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Is there a way to generate Urls with WebAPI?

POST EDITED BELOW
We can't figure out why UrlHelper is returning null strings when used from the WebApi controller's context.
We've done the neccesary debugging but we can't find out why this happens, the RouteData has the routes in it but it doesn't seem to be working.
For the most part, we use a RenderViewToString function, which loads views that consist of calls to Url.RouteUrl(routeName).
Something that's been tried is creating a custom UrlHelper (but to no avail) and debugging with either UrlHelper's (MVC / HTTP).
Attribute routing is used everywhere with route names.
Example usage code:
public class WebApiController : BaseApiController
{
[HttpPost]
[ResponseType(typeof(string))]
[Route("cart/get/checkout", Name = "api.cart.get.checkout")]
public IHttpActionResult GetCheckOutShoppingCart([FromBody] string data)
{
return Ok(RenderViewToString("CartController", "_CheckOutCartPartial", new ShoppingCartModel(Auth.IsAuthenticated ? Auth.GetCustomer().DefaultShippingInfo.CountryId : 148)
{
AddInsurance = false,
InsuredShipping = insuredShipping,
CurrentDeliveryMethodId = deliveryMethodId,
CurrentPaymentMethodId = paymentMethodId
}));
}
}
BaseApiController class:
public class BaseApiController : ApiController
{
public static string RenderViewToString(string controllerName, string viewName)
{
return RenderViewToString(controllerName, viewName, new Dictionary<string, object>());
}
public static string RenderViewToString(string controllerName, string viewName, object model)
{
using (var writer = new StringWriter())
{
var routeData = new RouteData();
routeData.Values.Add("controller", controllerName);
var fakeControllerContext =
new ControllerContext(
new HttpContextWrapper(new HttpContext(new HttpRequest(null, "http://google.com", null),
new HttpResponse(null))), routeData, new FakeController());
var razorViewEngine = new RazorViewEngine();
var razorViewResult = razorViewEngine.FindView(fakeControllerContext, viewName, "", false);
var viewContext = new ViewContext(fakeControllerContext, razorViewResult.View,
new ViewDataDictionary(model), new TempDataDictionary(), writer);
razorViewResult.View.Render(viewContext, writer);
return writer.ToString();
}
}
public static string RenderViewToString(string controllerName, string viewName, Dictionary<string, Object> data)
{
using (var writer = new StringWriter())
{
var viewData = new ViewDataDictionary();
foreach (var kv in data)
{
viewData[kv.Key] = kv.Value;
}
var routeData = new RouteData();
routeData.Values.Add("controller", controllerName);
var fakeControllerContext =
new ControllerContext(
new HttpContextWrapper(new HttpContext(new HttpRequest(null, "http://google.com", null),
new HttpResponse(null))), routeData, new FakeController());
var razorViewEngine = new RazorViewEngine();
var razorViewResult = razorViewEngine.FindView(fakeControllerContext, viewName, "", false);
var viewContext = new ViewContext(fakeControllerContext, razorViewResult.View, viewData,
new TempDataDictionary(), writer);
razorViewResult.View.Render(viewContext, writer);
return writer.ToString();
}
}
private class FakeController : ControllerBase
{
protected override void ExecuteCore()
{
}
}
}
EDIT
We've put together a class that should in theory work, but it doesn't.
The RouteData has both the MVC and API routes in the collection.
public static class Url
{
public static bool IsWebApiRequest()
{
return
HttpContext.Current.Request.RequestContext.HttpContext.CurrentHandler is
System.Web.Http.WebHost.HttpControllerHandler;
}
public static string RouteUrl(string routeName, object routeValues = null)
{
var url = String.Empty;
try
{
if (IsWebApiRequest())
{
var helper = new System.Web.Http.Routing.UrlHelper();
url = helper.Link(routeName, routeValues);
}
else
{
var helper = new System.Web.Mvc.UrlHelper();
url = helper.RouteUrl(routeName, routeValues);
}
return url;
}
catch
{
return url;
}
}
public static string HttpRouteUrl(string routeName, object routeValues = null)
{
var url = String.Empty;
try
{
if (IsWebApiRequest())
{
var helper = new System.Web.Http.Routing.UrlHelper();
url = helper.Link(routeName, routeValues);
}
else
{
var helper = new System.Web.Mvc.UrlHelper();
url = helper.HttpRouteUrl(routeName, routeValues);
}
return url;
}
catch
{
return url;
}
}
}

