C#•4d ago

✅ .NET 8 enum to string serialization throws an exception

Hello, Following the docs, a custom JsonSerializerContext is applied on the controllers, yet an exception is thrown.

c#
public sealed record GetLinkMetricsRequest
{
    [FromRoute]
    public string Id { get; set; }
    
    [FromQuery]
    public TimePeriodUnit? TimeUnit { get; set; } = TimePeriodUnit.Day;
    
    [FromQuery]
    public int? Units { get; set; }
}

[JsonSourceGenerationOptions(UseStringEnumConverter = true)]
[JsonSerializable(typeof(GetLinkMetricsRequest))]
public partial class TimePeriodUnitJsonContext : JsonSerializerContext;


// applied to the Controllers
var options = new JsonSerializerOptions
{
    TypeInfoResolver = JsonTypeInfoResolver.Combine(ContextA.Default, ContextB.Default, ContextC.Default);
};

c#
public sealed record GetLinkMetricsRequest
{
    [FromRoute]
    public string Id { get; set; }
    
    [FromQuery]
    public TimePeriodUnit? TimeUnit { get; set; } = TimePeriodUnit.Day;
    
    [FromQuery]
    public int? Units { get; set; }
}

[JsonSourceGenerationOptions(UseStringEnumConverter = true)]
[JsonSerializable(typeof(GetLinkMetricsRequest))]
public partial class TimePeriodUnitJsonContext : JsonSerializerContext;


// applied to the Controllers
var options = new JsonSerializerOptions
{
    TypeInfoResolver = JsonTypeInfoResolver.Combine(ContextA.Default, ContextB.Default, ContextC.Default);
};

The exception:

An unexpected error occurred. See the inner exception for details. System.NotSupportedException: JsonTypeInfo metadata for type 'AnalyticsService.Api..' was not provided by TypeInfoResolver of type 'System.Text.Json.Serialization.Metadata.JsonTypeInfoResolverWithAddedModifiers'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.

An unexpected error occurred. See the inner exception for details. System.NotSupportedException: JsonTypeInfo metadata for type 'AnalyticsService.Api..' was not provided by TypeInfoResolver of type 'System.Text.Json.Serialization.Metadata.JsonTypeInfoResolverWithAddedModifiers'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.

I have followed the docs: https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/source-generation#combine-source-generators https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/source-generation#blanket-policy

How to use source generation in System.Text.Json - .NET

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9 Replies

Pobiega•4d ago

'AnalyticsService.Api..' doesn't strike me as a valid type identifier especially that double dot at the end is mighty suspicious whats the fully qualified name for GetLinkMetricsRequest?

CoreOP•4d ago

sorry, I had no idea that's relevant

c#
'AnalyticsService.Api.Features.LinkMetrics.Models.GetLinkMetricsResult`1[AnalyticsService.Api.Features.LinkMetrics.Models.LinkClicksByDateResult]'

c#
'AnalyticsService.Api.Features.LinkMetrics.Models.GetLinkMetricsResult`1[AnalyticsService.Api.Features.LinkMetrics.Models.LinkClicksByDateResult]'

Pobiega•4d ago

ok so its in that namespace at least but that seems to be a generic version? GetLinkMetricsResult<T>

CoreOP•4d ago

That's being returned, specifically GetLinkMetricsResult<LinkClicksByDateResult>

c#
public class GetLinkMetricsResult<T>
{
    public IEnumerable<T> Metrics { get; set; } = null!;
}

public class LinkClicksByDateResult : ILinkMetricsResult
{
    public int Clicks { get; set; }
    public LocalDate Date { get; set; }
}

c#
public class GetLinkMetricsResult<T>
{
    public IEnumerable<T> Metrics { get; set; } = null!;
}

public class LinkClicksByDateResult : ILinkMetricsResult
{
    public int Clicks { get; set; }
    public LocalDate Date { get; set; }
}

But there is no enum being used here and it is the response

Pobiega•4d ago

but that type is what the serializer cant serialize thats the error you are getting meaning it (probably) handles the request fine, its the result thats failing

CoreOP•4d ago

Yes, the result is failing the request is serialized

Pobiega•4d ago

okay, so add the result type to your serializer context?

CoreOP•4d ago

Now it works, thank you, I still don't understand what has the response to do with the serializer $close

MODiX•4d ago

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✅ .NET 8 enum to string serialization throws an exception