当我不使用“System.IntPtr”时，为什么 System.Text.Json 会为“System.IntPtr”抛出“NotSupportedException”？

Question

我有一个 .NET Framework 4.8 / AngularJS 应用程序，我正在尝试升级到 .NET 6，以便我可以开始尝试更新的前端框架（如 Blazor）。升级进展顺利，但当从 Angular JS 代码调用我的 API 方法之一时，我总是看到此错误：

System.NotSupportedException: Serialization and deserialization of 'System.IntPtr' instances are not supported. Path: $.TargetSite.MethodHandle.Value.
 ---> System.NotSupportedException: Serialization and deserialization of 'System.IntPtr' 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.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.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.WriteCore[TValue](JsonConverter jsonConverter, Utf8JsonWriter writer, TValue& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_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.<InvokeFilterPipelineAsync>g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

HEADERS
=======
Accept: application/json, text/plain, */*
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9
Authorization: Negotiate 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
Connection: keep-alive
Content-Length: 346
Content-Type: application/json;charset=UTF-8
Cookie: ai_user=r+bRv|2022-01-12T04:50:58.222Z
Host: localhost:42721
Referer: http://localhost:42721/
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.82 Safari/537.36
sec-ch-ua: " Not A;Brand";v="99", "Chromium";v="98", "Google Chrome";v="98"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"
Origin: http://localhost:42721
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty

我对这个错误感到困惑。API 方法如下所示：

[HttpPost]
public IActionResult Validate([FromBody] ValidationDto dto)
{
    try
    {
        ...
    }
    catch (Exception ex)
    {
        return StatusCode((int)HttpStatusCode.InternalServerError, ex.InnermostException());
    }
}

该类ValidationDto看起来像这样：

public class ValidationDto
{
    public Guid GuidProperty { get; set; }
    public DateTime? NullableDateTimeProperty { get; set; }
    public int IntegerProperty { get; set; }
    public ValidationType EnumProperty { get; set; }
    public bool BooleanProperty { get; set; }
}

枚举ValidationType看起来像这样：

public enum ValidationType
{
    FirstType,
    SecondType,
    ThirdType,
}

我指定的唯一 JSON 选项如下：

var builder = WebApplication.CreateBuilder(args);

builder.Services
    .AddControllers()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.DictionaryKeyPolicy = JsonNamingPolicy.CamelCase;
        options.JsonSerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
    });

哪里可以找到无法反序列化的System.Text.Jsonan ？IntPtr

Answer 1

您的代码在序列化而不是反序列化期间失败，因为您正在捕获一些内部异常并尝试通过在此处返回它来使用 System.Text.Json 对其进行序列化：

return StatusCode((int)HttpStatusCode.InternalServerError, ex.InnermostException());

不幸的是，System.Text.Json 不支持异常的序列化，请参阅System.Text.Json - 无法序列化异常 #43026以及演示小提琴https://dotnetfiddle.net/RrlPQB。它特别尝试序列化TargetSite.MethodHandle.Value，实际上是一个IntPtr.

如果您确实需要返回所有异常数据，您可以编写一个自定义的JsonConverter<Exception>. 但是，以字符串或 DTO 形式返回必要的信息会更容易，如下所示：

return StatusCode((int)HttpStatusCode.InternalServerError, ex.InnermostException().Message);

或者

return StatusCode((int)HttpStatusCode.InternalServerError, ex.InnermostException().ToString());

或者甚至是像这样的匿名类型 DTO：

return StatusCode((int)HttpStatusCode.InternalServerError, new { ex.InnermostException().Message, StackTrace = ex.InnermostException().StackTrace?.ToString()} );

以 JSON 消息形式返回异常具有用于自定义异常返回方式的附加选项。