Cosmos: Modernize materializer & subdocument projectionbinding by JoasE · Pull Request #38550 · dotnet/efcore

JoasE · 2026-07-02T12:44:02Z

Materialize query results using Utf8JsonReader
Bind projections of embedded types and remove client projection distinct limitations
Remove __jObject backing property
Require projecting out primary key values for owned projections using AsNoTrackingWithIdentityResolution
Throw for any undefined non-value projection (Cosmos: Anonymous and dto projections filter undefined implicitly when projecting a single property #38298 (comment))
Truncate floating point numbers when materializing to fixed point types instead of rounding (Cosmos: Materializer rounds when deserializing floating point numbers as fixed point numbers #38138)

Part of: #34567
Implements: #34067
Fixes: #38138 , #31696

…Improve

…otnet#34567-Materialization

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src/EFCore.Cosmos/Properties/CosmosStrings.Designer.cs: Generated file

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AndriySvyryd · 2026-07-08T15:51:12Z

@AndriySvyryd Thoughts on this?

You can skip these for the Linux emulator for now. But if they say that this is by design we'll have to rethink our approach.

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src/EFCore/Storage/Json/JsonReaderData.cs:89

In stream mode, the leftover-buffer logic uses buffer.Length rather than _bytesAvailable to determine how much valid data remains after totalConsumed. If a stream read returns fewer bytes than the buffer length (common near EOF and possible with non-buffered streams), this will copy uninitialized/stale bytes and overstate _bytesAvailable, corrupting subsequent JSON parsing.

AndriySvyryd · 2026-07-13T21:04:37Z


 // ReSharper disable once CheckNamespace

+


Extra empty line

AndriySvyryd · 2026-07-14T05:10:35Z

+
+            // Add undefined and null checks for pk on root document
+            // This only throws for root document entity types now, see Old_still_works
+            // @TODO: discuss?


Is there anything left to discuss here?

Good spot! I only wanted to check whether this behavior is correct, which is:
Throw CreateNullKeyValueInNoTracking exception if any primary key value of a root document is null or undefined, not throwing an exception for null key values for owned types and using the ordinal or CLR default value instead.

However, now that I am rubber ducking this, tracking might actually warrant a different exception, and if the owned type isn't one to many (So there is no ordinal), it should probably still throw.

Does that sound right?

AndriySvyryd · 2026-07-14T05:17:20Z

        writer.WriteStartObject();

-        foreach (var property in structuralType.GetProperties())
+        // TODO: Get a better way to order the discriminator property first, without having to special case it here.


File an issue for this

I've created: #38619

JoasE added 30 commits April 16, 2026 10:44

Fix do not translate non-persisted properties

984208d

Add tests

62730cc

Copy over fix for ToList projections

d33a451

Implement ReadItem and Paging enumarators

f48d075

Allow inheritance hiarchies in JsonEntityMaterializerRewriter? TODO: …

4d937b8

…Improve

Non value projections TODO: Improve

7bc7bd5

Numbers and mathematics

b7d16f8

Fix inheritance

d524374

WIP

4e4fa83

WIP

f91a45c

WIP

654ae55

WIP

c9e0b86

WIP

611d8a6

WIP

0c6a507

WIP

fecd0d0

WIP

fd1adb8

Revert changes

5ab9c5e

WIP: Working non collections

99dc183

Fix nested collection

fe499e6

WIP: CollectionShaper?

1fd10b8

Fix owned mappings

5747ad1

Select method

9c4de60

Select_nested_collection_on_optional_associate

865a911

ShapedQueryCompilingExpressionVisitor fix?

4bc3bcc

Fix tracking variable

04a1dba

Fix ownerMappings

b3960d7

Fix entityEntry

d2adfb0

Merge branch 'feature/dotnet#34067-ProjectSubDocuments' into feature/d…

a0802db

…otnet#34567-Materialization

Fix merge conflicts

aa3b472

WIP subquery

fe18c49

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Comment thread test/EFCore.Tests/Storage/Json/JsonReaderDataTest.cs

Comment thread ...Core.Cosmos/Query/Internal/CosmosShapedQueryCompilingExpressionVisitor.QueryingEnumerable.cs

JoasE added 3 commits July 8, 2026 13:24

Add test and change comment

0cc5bd7

Fix nullables for projection numbers

622cdc0

Clean

dfaaf34

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Comment thread test/EFCore.Cosmos.FunctionalTests/Query/AdHocJsonQueryCosmosTest.cs Outdated

JoasE added 2 commits July 8, 2026 14:00

Clean null discriminator case

783a1cf

Use default for for reading null properties (matches 10.0) and add tests

a086163

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Comment thread src/EFCore.Cosmos/Extensions/Internal/CosmosResponseStreamHelper.cs

Comment thread ...smosShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.ClientMethods.cs

JoasE commented Jul 8, 2026

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Comment thread src/EFCore.Cosmos/Query/Internal/CosmosProjectionBindingExpressionVisitor.cs Outdated

JoasE requested a review from AndriySvyryd July 8, 2026 13:25

Remove todo: done

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Comment thread src/EFCore.Cosmos/Query/Internal/Expressions/CollectionShaperExpression.cs Outdated

Comment thread test/EFCore.Cosmos.FunctionalTests/Query/ComplexTypeQueryCosmosTest.cs

Comment thread test/EFCore.Cosmos.FunctionalTests/Query/ComplexTypeToJsonPropertyQueryCosmosTest.cs

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AndriySvyryd mentioned this pull request Jul 13, 2026

Document Cosmos JSON breaking changes dotnet/EntityFramework.Docs#5421

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JoasE commented Jul 2, 2026 •

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