Cosmos: Add DatabaseFacade extension Deserialize by JoasE · Pull Request #37543 · dotnet/efcore

JoasE · 2026-01-20T13:55:24Z

Implements: #37542

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        Summary of the changes
        - Detail 1
        - Detail 2

        Fixes #bugnumber

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Implements: dotnet#37542

JoasE · 2026-01-20T13:59:04Z

This is a bit "hacky", but it's the simplest/easiest way I could find to implement this. I understand if this way wouldn't be acceptable

Copilot

Pull request overview

This PR adds a new Deserialize method to DatabaseFacade for Cosmos DB that allows deserializing JObject documents into their corresponding entity types. This is particularly useful for scenarios like processing change feed events.

Changes:

Added two Deserialize extension methods (generic and non-generic) to CosmosDatabaseFacadeExtensions
Introduced ICosmosQueryingEnumerable<T> interface to expose the query context and shaper function
Added comprehensive functional tests covering various deserialization scenarios including discriminators and error cases

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File	Description
`src/EFCore.Cosmos/Extensions/CosmosDatabaseFacadeExtensions.cs`	Implements two `Deserialize` extension methods with entity type determination logic and shaper invocation
`src/EFCore.Cosmos/Query/Internal/CosmosShapedQueryCompilingExpressionVisitor.QueryingEnumerable.cs`	Adds `ICosmosQueryingEnumerable<T>` interface and implements it in `QueryingEnumerable<T>` to expose shaper and query context
`test/EFCore.Cosmos.FunctionalTests/Extensions/CosmosDbContextExtensionsDeserializeTest.cs`	Comprehensive test suite covering deserialization scenarios including discriminators, error cases, and change feed processing

src/EFCore.Cosmos/Extensions/CosmosDatabaseFacadeExtensions.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…into feature/dotnet#37542

Copilot

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 7 comments.

Files not reviewed (1)

src/EFCore.Cosmos/Properties/CosmosStrings.Designer.cs: Language not supported

src/EFCore.Cosmos/Extensions/CosmosDatabaseFacadeExtensions.cs

test/EFCore.Cosmos.FunctionalTests/Extensions/CosmosDbContextExtensionsDeserializeTest.cs

…e entity

Copilot

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

Copilot · 2026-01-20T21:14:30Z

test/EFCore.Cosmos.FunctionalTests/Extensions/CosmosDbContextExtensionsDeserializeTest.cs

+    [ConditionalFact]
+    public virtual async Task Changefeed()
+    {
+        using var context = Fixture.CreateContext();
+
+        var client = context.Database.GetCosmosClient();
+        var container = client.GetContainer(
+            context.Database.GetCosmosDatabaseId(),
+            context.Model.GetEntityTypes().First(x => x.IsDocumentRoot()).GetContainer());
+
+        Customer? deserialized = null;
+        var processor = container.GetChangeFeedProcessorBuilder("processor", async (IReadOnlyCollection<JObject> changes, CancellationToken ctx) =>
+        {
+            using var context = Fixture.CreateContext();
+            deserialized = context.Database.Deserialize<Customer>(changes.Single());
+        }).WithInMemoryLeaseContainer().Build();
+
+        await processor.StartAsync();
+        try
+        {
+            var customer = new Customer { Id = Guid.NewGuid().ToString(), Name = "Customer 1", PartitionKey = "1" };
+            customer.Children.Add(new DummyChild { Id = "1", Name = "Child 1" });
+            context.Customers.Add(customer);
+
+            await context.SaveChangesAsync();
+
+            var counter = 0;
+            while (deserialized == null && counter++ < 30)
+            {
+                await Task.Delay(1000);
+            }
+            Assert.NotNull(deserialized);
+
+            Assert.Equal(customer.Name, deserialized.Name);
+            Assert.Equal(customer.Id, deserialized.Id);
+        }


The test creates a Customer entity with owned children but only verifies the parent entity properties after deserialization. The test should also verify that the Children collection is properly populated to ensure owned entities are correctly deserialized in the change feed scenario.

Copilot · 2026-01-20T21:14:30Z

src/EFCore.Cosmos/Extensions/CosmosDatabaseFacadeExtensions.cs

 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.

+using System;


The using directive for System is unnecessary and should be removed. The code uses ArgumentNullException.ThrowIfNull and ArgumentException.ThrowIfNullOrWhiteSpace which are available in the global namespace through implicit usings in the project.

