asp.net-web-api - OWIN 中间件中的全局异常处理

Question

我正在尝试在 ASP.NET Web API 2.1 项目中创建统一的错误处理/报告，该项目构建在 OWIN 中间件(使用 Owin.Host.SystemWeb 的 IIS 主机)之上。
目前我使用了一个自定义异常记录器，它继承自 System.Web.Http.ExceptionHandling.ExceptionLogger并使用 NLog 记录所有异常，如下代码:

public class NLogExceptionLogger : ExceptionLogger
{

    private static readonly Logger Nlog = LogManager.GetCurrentClassLogger();
    public override void Log(ExceptionLoggerContext context)
    {
       //Log using NLog
    } 
}

我想将所有 API 异常的响应正文更改为友好的统一响应，该响应使用 System.Web.Http.ExceptionHandling.ExceptionHandler 隐藏所有异常详细信息如以下代码:

public class ContentNegotiatedExceptionHandler : ExceptionHandler
{
    public override void Handle(ExceptionHandlerContext context)
    {
        var errorDataModel = new ErrorDataModel
        {
            Message = "Internal server error occurred, error has been reported!",
            Details = context.Exception.Message,
            ErrorReference = context.Exception.Data["ErrorReference"] != null ? context.Exception.Data["ErrorReference"].ToString() : string.Empty,
            DateTime = DateTime.UtcNow
        };

        var response = context.Request.CreateResponse(HttpStatusCode.InternalServerError, errorDataModel);
        context.Result = new ResponseMessageResult(response);
    }
}

这将在发生异常时为客户端返回以下响应:

{
  "Message": "Internal server error occurred, error has been reported!",
  "Details": "Ooops!",
  "ErrorReference": "56627a45d23732d2",
  "DateTime": "2015-12-27T09:42:40.2982314Z"
}

现在，如果发生任何异常，这一切都很好 在 Api Controller 请求管道中 .

但在我的情况下，我使用的是中间件 Microsoft.Owin.Security.OAuth用于生成不记名 token ，并且此中间件对 Web API 异常处理一无所知，例如，如果在方法 ValidateClientAuthentication 中抛出了异常我的 NLogExceptionLogger不是 ContentNegotiatedExceptionHandler将了解有关此异常的任何信息，也不会尝试处理它，这是我在 AuthorizationServerProvider 中使用的示例代码如下:

public class AuthorizationServerProvider : OAuthAuthorizationServerProvider
{
    public override Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
    {
        //Expcetion occurred here
        int x = int.Parse("");

        context.Validated();
        return Task.FromResult<object>(null);
    }

    public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
    {
        if (context.UserName != context.Password)
        {
            context.SetError("invalid_credentials", "The user name or password is incorrect.");
            return;
        }

        var identity = new ClaimsIdentity(context.Options.AuthenticationType);

        identity.AddClaim(new Claim(ClaimTypes.Name, context.UserName));

        context.Validated(identity);
    }
}

因此，我将不胜感激在实现以下两个问题方面的任何指导:

1 - 创建一个全局异常处理程序 仅处理 OWIN 中间件生成的异常 ?我关注了 this answer并创建了一个用于异常处理目的的中间件并将其注册为第一个，我能够记录源自“OAuthAuthorizationServerProvider”的异常，但我不确定这是否是最佳方法。

2 - 现在，当我在上一步中实现日志记录时，我真的不知道如何更改异常的响应，因为我需要向客户端返回一个标准的 JSON 模型，以处理“OAuthAuthorizationServerProvider”中发生的任何异常。有相关 answer here我试图依赖，但没有奏效。

这是我的 Startup 类和自定义 GlobalExceptionMiddleware我为异常捕获/记录而创建。缺少的和平是为任何异常返回统一的 JSON 响应。任何想法将不胜感激。

public class Startup
{
    public void Configuration(IAppBuilder app)
    {
        var httpConfig = new HttpConfiguration();

        httpConfig.MapHttpAttributeRoutes();

        httpConfig.Services.Replace(typeof(IExceptionHandler), new ContentNegotiatedExceptionHandler());

        httpConfig.Services.Add(typeof(IExceptionLogger), new NLogExceptionLogger());

        OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
        {
            AllowInsecureHttp = true,
            TokenEndpointPath = new PathString("/token"),
            AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
            Provider = new AuthorizationServerProvider()
        };

        app.Use<GlobalExceptionMiddleware>();

        app.UseOAuthAuthorizationServer(OAuthServerOptions);
        app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());

        app.UseWebApi(httpConfig);
    }
}

public class GlobalExceptionMiddleware : OwinMiddleware
{
    public GlobalExceptionMiddleware(OwinMiddleware next)
        : base(next)
    { }

    public override async Task Invoke(IOwinContext context)
    {
        try
        {
            await Next.Invoke(context);
        }
        catch (Exception ex)
        {
            NLogLogger.LogError(ex, context);
        }
    }
}

Answer 1

好的，所以这比预期的要容易，感谢@Khalid 的提醒，我最终创建了一个名为 OwinExceptionHandlerMiddleware 的 owin 中间件它专门用于处理任何 Owin 中间件中发生的任何异常(在将其返回给客户端之前记录它并处理响应)。

您需要将此中间件注册为 第一个 在 Startup类如下:

public class Startup
{
    public void Configuration(IAppBuilder app)
    {
        var httpConfig = new HttpConfiguration();

        httpConfig.MapHttpAttributeRoutes();

        httpConfig.Services.Replace(typeof(IExceptionHandler), new ContentNegotiatedExceptionHandler());

        httpConfig.Services.Add(typeof(IExceptionLogger), new NLogExceptionLogger());

        OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
        {
            AllowInsecureHttp = true,
            TokenEndpointPath = new PathString("/token"),
            AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
            Provider = new AuthorizationServerProvider()
        };

        //Should be the first handler to handle any exception happening in OWIN middlewares
        app.UseOwinExceptionHandler();

        // Token Generation
        app.UseOAuthAuthorizationServer(OAuthServerOptions);

        app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());

        app.UseWebApi(httpConfig);
    }
}

以及 OwinExceptionHandlerMiddleware中使用的代码如下:

using AppFunc = Func<IDictionary<string, object>, Task>;

public class OwinExceptionHandlerMiddleware
{
    private readonly AppFunc _next;

    public OwinExceptionHandlerMiddleware(AppFunc next)
    {
        if (next == null)
        {
            throw new ArgumentNullException("next");
        }

        _next = next;
    }

    public async Task Invoke(IDictionary<string, object> environment)
    {
        try
        {
            await _next(environment);
        }
        catch (Exception ex)
        {
            try
            {

                var owinContext = new OwinContext(environment);

                NLogLogger.LogError(ex, owinContext);

                HandleException(ex, owinContext);

                return;
            }
            catch (Exception)
            {
                // If there's a Exception while generating the error page, re-throw the original exception.
            }
            throw;
        }
    }
    private void HandleException(Exception ex, IOwinContext context)
    {
        var request = context.Request;

        //Build a model to represet the error for the client
        var errorDataModel = NLogLogger.BuildErrorDataModel(ex);

        context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
        context.Response.ReasonPhrase = "Internal Server Error";
        context.Response.ContentType = "application/json";
        context.Response.Write(JsonConvert.SerializeObject(errorDataModel));

    }

}

public static class OwinExceptionHandlerMiddlewareAppBuilderExtensions
{
    public static void UseOwinExceptionHandler(this IAppBuilder app)
    {
        app.Use<OwinExceptionHandlerMiddleware>();
    }
}