This issue has been resolved by building a custom UrlHelper class, which looks into the RouteTable and then returns the url with the patterns replaced.
public static class Link
{
public static string RouteUrl(string routeName, object routeValues = null)
{
var url = String.Empty;
try
{
var route = (Route)RouteTable.Routes[routeName];
if (route == null)
return url;
url = "~/".AbsoluteUrl() + route.Url;
url = url.Replace("{culture}", System.Threading.Thread.CurrentThread.CurrentCulture.TwoLetterISOLanguageName.ToLower());
if (routeValues == null)
return url;
var values = routeValues.GetType().GetProperties();
Array.ForEach(values, pi => url = Regex.Replace(url, "{" + pi.Name + "}", pi.GetValue(routeValues, null).ToString()));
return url;
}
catch
{
var newUrl = RouteUrl("403");
if(newUrl == String.Empty)
throw;
return newUrl;
}
}
public static string HttpRouteUrl(string routeName, object routeValues = null)
{
return RouteUrl(routeName, routeValues);
}
}

Try Uri.Link(routeName, object)
var uri = Url.Link("api.cart.get.checkout", new { id = 1 });
This will inject the given object's properties into the route if the property name matches a route parameter.

WebApi is not MVC. Even though it looks very similar, it's a completely different system.
UrlHelper (which is MVC) will be looking at the MVC route table, and ignore any WebApi routes.
Try creating the route the hard way, essentially hard-coding the controller and action names into the views. :-(

OK, based on your comment, it seems that you're trying to call your Url.RouteUrl(string routeName, object routeValues = null) or Url.HttpRouteUrl(string routeName, object routeValues = null) from your MVC layout.cshtml file.
If that's the case, the Url.IsWebApiRequest() would return false because the layout.cshtml file is only processed as part of handling MVC request and not WebAPI. That will cause the url generation methods to use MVC route collection instead of the WebAPI collection.
Change your Url class so that RouteUrl always builds WebAPI url and HttpRouteUrl only builds MVC url then in your layout file use proper method based on which kind of url you need in the particular context.
public static class Url
{
public static bool IsWebApiRequest()
{
return
HttpContext.Current.Request.RequestContext.HttpContext.CurrentHandler is
System.Web.Http.WebHost.HttpControllerHandler;
}
public static string RouteUrl(string routeName, object routeValues = null)
{
var url = String.Empty;
try
{
var helper = new System.Web.Http.Routing.UrlHelper();
return helper.Link(routeName, routeValues);
}
catch
{
return url;
}
}
public static string HttpRouteUrl(string routeName, object routeValues = null)
{
var url = String.Empty;
try
{
var helper = new System.Web.Mvc.UrlHelper();
return helper.HttpRouteUrl(routeName, routeValues);
}
catch
{
return url;
}
}
}

Retrieve Instance of ActionExecutingContext

I would like to retrieve the instance of ActionExecutingContext inside of
public ActionResult Contact2(string one, string two)
and not in the class albumAttribute.
Is it possible to do it?
Thanks!
[HttpPost]
[album]
public ActionResult Contact2(string one, string two)
{
ViewBag.Message = "Your contact page.";
var ss = Response.Status;
var genres = new List<Genre>
{
new Genre { Name = "Disco"},
new Genre { Name = "Jazz"},
new Genre { Name = "Rock"}
};
//return View(genres);
//return View("contact2", genres);
return View("contact22", genres);
}
public class albumAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
HttpRequestBase req = filterContext.HttpContext.Request;
HttpResponseBase res = filterContext.HttpContext.Response;
UriBuilder uriBuilder = new UriBuilder("http://" + req.Url.Authority + req.Url.LocalPath);
NameValueCollection query = HttpUtility.ParseQueryString(uriBuilder.Query);
query.Add("album", "first");
uriBuilder.Query = query.ToString();
string url = req.Url.AbsolutePath.ToString();
res.Redirect(uriBuilder.Uri.OriginalString);
base.OnActionExecuting(filterContext);
/*
UriBuilder uriBuilder = new UriBuilder("http://" + req.Url.Authority + "/Home/About");
res.Redirect(uriBuilder.Uri.OriginalString);
base.OnActionExecuting(filterContext);
*/
}
}

Based on your comments:
Action filters execute prior to Actions so inside an Action you won't be able to use base.OnActionExecuting(filterContext).
Other than that all the code that's attached in the image could be executed without ActionExecutingContext object, just add it to your Action and for getting a Request and Response objects use Response and Request controller properties.
You can also use
return this.Redirect(yourUrl);
instead of res.Redirect(...)
[HttpPost]
[album]
public ActionResult Contact2(string one, string two)
{
var req = this.Request;
var res = this.Response;
UriBuilder uriBuilder = new UriBuilder("http://" + req.Url.Authority + req.Url.LocalPath);
NameValueCollection query = HttpUtility.ParseQueryString(uriBuilder.Query);
query.Add("album", "first");
uriBuilder.Query = query.ToString();
string url = req.Url.AbsolutePath.ToString();
return this.Redirect(uriBuilder.Uri.OriginalString);
}

