aspnetcore: Cannot use JSON source generator with (HttpValidation)ProblemDetails

Is there an existing issue for this?

I have searched the existing issues

Describe the bug

If the JSON source generator is enabled for the default JSON serializer options and an application uses the Results.Problem() or Results.ValidationProblem() methods, it is not possible to make the two work together.

If the HttpValidationProblemDetails or ProblemDetails is not registered with the JsonSerializerContext, then an exception is thrown at runtime:

NotSupportedException: Metadata for type 'Microsoft.AspNetCore.Mvc.ProblemDetails' was not provided by TypeInfoResolver of type 'ApplicationJsonSerializerContext'. If using source generation, ensure that all root types passed to the serializer have been indicated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.

If a developer attempts to add either type using [JsonSerializable], then the application fails to compile:

Project\Repro\System.Text.Json.SourceGeneration\System.Text.Json.SourceGeneration.JsonSourceGenerator\ApplicationJsonSerializerContext.ProblemDetails.g.cs(24,120): error CS0122: 'ProblemDetailsJsonConverter' is inaccessible due to its protection level

Expected Behavior

An application is successfully able to use Results.Problem() or Results.ValidationProblem() with JSON source generators and Minimal APIs.

Steps To Reproduce

A full repro project is available at martincostello/problemdetails-json-source-generator-repro.

To reproduce, clone the project and run dotnet build.

Exceptions (if any)

No response

.NET Version

7.0.100-preview.7.22377.5

Anything else?

I think something somewhere in the JSON source generator has become more strict beginning in .NET 7 preview 7, which is what brought this to my attention.

Previously I think the source generator would just fallback to using runtime serialization so things would “just work” without you needing to add the [JsonSerializable] attribute.

It seems like it would be fairly trivial to fix this use case by making HttpValidationProblemDetailsJsonConverter and ProblemDetailsJsonConverter public instead of internal, but as they’re shared source that might cause other complications with multiple public types with the same name and namespace in different assemblies.

About this issue

Original URL
State: closed
Created 2 years ago
Comments: 23 (17 by maintainers)

Most upvoted comments

@martincostello https://github.com/dotnet/aspnetcore/issues/44132 is completed and you should be able from .NET 8 Preview 2 source-gen a problemdetails, if needed

brunolins16 on Feb 24, 2023

FWIW I should say that adding reflection-based fallback defeats the purpose of using source generators. It seems unfortunate that we need to rely on reflection (accidentally in .NET 6, explicitly starting with .NET 7) to add serialization support for the validation models. It sounds to me like MVC might want to expose a JsonSerializerContext for common model types so that users can add them to the mix without relying on reflection:

builder.Services.ConfigureRouteHandlerJsonOptions((options) =>
{
    options.TypeInfoResolver = JsonTypeInfoResolver.Combine(ApplicationJsonSerializerContext.Default, ValidationContext.Default);
});

cc @davidfowl

eiriktsarpalis on Aug 22, 2022

If the HttpValidationProblemDetails or ProblemDetails is not registered with the JsonSerializerContext, then an exception is thrown at runtime:

This seems related to an intentional breaking change we made in Preview 7. See https://github.com/dotnet/runtime/issues/71714 for more details and a workaround.

If a developer attempts to add either type using [JsonSerializable], then the application fails to compile:

The error message appears related to a bug fixed recently in https://github.com/dotnet/runtime/issues/71714, cc @krwq.

eiriktsarpalis on Aug 19, 2022

@martincostello In .NET 8, we changed to when AddProblemDetails is called we combine our internal ProblemDetailsJsonContext, so, in most cases that will be enough. However, I am still trying to have this https://github.com/dotnet/aspnetcore/issues/44132 that will allow add ProblemDetails to your JsonContext

brunolins16 on Jan 26, 2023

Would that also fix this source gen issue?

The problem (at least in my case) is that I’m using source-gen with my MVC API. By default HttpValidation/Validation/ProblemDetails all cause serialization to fail since they’ve not been defined on the JsonSerializerContext I’ve bound to Mvc’s JsonOptions.

The work-around is to enable the reflection-fallback but that seems like it defeats the purpose. If aspnet exposed a JsonSerializerContext for the *ProblemDetails types we can combine that with our own context without needing to enable the reflection-fallback mode.

pinkfloydx33 on Aug 24, 2022

@martincostello I worked with the JSON source generation for problem details when developing the ProblemDetailsService and just to let you know that probably you will face another problem when it is fixed because, by default, it will not fallback to reflection-based the Extensions property fail to serialize.

https://github.com/dotnet/aspnetcore/blob/7cb457bdaac8de9214391a9b9b273821d01c2300/src/Http/Http.Extensions/src/DefaultProblemDetailsWriter.cs#L54

Unless if you knowo all types that will be there at runtime and added then to your context.

https://docs.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-source-generation?pivots=dotnet-6-0#source-generation-support-in-aspnet-core

brunolins16 on Aug 12, 2022