c# - 引用标准库后异常不会进入 ExceptionFilter

Question

我在 .NET 4.6.1 上有一个传统的 WebApi 项目，它有一个全局 ExceptionFilter，它处理已知异常以返回带有相应状态代码的友好消息。

WebApiConfig.cs

public static void Register(HttpConfiguration config)
{
    config.MapHttpAttributeRoutes();

    config.Routes.MapHttpRoute(
        name: "DefaultApi",
        routeTemplate: "api/{controller}/{id}",
        defaults: new { id = RouteParameter.Optional }
    );

    config.Filters.Add(new MyExceptionFilterAttribute());
}

MyExceptionFilterAttribute.cs

internal sealed class GatewayExceptionFilterAttribute : ExceptionFilterAttribute
{
    private static readonly Dictionary<Type, HttpStatusCode> Exceptions = new Dictionary<Type, HttpStatusCode>
    {
        // HTTP 400
        [typeof(ArgumentException)] = HttpStatusCode.BadRequest,
        [typeof(ArgumentNullException)] = HttpStatusCode.BadRequest,
    };

    public override void OnException(HttpActionExecutedContext context)
    {
        var type = context.Exception.GetType();

        if (context.Exception is HttpResponseException)
            return;

        // Return 500 for unspecified errors
        var status = HttpStatusCode.InternalServerError;
        var message = Strings.ERROR_INTERNAL_ERROR;

        if (Exceptions.ContainsKey(type))
        {
            status = Exceptions[type];
            message = context.Exception.Message;
        }

        context.Response = context.Request.CreateErrorResponse(status, message);
    }
}

MyController.cs

public class MyController : ApiController
{
    public async Task<IHttpActionResult> Get()
    {
        await Task.Run(() => { throw new ArgumentNullException("Error"); });
        return Ok();
    }
}

按原样调用时，我将收到 400。

但是，当添加对 .NETStandard 2.0 库的引用时，异常不会转到 ExceptionFilter 并且我收到以下错误:

{
    "message": "An error has occurred.",
    "exceptionMessage": "Method not found: 'System.Net.Http.HttpRequestMessage System.Web.Http.Filters.HttpActionExecutedContext.get_Request()'.",
    "exceptionType": "System.MissingMethodException",
    "stackTrace": "   at MyApi.Filters.MyExceptionFilterAttribute.OnException(HttpActionExecutedContext context)\r\n   at System.Web.Http.Filters.ExceptionFilterAttribute.OnExceptionAsync(HttpActionExecutedContext actionExecutedContext, CancellationToken cancellationToken)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.ExceptionFilterAttribute.<ExecuteExceptionFilterAsyncCore>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Controllers.ExceptionFilterResult.<ExecuteAsync>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()"
}

感谢任何帮助。

Answer 1

我在使用 .Net 4.6.2 Web API 时遇到了同样的问题。我在 Web 项目中定义了以下异常处理程序:

public class ExceptionHandlerAttribute : ExceptionFilterAttribute
{
    private readonly MyLogger _logger;

    private const string ExceptionOccuredLoggingTag = "ExceptionOccured";

    public ExceptionHandlerAttribute(MyLogger logger)
    {
        _logger = logger;
    }


    public override void OnException(HttpActionExecutedContext context)
    {
        ...
        _logger.Error(errorMessage,
            context.Exception,
            mostRecentFrame.Class.Name,
            mostRecentFrame.Method.Name,
            ExceptionOccuredLoggingTag);
        ...
    }
}

在另一个 .NETStandart 2.0 dll 中定义了 MyLogger 类。在尝试调用它时，它向我显示了与上面相同的异常。

这里对我有用的解决方法是在 Web 项目引用的另一个库(非 .NETStandart 2.0)中定义一个 .Net 框架适配器 MyLoggerAdapter(在我的例子中是业务层库):

public interface ILoggerCompatable
{
    void Error(string message, object data, params string[] tags);
}

public class MyLoggerAdapter : ILoggerCompatable
{
    private readonly MyLogger _logger;

    public MyLoggerAdapter(MyLogger logger)
    {
        _logger = logger;
    }

    public void Error(string message, object data, params string[] tags) => _logger.Error(message, data, tags.Select(tag => (Tag)tag).ToArray());
}

因此从源 .NETStandart 库中看不到任何内容，然后将其注入(inject)处理程序(通过 Autofac):

public class ExceptionHandlerAttribute : ExceptionFilterAttribute
{
    private readonly ILoggerCompatable _logger;

    private const string ExceptionOccuredLoggingTag = "ExceptionOccured";

    public ExceptionHandlerAttribute(ILoggerCompatable logger)
    {
        _logger = logger;
    }


    public override void OnException(HttpActionExecutedContext context)
    {
        ...
        _logger.Error(errorMessage,
            context.Exception,
            mostRecentFrame.Class.Name,
            mostRecentFrame.Method.Name,
            ExceptionOccuredLoggingTag);
        ...);
    }
}

过滤器注册看起来像这样:

var loggerCompatable = GlobalConfiguration.Configuration.DependencyResolver.GetService(typeof(ILoggerCompatable)) as ILoggerCompatable;
GlobalConfiguration.Configuration.Filters.Add(new ExceptionHandlerAttribute(loggerCompatable));

希望这对您有所帮助!