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WebJob and ExceptionFilterAttribute

I use ExceptionFilterAttribute for my web api application to catch different unhandled exceptions, i.e.:
public class InvalidDriverExceptionAttribute : ExceptionFilterAttribute
{
public override void OnException(HttpActionExecutedContext actionExecutedContext)
{
if (actionExecutedContext.Exception != null)
{
if (actionExecutedContext.Exception is Domain.InvalidDriverException)
{
var resp = actionExecutedContext.Request.CreateErrorResponse(HttpStatusCode.NotFound, "User is not a driver");
actionExecutedContext.Response = resp;
}
}
//base.OnException(actionExecutedContext);
}
}
but I want to have similar engine for my web job. Is it possible?

but I want to have similar engine for my web job. Is it possible?
Yes. But because web jobs are continuous or schedule, there are some differences in how they are implemented. You could use ErrorTrigger to achieve your goal. An error trigger that allows you to annotate functions to be automatically called by the runtime when errors occur. It could monitor errors in web job when it is executed.My Demo result like this:filter null exception. For more details, you could refer to this article.
When developing jobs with Azure WebJob, it's a good practice to implement error monitoring in case something goes wrong when a job is executed.
The WebJobs ErrorTrigger extension, part of the Core extensions, will help us achieve that.

I have created derived class from FunctionExceptionFilterAttribute
public class ErrorHandlerAttribute : FunctionExceptionFilterAttribute
{
public override async Task OnExceptionAsync(FunctionExceptionContext exceptionContext, CancellationToken cancellationToken)
{
string body = $"ErrorHandler called. Function '{exceptionContext.FunctionName}': {exceptionContext.FunctionInstanceId} failed. ";
CombineErrorWithAllInnerExceptions(exceptionContext.Exception, ref body);
string[] emailList = System.Configuration.ConfigurationManager.AppSettings["SendErrorEmails"].Split(';');
await SendEmail.SendErrorNotificationAsync("WebJob - Common Driver Error", body);
}
private void CombineErrorWithAllInnerExceptions(Exception ex, ref string error)
{
error += $"ExceptionMessage: '{ex.Message}'.";
if (ex is Domain.BadStatusCodeException)
{
error += $"Status code: {((Domain.BadStatusCodeException)ex).StatusCode}";
}
if (ex.InnerException != null)
{
error += $"InnerEx: ";
CombineErrorWithAllInnerExceptions(ex.InnerException, ref error);
}
}
}
and then use it for method:
[NoAutomaticTrigger]
[ErrorHandler]
public async Task GetDriversAsync(TextWriter logger)
{
when exception occurs it call this code and send notification email to me

Web API 2 services - how to return an Exception message in the Status

Is it possible, in Web API 2 to directly return the Exception message in the response's Status ?
For example, if I was writing a WCF Service (rather than Webi API), I could follow this tutorial to directly return an Exception message as part of the response status:
Here, the web service doesn't return any data in the Response, and the error message gets returned directly in the Status Description.
This is exactly what I'd like my Web API services to do when an exception occurs, but I can't work out how to do it.
Most suggestions suggest using code like below, but then the error message will then always get returned in a separate response string, rather than being part of the Status.
For example, if I were to use this code:
public IHttpActionResult GetAllProducts()
{
try
{
// Let's get our service to throw an Exception
throw new Exception("Something went wrong");
return Ok(products);
}
catch (Exception ex)
{
return new System.Web.Http.Results.ResponseMessageResult(
Request.CreateErrorResponse((HttpStatusCode)500,
new HttpError("Something went wrong")));
}
}
... then it returns a generic 500 message, and the exception is returned in a JSON string.
Does anyone know how to modify a Web API function (which returns an IHttpActionResult object) to do this ?

You could register a custom global filter that will handle all Exceptions. Something like:
public class CatchAllExceptionFilterAttribute : ExceptionFilterAttribute
{
public override void OnException(HttpActionExecutedContext context)
{
context.Response = new HttpResponseMessage(HttpStatusCode.InternalServerError)
{
Content = new StringContent(context.Exception.Message)
};
}
}
You will need to register it in WebApiConfig.cs, with:
config.Filters.Add(new CatchAllExceptionFilterAttribute());
This filter will be hit everytime there is an unhandled exception in the system and set the http response to the exception message. You could also check the different types of exception and alter your response accordingly, for example:
public override void OnException(HttpActionExecutedContext context)
{
if(context.Exception is NotImplementedException)
{
context.Response = new HttpResponseMessage(HttpStatusCode.NotImplemented)
{
Content = new StringContent("Method not implemented.")
};
}
else
{
context.Response = new HttpResponseMessage(HttpStatusCode.InternalServerError)
{
Content = new StringContent(context.Exception.Message)
};
}
}

https://www.asp.net/web-api/overview/error-handling/web-api-global-error-handling
Please refer above link, it will help you!

Await Tasks in Test Setup Code in xUnit.net?

