JsonTypeInfoExtensions.GetSchemaReferenceId throws ArgumentOutOfRangeException for nested generic types

[kl1mm]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hey together,
i have a constellation similar to the following:

...
app.Services.AddOpenApi();
...
app.MapOpenApi();

app.MapGet("/foo", () => new Foo<int>.Bar<string>.Baz { One = 1, Two = "hello" });

public static class Foo<T>
{
    public static class Bar<TT>
    {
        public class Baz
        {
            public required T One { get; set; }
            public required TT Two { get; set; }
        }
    }
}

When I try to access the generated openapi.json in the browser via http://<server>:<port>/openapi/v1.json I get an ArgumentOutOfRangeException.

The problem seems to be located in this part:

// The typesystem says Baz is a generic type but the name property does not have any ` characters 
// because it is nested and the declaring type is the generic one.

if (type.IsGenericType)
{
    var genericTypeName = type.Name[..type.Name.LastIndexOf('`')];
    var genericArguments = type.GetGenericArguments();
    var argumentNames = string.Join("And", genericArguments.Select(arg => arg.GetSchemaReferenceId(options)));
    return $"{genericTypeName}Of{argumentNames}";
}

Expected Behavior

Do not throw an exception and return either Baz or even better FooOfInt.BarOfString.Baz

Steps To Reproduce

No response

Exceptions (if any)

System.ArgumentOutOfRangeException    at System.ArgumentOutOfRangeException.ThrowNegative[T](T value, String paramName)
   at System.ArgumentOutOfRangeException.ThrowIfNegative[T](T value, String paramName)
   at System.String.ThrowSubstringArgumentOutOfRange(Int32 startIndex, Int32 length)
   at System.String.Substring(Int32 startIndex, Int32 length)
   at Microsoft.AspNetCore.OpenApi.JsonTypeInfoExtensions.GetSchemaReferenceId(Type type, JsonSerializerOptions options)
   at Microsoft.AspNetCore.OpenApi.JsonTypeInfoExtensions.GetSchemaReferenceId(JsonTypeInfo jsonTypeInfo, Boolean isTopLevel)
   at Microsoft.AspNetCore.OpenApi.OpenApiOptions.CreateDefaultSchemaReferenceId(JsonTypeInfo jsonTypeInfo)
   at Microsoft.AspNetCore.OpenApi.JsonNodeSchemaExtensions.ApplySchemaReferenceId(JsonNode schema, JsonSchemaExporterContext context, Func`2 createSchemaReferenceId)
   at Microsoft.AspNetCore.OpenApi.OpenApiSchemaService.\u003C\u003Ec__DisplayClass0_0.\u003C.ctor\u003Eb__2(JsonSchemaExporterContext context, JsonNode schema)
   at System.Text.Json.Schema.JsonSchema.\u003CToJsonNode\u003Eg__CompleteSchema|104_0(JsonNode schema, \u003C\u003Ec__DisplayClass104_0&)
   at System.Text.Json.Schema.JsonSchema.ToJsonNode(JsonSchemaExporterOptions options)
   at System.Text.Json.Schema.JsonSchemaExporter.GetJsonSchemaAsNode(JsonTypeInfo typeInfo, JsonSchemaExporterOptions exporterOptions)
   at System.Text.Json.Schema.JsonSchemaExporter.GetJsonSchemaAsNode(JsonSerializerOptions options, Type type, JsonSchemaExporterOptions exporterOptions)
   at Microsoft.AspNetCore.OpenApi.OpenApiSchemaService.CreateSchema(OpenApiSchemaKey key)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at Microsoft.AspNetCore.OpenApi.OpenApiSchemaStore.GetOrAdd(OpenApiSchemaKey key, Func`2 valueFactory)
   at Microsoft.AspNetCore.OpenApi.OpenApiSchemaService.GetOrCreateSchemaAsync(Type type, IServiceProvider scopedServiceProvider, IOpenApiSchemaTransformer[] schemaTransformers, ApiParameterDescription parameterDescription, Boolean captureSchemaByRef, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.OpenApi.OpenApiDocumentService.GetResponseAsync(ApiDescription apiDescription, Int32 statusCode, ApiResponseType apiResponseType, IServiceProvider scopedServiceProvider, IOpenApiSchemaTransformer[] schemaTransformers, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.OpenApi.OpenApiDocumentService.GetResponsesAsync(ApiDescription description, IServiceProvider scopedServiceProvider, IOpenApiSchemaTransformer[] schemaTransformers, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.OpenApi.OpenApiDocumentService.GetOperationAsync(ApiDescription description, HashSet`1 capturedTags, IServiceProvider scopedServiceProvider, IOpenApiSchemaTransformer[] schemaTransformers, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.OpenApi.OpenApiDocumentService.GetOperationsAsync(IGrouping`2 descriptions, HashSet`1 capturedTags, IServiceProvider scopedServiceProvider, IOpenApiOperationTransformer[] operationTransformers, IOpenApiSchemaTransformer[] schemaTransformers, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.OpenApi.OpenApiDocumentService.GetOpenApiPathsAsync(HashSet`1 capturedTags, IServiceProvider scopedServiceProvider, IOpenApiOperationTransformer[] operationTransformers, IOpenApiSchemaTransformer[] schemaTransformers, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.OpenApi.OpenApiDocumentService.GetOpenApiDocumentAsync(IServiceProvider scopedServiceProvider, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Builder.OpenApiEndpointRouteBuilderExtensions.\u003C\u003Ec__DisplayClass0_0.\u003C\u003CMapOpenApi\u003Eb__0\u003Ed.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Http.Generated.\u003CGeneratedRouteBuilderExtensions_g\u003EF56B68D2B55B5B7B373BA2E4796D897848BC0F04A969B1AF6260183E8B9E0BAF2__GeneratedRouteBuilderExtensionsCore.\u003C\u003Ec__DisplayClass2_0.\u003C\u003CMapGet0\u003Eg__RequestHandler|5\u003Ed.MoveNext()
--- End of stack trace from previous location ---
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddlewareImpl.\u003CInvoke\u003Eg__Awaited|10_0(ExceptionHandlerMiddlewareImpl middleware, HttpContext context, Task task)

.NET Version

9.0.100

Anything else?

No response

[captainsafia]

@kl1mm Thanks for filing this issue!

Would you be interested in submitting a PR to expand our test suite with this example and make a fix to the default implementation for CreateSchemaReferenceId?

[dotnet-policy-service]

Looks like this issue has been identified as a candidate for community contribution. If you're considering sending a PR for this issue, look for the Summary Comment link in the issue description. That comment has been left by an engineer on our team to help you get started with handling this issue. You can learn more about our Help Wanted process here