ABP微服务学习系列-修复System.Text.Json不支持序列化Exception

前面我们已经把服务都启动了，然后我们试试请求API。
发现请求出现500


返回错误

System.NotSupportedException: Serialization and deserialization of 'System.Reflection.MethodBase' instances are not supported. Path: $.Exceptions.TargetSite.
 ---> System.NotSupportedException: Serialization and deserialization of 'System.Reflection.MethodBase' instances are not supported.
   at System.Text.Json.Serialization.Converters.UnsupportedTypeConverter`1.Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Converters.ListOfTConverter`2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonCollectionConverter`2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   --- End of inner exception stack trace ---
   at System.Text.Json.ThrowHelper.ThrowNotSupportedException(WriteStack& state, NotSupportedException ex)
   at System.Text.Json.Serialization.JsonConverter`1.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.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteCore[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo`1 jsonTypeInfo)
   at System.Text.Json.JsonSerializer.WriteString[TValue](TValue& value, JsonTypeInfo`1 jsonTypeInfo)
   at Volo.Abp.Json.SystemTextJson.AbpSystemTextJsonSerializer.Serialize(Object obj, Boolean camelCase, Boolean indented)
   at Volo.Abp.RabbitMQ.Utf8JsonRabbitMqSerializer.Serialize(Object obj)
   at Volo.Abp.EventBus.RabbitMq.RabbitMqDistributedEventBus.PublishAsync(Type eventType, Object eventData, IBasicProperties properties, Dictionary`2 headersArguments)
   at Volo.Abp.EventBus.RabbitMq.RabbitMqDistributedEventBus.PublishToEventBusAsync(Type eventType, Object eventData)
   at Volo.Abp.EventBus.Distributed.DistributedEventBusBase.PublishAsync(Type eventType, Object eventData, Boolean onUnitOfWorkComplete, Boolean useOutbox)
   at Volo.Abp.EventBus.UnitOfWorkEventPublisher.PublishDistributedEventsAsync(IEnumerable`1 distributedEvents)
   at Volo.Abp.Uow.UnitOfWork.CompleteAsync(CancellationToken cancellationToken)
   at Volo.Abp.Uow.UnitOfWorkInterceptor.InterceptAsync(IAbpMethodInvocation invocation)
   at Volo.Abp.Castle.DynamicProxy.CastleAsyncAbpInterceptorAdapter`1.InterceptAsync(IInvocation invocation, IInvocationProceedInfo proceedInfo, Func`3 proceed)
   at Volo.Abp.Auditing.AuditingManager.SaveAsync(DisposableSaveHandle saveHandle)
   at Volo.Abp.Auditing.AuditingManager.DisposableSaveHandle.SaveAsync()
   at Volo.Abp.AspNetCore.Auditing.AbpAuditingMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Volo.Abp.AspNetCore.Serilog.AbpSerilogMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Volo.Abp.AspNetCore.Security.Claims.AbpClaimsMapMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Volo.Abp.AspNetCore.Security.AbpSecurityHeadersMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.RequestLocalization.AbpRequestLocalizationMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Volo.Abp.AspNetCore.Tracing.AbpCorrelationIdMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

这是由于接口抛出异常，但是System.Text.Json不支持序列化Exception导致的。
如何解决呢，这里我们需要自己自定义一个ExceptionJsonConverter
在Shared.Hosting.AspNetCore添加JsonConverters目录，新建一个ExceptionJsonConverter类。
类继承JsonConverter泛型接口，并重写他的方法。
完整converter代码如下：

using System;
using System.Linq;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace FunShow.Shared.Hosting.AspNetCore.JsonConverters
{
    public class ExceptionJsonConverter<TExceptionType>: JsonConverter<TExceptionType> where TExceptionType : Exception
    {
        public override bool CanConvert(Type typeToConvert)
        {
            return typeof(Exception).IsAssignableFrom(typeToConvert);
        }

        public override TExceptionType Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            throw new NotSupportedException("Deserializing exceptions is not allowed");
        }

        public override void Write(Utf8JsonWriter writer, TExceptionType value, JsonSerializerOptions options)
        {
            var serializableProperties = value.GetType()
                .GetProperties()
                .Select(uu => new { uu.Name, Value = uu.GetValue(value) })
                .Where(uu => uu.Name != nameof(Exception.TargetSite));

            if (options?.DefaultIgnoreCondition == System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull)
            {
                serializableProperties = serializableProperties.Where(uu => uu.Value != null);
            }

            var propList = serializableProperties.ToList();

            if (propList.Count == 0)
            {
                // Nothing to write
                return;
            }

            writer.WriteStartObject();

            foreach (var prop in propList)
            {
                writer.WritePropertyName(prop.Name);
                JsonSerializer.Serialize(writer, prop.Value, options);
            }

            writer.WriteEndObject();
        }
    }
}

然后在FunShowSharedHostingAspNetCoreModule中添加如下代码：

    public override void ConfigureServices(ServiceConfigurationContext context)
    {
        Configure(options => options.JsonSerializerOptions.Converters.Add(new ExceptionJsonConverter()));
    }

再次请求，我们发现接口HTTP状态码变成了401，没有再次出现序列化不支持的异常了。


我们通过swagger的Authorize获取token之后随便输入再次发出请求，请求再次500，但是500返回内容正常，没有再次出现序列化不支持的异常。


到这我们就解决了System.Text.Json不支持序列化Exception的一个问题。