The exact situation is I'm doing E2E tests with Protractor.NET (.NET port of AngularJS's Protractor E2E framework) and I would like to make some web requests (and the API -- System.Net.Http.HttpClient -- has all Async/Task methods) to Arrange my test before I Act/Assert, only I need to do this same Arrange-ing for several tests.
I'm using xUnit.net as my test runner they use an interface (IUseFixture<T>) for per-fixture setup code. It would be nice if there was a IAsyncUseFixture<T> that had a Task SetFixtureAsync(T t); or something. I don't think such a thing exists. Additionally I don't think constructors can use await either, and constructors are the only other way to execute the same block of code per-test in xUnit.net.
What are my options? .Result? Isn't that bad practice (deadlock)?

xUnit has an IAsyncLifetime interface for async setup/teardown. The methods you need to implement are Task InitializeAsync() and Task DisposeAsync().
InitializeAsync is called immediately after the class has been created, before it is used.
DisposeAsync is called just before IDisposable.Dispose if the class also implements IDisposable.
e.g.
public class MyTestFixture : IAsyncLifetime
{
private string someState;
public async Task InitializeAsync()
{
await Task.Run(() => someState = "Hello");
}
public Task DisposeAsync()
{
return Task.CompletedTask;
}
[Fact]
public void TestFoo()
{
Assert.Equal("Hello", someState);
}
}

I would use AsyncLazy
http://blog.stephencleary.com/2012/08/asynchronous-lazy-initialization.html
In my case I want to run some integration tests against a self hosted web api.
public class BaseTest()
{
private const string baseUrl = "http://mywebsite.web:9999";
private static readonly AsyncLazy<HttpSelfHostServer> server = new AsyncLazy<HttpSelfHostServer>(async () =>
{
try
{
Log.Information("Starting web server");
var config = new HttpSelfHostConfiguration(baseUrl);
new Startup()
.Using(config)
.Add.AttributeRoutes()
.Add.DefaultRoutes()
.Remove.XmlFormatter()
.Serilog()
.Autofac()
.EnsureInitialized();
var server = new HttpSelfHostServer(config);
await server.OpenAsync();
Log.Information("Web server started: {0}", baseUrl);
return server;
}
catch (Exception e)
{
Log.Error(e, "Unable to start web server");
throw;
}
});
public BaseTest()
{
server.Start()
}
}

Signalr connects but doesn't push a message

I've been working on implementing signalr as part of a wcf service to talk to a .net client. Apart form a connection message all communication is one way passing a dynamic payload to the client side.
I've managed to set it up so that the client will connect to the service and pass a connection message but I can't get the pushing of a message from the service to the client.
Sorry if I've missed this answered else where but I've been unable to find a reason for this failing as it seems to follow the "how to's"
Any help would be much appreciated and thank you in advance
Server side:
WCF external call
public class MessageService : IMessageService
{
public string PushAlerts()
{
var payLoad = new PayLoad
{
MethodName = "alerts"
};
IHubContext connectionHub = GlobalHost.ConnectionManager.GetHubContext<PushConnection>();
connectionHub.Clients.All.Notify(payLoad);
}
}
My Hub
[HubName("PushHub")]
public class PushHub : Hub
{
public override Task OnConnected()
{
var connectionMessage = Context.QueryString["CONNECTION MESSAGE"];
if (connectionMessage != null)
{
Debug.WriteLine("connectionMessage");
}
return base.OnConnected();
}
}
ClientSide:
var querystringData = new Dictionary<string, string>{};
querystringData.Add("CONNECTION MESSAGE", "foo Connection");
var hubConnection = new HubConnection("http://localhost:60479/", querystringData); //Running local till working
hubConnection.TraceLevel = TraceLevels.All;
hubConnection.TraceWriter = Console.Out;
IHubProxy clientHubProxy = hubConnection.CreateHubProxy("PushHub");
clientHubProxy.On("Notify", payLoad =>
SynchronizationContext.Current.Post(delegate
{
ResponseMethod(payLoad);
}, null)
);
await hubConnection.Start();
I've missed out payload but that only holds a string value at present. I've also setup a pipemodule for logging perposes.
Thanks Again

Ok so I resolved this problem in two ways firstly I moved the call to the client inside the hub its self, which I then called from a method in my wcf service.
[HubName("PushHub")]
public class PushHub : Hub
{
IHubContext connectionHub = GlobalHost.ConnectionManager.GetHubContext<PushConnection>();
public void Send(Payload payload)
{
connectionHub.Clients.All.Notify(payLoad);
}
}
Secondly the client code for the method was all wrong. In the end this worked:
clientHubProxy.On("Notify", (payLoad) => { dostuff };
Took a lot of fiddling but hope my answer helps others.

Customizing SignalR's error messages

I use the SignalR 1.0.
When exception occurs on the server, the client gets a message like this
{"I":"0","E":"Exception of type 'System.Exception' was thrown.","T":" at METHODNAME in d:\PATH\TO\HUB.cs:line 227\r\n at METHODNAME in d:\PATH\TO\HUB.cs:line 51"}
But I want to make it more user-friendly. How to I can do it?
I have read a suggestion to put all server methods into try-catch block. But I think that it is not a true-way.
I traced the Exception and found that the Exception was catched in the Microsoft.AspNet.SignalR.Hubs.HubDispatcher.Incoming method. But it is internal static method which I cannot customize.
In the ideal case I want to get ability to convert an exception to a valid response.

You can use a HubPipelineModule.
For example:
using System;
using System.Threading.Tasks;
using Microsoft.AspNet.SignalR.Hubs;
public class MyHubPipelineModule : HubPipelineModule
{
protected override Func<IHubIncomingInvokerContext, Task<object>> BuildIncoming(Func<IHubIncomingInvokerContext, Task<object>> invoke)
{
return async context =>
{
try
{
// This is responsible for invoking every server-side Hub method in your SignalR app.
return await invoke(context);
}
catch (Exception e)
{
// If a Hub method throws, have it return the error message instead.
return e.Message;
}
};
}
}
Then in your Global.asax.cs:
protected void Application_Start()
{
GlobalHost.HubPipeline.AddModule(new MyHubPipelineModule());
//...
RouteTable.Routes.MapHubs();
}