Fix OriginalValues.ToObject for added complex collections

[thromel]

Fixes #38486

Problem

OriginalValues.ToObject() can throw for an entity in the Added state when the entity contains a complex collection. Scalar original values already fall back to current values for added entries, but complex collection reconstruction was still trying to read element entries by original ordinal.

For added entities, complex collection elements do not have usable original ordinals. Calling GetComplexCollectionOriginalEntry(...) therefore throws before ToObject() can materialize the value graph.

Change

This updates OriginalPropertyValues so complex collection reconstruction uses current complex collection entries when the containing entry is in the Added state. For non-added entries, the existing original-entry reconstruction path is preserved so modified and unchanged entities continue to reconstruct from original snapshots.

The added-state branch also avoids creating per-element original snapshots, since the result is materialized through CurrentPropertyValues and those snapshots would not be read.

Tests

Adds a regression test for OriginalValues.ToObject() on an added entity with:

• a complex collection
• a nested complex collection inside one of the collection elements
• assertions that the returned object graph is cloned rather than sharing the tracked complex element instances

Validation:

• dotnet build test/EFCore.Tests/EFCore.Tests.csproj --no-restore
• dotnet artifacts/bin/EFCore.Tests/Debug/net11.0/Microsoft.EntityFrameworkCore.Tests.dll --filter-method Microsoft.EntityFrameworkCore.ChangeTracking.Internal.PropertyValuesTest.OriginalValues_ToObject_with_complex_collection_for_added_entity --no-progress --no-ansi
• dotnet artifacts/bin/EFCore.Tests/Debug/net11.0/Microsoft.EntityFrameworkCore.Tests.dll --filter-class Microsoft.EntityFrameworkCore.ChangeTracking.Internal.PropertyValuesTest --no-progress --no-ansi

[Copilot]

Pull request overview

Fixes a regression where OriginalValues.ToObject() throws for entities in the Added state when they contain a complex collection, by falling back to current complex-collection entries (consistent with how original values already fall back to current values for added entities).

Changes:

• Update complex-collection reconstruction in OriginalPropertyValues to use current entries for Added entities.
• Add a regression test covering OriginalValues.ToObject() on an Added entity with a complex collection (including nested complex collections).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
test/EFCore.Tests/ChangeTracking/Internal/PropertyValuesTest.cs	Adds a regression test ensuring OriginalValues.ToObject() works for Added entities with complex collections.
src/EFCore/ChangeTracking/Internal/OriginalPropertyValues.cs	Adjusts complex-collection element reconstruction to use current entries for Added entities to avoid missing original ordinals.

[AndriySvyryd]

Thanks for your contribution!

[s-reithmeir-hundegger-com]

is there any way to get this into a efcore 10.. release, or is the update policy only for 11..?

[AndriySvyryd]

@s-reithmeir-hundegger-com This issue hasn't been reported by enough users to warrant it being backported.