Elmah不使用带有HttpResponseException的WebAPI记录异常

Question

在我的WebApi代码中,我引发了一个HttpResponseException,它将请求管道短路并生成有效的Http响应.但是,我正在尝试将webApi与elmah日志记录集成,但HttpResponseExeptions未显示.

我为elmah设置了web.config并具有以下代码:

在Global.asx.cs中:

static void ConfigureWebApi(HttpConfiguration config)
{  
    config.Filters.Add(new ServiceLayerExceptionFilter());            
    config.Filters.Add(new ElmahHandledErrorLoggerFilter());
    config.DependencyResolver = new WebApiDependencyResolver(ObjectFactory.Container);                            
}     

过滤:

public class ElmahHandledErrorLoggerFilter : ExceptionFilterAttribute
{
    public override void OnException(HttpActionExecutedContext actionExecutedContext)
    {
        base.OnException(actionExecutedContext);
        ErrorSignal.FromCurrentContext().Raise(actionExecutedContext.Exception);
    }
}

引发异常的代码:

public Task<FileUpModel> UploadFile()
{
    if (Request.Content.IsMimeMultipartContent())
    {                
        var provider = new TolMobileFormDataStreamProvider("C:\images\");

        var task = Request.Content.ReadAsMultipartAsync(provider).ContinueWith(
        t =>
        {

            if (t.IsFaulted || t.IsCanceled)
                throw new HttpResponseException(HttpStatusCode.InternalServerError);

            var fileInfo = provider.FileData.FirstOrDefault();
            if (fileInfo == null)
                // the exception here isn't logged by Elmah?!
                throw new HttpResponseException(HttpStatusCode.InternalServerError);    

            var uploadModel = new FileUpModel { success = true };
            return uploadModel;
        });

        return task;
    }
    else
    {
        throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotAcceptable, "This request is not properly formatted"));
    }            
}   

任何实现过这个的人都可以让我知道我做错了什么吗？

Answer 1

如上所述,当您引发HttpResponseException时,Elmah过滤器不捕获并记录任何内容.更具体地说,如果使用以下语法:

return Request.CreateErrorResponse(HttpStatusCode.BadRequest, "It was a bad request");
or
throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotAcceptable, "HttpResponseException - This request is not properly formatted"));

我想在两种情况下陷阱并记录错误.这样做的方法是使用"ActionFilterAttribute",覆盖"OnActionExecuted",并检查actionExecutedContext.Response.IsSuccessStatusCode.

public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
    // when actionExecutedContext.Response is null, the error will be caught and logged by the Elmah filter
    if ((actionExecutedContext.Response != null) && !actionExecutedContext.Response.IsSuccessStatusCode)
    {
        try
        {
            var messages = (System.Web.Http.HttpError)((System.Net.Http.ObjectContent<System.Web.Http.HttpError>)actionExecutedContext.Response.Content).Value;
            StringBuilder stringBuilder = new StringBuilder();
            foreach (var keyValuePair in messages) {
                stringBuilder.AppendLine("Message: Key - " + keyValuePair.Key + ", Value - " + keyValuePair.Value); 
            }
            Elmah.ErrorSignal.FromCurrentContext().Raise(new Exception("Web API Failed Status Code returned - " + stringBuilder.ToString()));
        }
        catch (Exception ex)
        {
            Elmah.ErrorSignal.FromCurrentContext().Raise(new Exception("Error in OnActionExecuted - " + ex.ToString()));
        }
    }
}

另外,我还覆盖了"OnActionExecuting"来验证模型状态.这允许我删除我的操作中的所有检查.

public override void OnActionExecuting(System.Web.Http.Controllers.HttpActionContext actionContext)
{
    if (actionContext.ModelState != null && !actionContext.ModelState.IsValid)
    {
        StringBuilder stringBuilder = new StringBuilder();
        foreach (var obj in actionContext.ModelState.Values)
        {
            foreach (var error in obj.Errors)
            {
                if(!string.IsNullOrEmpty(error.ErrorMessage)) {
                    stringBuilder.AppendLine("Error: " + error.ErrorMessage);
                }
            }
        }
        Elmah.ErrorSignal.FromCurrentContext().Raise(new Exception("Invalid Model State -- " + stringBuilder.ToString()));
        actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.BadRequest, actionContext.ModelState);
    }
}

当然,您需要使用"config.Filters.Add"添加过滤器.

Answer 2

Web API 特殊情况 HttpResponseException 在操作中抛出并转换为 HttpResponseMessage，因此您不会看到异常过滤器被调用。

在从过滤器抛出 HttpResponseException 的情况下，情况并非如此。但是，理想情况下不需要从过滤器抛出 HttpResponseException，因为您可以通过在提供的输入上下文上设置 Response 属性来短路请求。