Cosmos: Complex properties binding

[JoasE]

Adds a CosmosStructuralTypeMaterializerSource and overrides AddStructuralTypeInitialization in CosmosShapedQueryCompilingExpressionVisitor to generate materialization expressions for complex properties
Leverages Nullable<>.HasValue for nullable value types in to support value types without equals operator
Part of: #31253

[Copilot]

Pull request overview

This pull request implements binding logic for complex properties in the Cosmos DB provider, enabling proper materialization of complex types from JSON documents. The implementation introduces a custom CosmosStructuralTypeMaterializerSource that defers complex property handling to allow nested materialization expressions to be generated during query compilation.

Key changes:

• Introduces CosmosStructuralTypeMaterializerSource to control when complex properties are materialized during shaping
• Implements nested complex property and collection binding in CosmosShapedQueryCompilingExpressionVisitor
• Enhances null-handling logic in CosmosProjectionBindingExpressionVisitor for nullable value types

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
src/EFCore.Cosmos/Query/Internal/CosmosStructuralTypeMaterializerSource.cs	New class that overrides complex type materialization behavior to enable deferred binding
src/EFCore.Cosmos/Query/Internal/CosmosShapedQueryCompilingExpressionVisitor.cs	Adds logic to generate materialization expressions for complex properties and collections from JObject/JArray
src/EFCore.Cosmos/Query/Internal/CosmosShapedQueryCompilingExpressionVisitor.CosmosProjectionBindingRemovingExpressionVisitorBase.cs	Exposes methods and fields needed for complex property binding; adds handling for ComplexPropertyBindingExpression
src/EFCore.Cosmos/Query/Internal/CosmosProjectionBindingExpressionVisitor.cs	Improves null-safety checks for nullable value types and refactors member expression updates
src/EFCore.Cosmos/Extensions/CosmosServiceCollectionExtensions.cs	Registers the new CosmosStructuralTypeMaterializerSource service
test/EFCore.Cosmos.FunctionalTests/CosmosComplexTypesTrackingTest.cs	Uncomments assertions that now pass with complex property binding implemented
test/EFCore.Cosmos.FunctionalTests/Query/Associations/ComplexProperties/ComplexPropertiesProjectionCosmosTest.cs	New test class with Cosmos-specific overrides for complex property projection tests
test/EFCore.Cosmos.FunctionalTests/Query/Associations/ComplexProperties/ComplexPropertiesCosmosFixture.cs	Test fixture configuration for complex properties tests in Cosmos

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

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

[roji]

Hey @JoasE, thanks for submitting this and sorry I haven't gotten around to reviewing it earlier.

I admit that this part of the Cosmos query pipeline is generally unfamiliar to me, and also represents an older/legacy part of the EF codebase in general. I'll do my best to fully understand everything and provide meaningful feedback. As we add more test coverage I'm sure issues will be flushed out.

For now, here's a first round of review comments - most are nits but see some more important things as well.

[Copilot]

Pull request overview

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

[roji]

@JoasE just a note - when you've handled a review comment, please resolve it to keep track of comments that still need handling (or discussion) vs. those which are completely done.

(I'll re-review very soon)

[JoasE]

@roji friendly reminder in this! No worries if priorities changed :)

[roji]

Yeah, sorry about that - I'll really try to get to it in the next few days (and in general be more reactive to your Cosmos PRs).

[roji]

Finally got around to this, sorry for the delay @JoasE. This looks ready to merge - see the comments below (nothing major). I'll prioritize this (and your other PRs) so we can iterate quickly and built out the support.

[roji]

Thanks @JoasE, looking forward to the follow-up PRs!