MVC HttpRequestValidationException exception

I am coding a MVC 5 internet application and have a question in regards to the HttpRequestValidationException exception.
My previous code in my controller is as follows:
protected override void OnException(ExceptionContext filterContext)
{
// Make use of the exception later
this.Session["ErrorException"] = filterContext.Exception;
if (filterContext.Exception is HttpRequestValidationException)
{
TempData["UITitle"] = "Validation";
TempData["UIHeading"] = customErrorType;
TempData["UIMessage"] = filterContext.Exception.Message;
TempData["UIException"] = filterContext.Exception;
filterContext.ExceptionHandled = true;
}
else
{
TempData["UITitle"] = "Error";
TempData["UIHeading"] = customErrorType;
TempData["UIMessage"] = filterContext.Exception.Message;
TempData["UIException"] = filterContext.Exception;
}
filterContext.Result = this.RedirectToAction("Index", "Error");
base.OnException(filterContext);
}
If an exception occurred, then the Index view in the Error controller displayed this error.
I have now written the following global filter:
public class ExceptionFilterDisplayErrorView : IExceptionFilter
{
public virtual void OnException(ExceptionContext filterContext)
{
filterContext.ExceptionHandled = true;
RouteValueDictionary routeValueDictionary = new RouteValueDictionary();
routeValueDictionary.Add("controller", "Error");
routeValueDictionary.Add("action", "Index");
filterContext.Controller.TempData.Clear();
filterContext.Controller.TempData.Add("UITitle", "Error");
filterContext.Controller.TempData.Add("UIHeading", "Error");
filterContext.Controller.TempData.Add("UIMessage", filterContext.Exception.Message);
filterContext.Controller.TempData.Add("UIException", filterContext.Exception);
RedirectToRouteResult redirectToRouteResult = new RedirectToRouteResult(routeValueDictionary);
filterContext.Result = redirectToRouteResult;
}
}
The above filter works the same as the previous OnException function, except now, if a HttpRequestValidationException exception occurs, the default stack trace page is shown, rather than the Error controller view.
Is it possible to display a custom error view for HttpRequestValidationException exceptions in an exception filter?

Something like this works for me.
public class CustomExceptionAttribute : FilterAttribute, IExceptionFilter
{
public void OnException(ExceptionContext filterContext)
{
if (!filterContext.ExceptionHandled)
{
int val = (int)(((Exception)filterContext.Exception).ActualValue);
filterContext.Result = new ViewResult
{
ViewName = "CustomError",
ViewData = new ViewDataDictionary<int>(val)
};
filterContext.ExceptionHandled = true;
}
}
}
** EDIT ***
public class HttpRequestValidationExceptionAttribute : FilterAttribute, IExceptionFilter
{
public void OnException(ExceptionContext filterContext)
{
if (!filterContext.ExceptionHandled && filterContext.Exception is HttpRequestValidationException)
{
IDictionary val = filterContext.Exception.Data;
filterContext.Result = new ViewResult
{
ViewName = "RangeError",
ViewData = new ViewDataDictionary<IDictionary>(val)
};
filterContext.ExceptionHandled = true;
}
}
}

Asp.Net Mvc Display exception in View from tempdata

I am handling error in Base controller. I need to display the error stored in tempdata, Exception type in a razor view. How can I do that?
Base Controller code
protected override void OnException(ExceptionContext filterContext)
{
// if (filterContext.ExceptionHandled)
// return;
//Let the request know what went wrong
filterContext.Controller.TempData["Exception"] = filterContext.Exception.Message;
//redirect to error handler
filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary(
new { controller = "Error", action = "Index" }));
// Stop any other exception handlers from running
filterContext.ExceptionHandled = true;
// CLear out anything already in the response
filterContext.HttpContext.Response.Clear();
}
Razor View Code
<div>
This is the error Description
#Html.Raw(Html.Encode(TempData["Exception"]))
</div>

