System.Text.Json cannot serialise EF Core Model with foreign key constraint

[sipsorcery]

Description

The model generated by EF Core for a 2 table database with a foreign key constraint cannot be serialised by System.Text.Json. The exception thrown is:

System.Text.Json.JsonException: A possible object cycle was detected. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 32. Consider using ReferenceHandler.Preserve on JsonSerializerOptions to support cycles.

This scenario would seem to be a minimal use case for ASP.NET Core Web API + EF Core and ideally should work without requiring workarounds.

Configuration

Visual Studio 2019 16.8.3

c:\Tools>dotnet --info
.NET SDK (reflecting any global.json):
 Version:   5.0.101
 Commit:    d05174dc5a

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19042
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.101\

Host (useful for support):
  Version: 5.0.1
  Commit:  b02e13abab

Replication Steps

• Create an SQL database with a foreign key constraint:

begin transaction;

create table domain
(
 id uniqueidentifier not null,
 domain nvarchar(128) not null,	
 Primary Key(id),
);

create table account
(
 id uniqueidentifier not null,
 domainid uniqueidentifier not null,
 username nvarchar(128) not null,
 Primary Key(id),
 Foreign Key(domainid) references domain(id)
);

insert into domain values ('BA497780-8AF0-42F1-97E7-DF1153FAAD16', 'test1');
insert into account values (newid(), 'BA497780-8AF0-42F1-97E7-DF1153FAAD16', 'user1');

commit;

• Create a new ASP.NET Core Web Application using the Visual Studio 2019 template. Select ASP.NET Core Web API on the configuration screen,

• Add EF Core packages to solution
  dotnet add package Microsoft.EntityFrameworkCore.Design
dotnet add package Microsoft.EntityFrameworkCore.SqlServer

• Add EF Core model to ASP.NET project
  dotnet ef dbcontext scaffold "Data Source=localhost;Initial Catalog=EFTest;Persist Security Info=True;User ID=appuser;Password=password" Microsoft.EntityFrameworkCore.SqlServer -o Models

• Add new controller to ASP.NET project API -> API Controller with actions, using Entity Framework. For the Model class select the Domain class corresponding to the SQL table created in the first step along with the matching Data context class.

• Make the following code changes to the ASP.NET project:
  In Startup.cs:

// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
   services.AddDbContext<AspNetEFTest2.Models.EFTestContext>();
   services.AddControllers();
}

In Models\DomainControllers.cs

// GET: api/Domains
[HttpGet]
public async Task<ActionResult<IEnumerable<Domain>>> GetDomains()
{
    return await _context.Domains.Include(x => x.Accounts).ToListAsync();
}

• Attempt to list the Domain records using the controller:
  curl -X GET "http://localhost:5000/api/Domains"

• The ASP.NET application throws System.Text.Json.JsonException.

System.Text.Json.JsonException: A possible object cycle was detected. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 32. Consider using ReferenceHandler.Preserve on JsonSerializerOptions to support cycles.

• Apply the recommendation in the exception message by setting ReferenceHandler.Preserve on JsonSerializerOptions.
  In Startup.cs:

// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
	services.AddControllers().AddJsonOptions(options => {
		options.JsonSerializerOptions.ReferenceHandler = System.Text.Json.Serialization.ReferenceHandler.Preserve;

	});
	services.AddDbContext<AspNetEFTest2.Models.EFTestContext>();
	services.AddControllers();
}

• Attempt to list the Domain records using the controller. The JSON produced is "polluted" with additional fields that make it difficult to consume.
  curl -X GET "http://localhost:5000/api/Domains"

{"$id":"1","$values":[{"$id":"2","id":"ba497780-8af0-42f1-97e7-df1153faad16","domain1":"test1","accounts":{"$id":"3","$values":[{"$id":"4","id":"f0d314b0-f4e6-4a90-ac70-186b7d624422","domainid":"ba497780-8af0-42f1-97e7-df1153faad16","username":"user1","domain":{"$ref":"2"}}]}}]}

Other information

Exception stack trace:

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1] An unhandled exception has occurred while executing the request. System.Text.Json.JsonException: A possible object cycle was detected. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 32. Consider using ReferenceHandler.Preserve on JsonSerializerOptions to support cycles. at System.Text.Json.ThrowHelper.ThrowJsonException_SerializerCycleDetected(Int32 maxDepth) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ICollectionOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonPropertyInfo1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.ListOfTConverter2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonSerializer.WriteCore[TValue](JsonConverter jsonConverter, Utf8JsonWriter writer, TValue& value, JsonSerializerOptions options, WriteStack& state) at System.Text.Json.JsonSerializer.WriteAsyncCore[TValue](Stream utf8Json, TValue value, Type inputType, JsonSerializerOptions options, CancellationToken cancellationToken) at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|29_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters() --- End of stack trace from previous location --- at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger) at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Workaround

Replace System.Text.Json with Newtonsoft.

• Add Newtonsoft.Json to the ASP.NET project
  dotnet add package Microsoft.AspNetCore.Mvc.NewtonsoftJson

// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
	services.AddControllersWithViews()
		.AddNewtonsoftJson(options =>
		options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
	);
	services.AddDbContext<AspNetEFTest2.Models.EFTestContext>();
	services.AddControllers();
}

• Attempt to list the Domain records using the controller.
  curl -X GET "http://localhost:5000/api/Domains"

[{"id":"ba497780-8af0-42f1-97e7-df1153faad16","domain1":"test1","accounts":[{"id":"f0d314b0-f4e6-4a90-ac70-186b7d624422","domainid":"ba497780-8af0-42f1-97e7-df1153faad16","username":"user1"}]}]

[davidfowl]

I'm not sure that's a work around, that's by design.

[sipsorcery]

If it is by design my guess is I'm not the only developer who will encounter the problem and need to go through the same troubleshooting steps.

Maybe even a tip on the documentation would reduce the friction. Although ideally this simple scenario would work out of the box or have an option that can be applied without having to identify and install new packages.

[huoyaoyuan]

It's documented in EF documentation:
https://docs.microsoft.com/en-us/ef/core/querying/related-data/serialization

[sipsorcery]

Ok, seems like it's "one of those things" that each developer will have to discover for themselves. Hopefully the presence of this issue will make the search a little quicker.