Suggested change

using System;

Copilot · 2026-01-20T21:14:30Z

src/EFCore.Cosmos/Extensions/CosmosDatabaseFacadeExtensions.cs

 // The .NET Foundation licenses this file to you under the MIT license.

+using System;
+using System.Reflection.Metadata;


The using directive for System.Reflection.Metadata is unused and should be removed. No types from this namespace are referenced in the code.

Suggested change

using System.Reflection.Metadata;

Copilot · 2026-01-20T21:14:30Z

src/EFCore.Cosmos/Extensions/CosmosDatabaseFacadeExtensions.cs

 using Microsoft.EntityFrameworkCore.Cosmos.Storage.Internal;
+using Microsoft.EntityFrameworkCore.Query.Internal;
+using Newtonsoft.Json.Linq;
+using static Microsoft.EntityFrameworkCore.DbLoggerCategory;


The static using directive for DbLoggerCategory is unused and should be removed. No members from DbLoggerCategory are referenced in the code.

Suggested change

using static Microsoft.EntityFrameworkCore.DbLoggerCategory;

Copilot · 2026-01-20T21:14:31Z

test/EFCore.Cosmos.FunctionalTests/Extensions/CosmosDbContextExtensionsDeserializeTest.cs

+    [ConditionalFact]
+    public virtual async Task Deserializes()
+    {
+        using var context = Fixture.CreateContext();
+
+        var customer = new Customer { Id = Guid.NewGuid().ToString(), Name = "Customer 1", PartitionKey = "1" };
+        customer.Children.Add(new DummyChild { Id = "1", Name = "Child 1" });
+        context.Customers.Add(customer);
+        await context.SaveChangesAsync();
+
+        var client = context.Database.GetCosmosClient();
+        var container = client.GetContainer(
+            context.Database.GetCosmosDatabaseId(),
+            context.Model.GetEntityTypes().First(x => x.IsDocumentRoot()).GetContainer());
+
+        var response = await container.ReadItemAsync<JObject>(customer.Id, new Microsoft.Azure.Cosmos.PartitionKey(customer.PartitionKey));
+        var jObject = response.Resource;
+
+        var deserialized = context.Database.Deserialize<Customer>(jObject);
+
+        Assert.Equal(customer.Name, deserialized.Name);
+        Assert.Equal(customer.Id, deserialized.Id);
+    }


The test creates a Customer entity with owned children but only verifies the parent entity properties after deserialization. The test should also verify that the Children collection is properly populated with the expected DummyChild entity to ensure owned entities are correctly deserialized.

roji · 2026-01-27T15:51:55Z

Closing for now as per #37542 (comment).

Add database facade extension Deserialize

6cbbee6

Implements: dotnet#37542

JoasE added 3 commits January 20, 2026 15:01

Add typed extension method Deserialize

ebc3309

Rename context to match test

16b4f32

Rename test

1a639b0

JoasE marked this pull request as ready for review January 20, 2026 14:05

JoasE requested a review from a team as a code owner January 20, 2026 14:05

Copilot AI review requested due to automatic review settings January 20, 2026 14:05

JoasE marked this pull request as draft January 20, 2026 14:05

Copilot started reviewing on behalf of JoasE January 20, 2026 14:05 View session

Copilot AI reviewed Jan 20, 2026

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JoasE and others added 5 commits January 20, 2026 21:17

Apply suggestions from code review

b5ed485

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Add test

7fc0ec1

Merge branch 'feature/dotnet#37542' of https://github.com/JoasE/efcore …

0a6aee2

…into feature/dotnet#37542

Use CosmosStrings and update tests

2975747

Update docs

11c41a0

JoasE requested a review from Copilot January 20, 2026 20:40

Copilot started reviewing on behalf of JoasE January 20, 2026 20:40 View session

Copilot AI reviewed Jan 20, 2026

View reviewed changes

Move away from generic deserialization and add support for shared typ…

0cc426b

…e entity

JoasE requested a review from Copilot January 20, 2026 21:04

Copilot started reviewing on behalf of JoasE January 20, 2026 21:05 View session

Regenerate template and cleanup tests

aa43d33

Copilot AI reviewed Jan 20, 2026

View reviewed changes

roji closed this Jan 27, 2026

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roji commented Jan 27, 2026

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JoasE commented Jan 20, 2026 •

edited

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