoryTest.cs	Skips the new test due to known InMemory complex-type limitations.
test/EFCore.Cosmos.FunctionalTests/CosmosComplexTypesTrackingTest.cs	Runs the new test async-only and attempts cleanup after execution strategy completion.

---

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[Copilot]

Pull request overview

Fixes EF Core change tracking for optional complex properties when transitioning from non-null to null, ensuring inner properties with CLR default values are treated as modified and persisted as NULL in the database (issue #37890), complementing #37387.

Changes:

• Update complex-property change detection to mark inner properties as modified for both null→non-null and non-null→null transitions.
• Add a new specification test covering non-null→null transitions with default-valued inner properties.
• Add/adjust provider-specific overrides (skip for InMemory/proxy SqlServer; async-only for Cosmos) and ensure Cosmos test cleanup runs in a finally.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/EFCore/ChangeTracking/Internal/ChangeDetector.cs	Marks complex type inner properties as modified when an optional complex property toggles null/non-null.
test/EFCore.Specification.Tests/ComplexTypesTrackingTestBase.cs	Adds regression test for non-null→null with default-valued inner properties.
test/EFCore.SqlServer.FunctionalTests/ComplexTypesTrackingSqlServerTest.cs	Skips the new test for the proxy-based fixture (notification tracking limitation).
test/EFCore.InMemory.FunctionalTests/ComplexTypesTrackingInMemoryTest.cs	Skips the new test due to existing InMemory complex-type limitations.
test/EFCore.Cosmos.FunctionalTests/CosmosComplexTypesTrackingTest.cs	Runs new test only for async; guarantees DB cleanup via try/finally.

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[AndriySvyryd]

Thanks for your contribution!