Try to make common exception attribute handling and register it as global filters. Like,
Common Exception Handling attribute :
/// <summary>
/// This action filter will handle the errors which has http response code 500.
/// As Ajax is not handling this error.
/// </summary>
[AttributeUsage(AttributeTargets.Class)]
public sealed class HandleErrorAttribute : FilterAttribute, IExceptionFilter
{
private Type exceptionType = typeof(Exception);
private const string DefaultView = "Error";
private const string DefaultAjaxView = "_Error";
public Type ExceptionType
{
get
{
return this.exceptionType;
}
set
{
if (value == null)
{
throw new ArgumentNullException("value");
}
this.exceptionType = value;
}
}
public string View { get; set; }
public string Master { get; set; }
public void OnException(ExceptionContext filterContext)
{
if (filterContext == null)
{
throw new ArgumentNullException("filterContext");
}
if (!filterContext.IsChildAction && (!filterContext.ExceptionHandled && filterContext.HttpContext.IsCustomErrorEnabled))
{
Exception innerException = filterContext.Exception;
// adding the internal server error (500 status http code)
if ((new HttpException(null, innerException).GetHttpCode() == 500) && this.ExceptionType.IsInstanceOfType(innerException))
{
var controllerName = (string)filterContext.RouteData.Values["controller"];
var actionName = (string)filterContext.RouteData.Values["action"];
var model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);
// checking for Ajax request
if (filterContext.HttpContext.Request.IsAjaxRequest())
{
var result = new PartialViewResult
{
ViewName = string.IsNullOrEmpty(this.View) ? DefaultAjaxView : this.View,
ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
TempData = filterContext.Controller.TempData
};
filterContext.Result = result;
}
else
{
var result = this.CreateActionResult(filterContext, model);
filterContext.Result = result;
}
filterContext.ExceptionHandled = true;
}
}
}
private ActionResult CreateActionResult(ExceptionContext filterContext, HandleErrorInfo model)
{
var result = new ViewResult
{
ViewName = string.IsNullOrEmpty(this.View) ? DefaultView : this.View,
MasterName = this.Master,
ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
TempData = filterContext.Controller.TempData,
};
result.TempData["Exception"] = filterContext.Exception;
return result;
}
}
And Error/_Error view
#model HandleErrorInfo
<div>
This is the error Description
#TempData["Exception"]
</div>

I agree that you should never expose an exception to your view but if you really need to, try using a custom attribute.
public class CustomExceptionAttribute : System.Web.Mvc.HandleErrorAttribute
{
public override void OnException(System.Web.Mvc.ExceptionContext filterContext)
{
if (!filterContext.ExceptionHandled)
{
filterContext.Controller.TempData.Add("Exception", filterContext.Exception);
filterContext.ExceptionHandled = true;
}
}
}
public class MyController : System.Web.Mvc.Controller
{
[CustomException]
public ActionResult Test()
{
throw new InvalidOperationException();
}
}
If you override the OnException method in the base controller, then every action will get an Exception object placed in temp data. This maybe the desired behavior but with an attribute you can selectively enable this feature.

I would strongly suggest not to show any detailed exception information in any public facing application as this could end up as a security issue. However, if this is an intranet application with controlled access or if you REALLY want to show the exception details, create a DisplayTemplate and use it as follows:
<div>
Exception Details
#Html.Display(TempData["Exception"])
</div>

ASP.net MVC - Custom HandleError Filter - Specify View based on Exception Type

I am inheriting the HandleErrorAttribute in my MVC application so I can log the error:
public class HandleAndLogErrorAttribute : HandleErrorAttribute
{
public override void OnException(ExceptionContext filterContext)
{
base.OnException(filterContext);
if( filterContext.Exception != null )
{
// log here
}
}
}
I'm adding this as a global filter:
public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
filters.Add(new HandleAndLogErrorAttribute());
}
Is it possible to specify a custom view for specific exception types as well? For example:
if( filterContext.Exception is DivideByZeroException )
{
// how do i specify that the view should be DivideByZero?
}

Create a new filter which inherits HandleErrorAttribute (or implements IExceptionFilter directly)
Register it in global.asax (by replacing filters.Add(new HandleError());):
Here is a filter that I've created that tries to find a view per specific HTTP status code:
public class MyErrorHandler : FilterAttribute, IExceptionFilter
{
public void OnException(ExceptionContext filterContext)
{
if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
return;
var statusCode = (int) HttpStatusCode.InternalServerError;
if (filterContext.Exception is HttpException)
{
statusCode = filterContext.Exception.As<HttpException>().GetHttpCode();
}
else if (filterContext.Exception is UnauthorizedAccessException)
{
//to prevent login prompt in IIS
// which will appear when returning 401.
statusCode = (int)HttpStatusCode.Forbidden;
}
_logger.Error("Uncaught exception", filterContext.Exception);
var result = CreateActionResult(filterContext, statusCode);
filterContext.Result = result;
// Prepare the response code.
filterContext.ExceptionHandled = true;
filterContext.HttpContext.Response.Clear();
filterContext.HttpContext.Response.StatusCode = statusCode;
filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
}
protected virtual ActionResult CreateActionResult(ExceptionContext filterContext, int statusCode)
{
var ctx = new ControllerContext(filterContext.RequestContext, filterContext.Controller);
var statusCodeName = ((HttpStatusCode) statusCode).ToString();
var viewName = SelectFirstView(ctx,
"~/Views/Error/{0}.cshtml".FormatWith(statusCodeName),
"~/Views/Error/General.cshtml",
statusCodeName,
"Error");
var controllerName = (string) filterContext.RouteData.Values["controller"];
var actionName = (string) filterContext.RouteData.Values["action"];
var model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);
var result = new ViewResult
{
ViewName = viewName,
ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
};
result.ViewBag.StatusCode = statusCode;
return result;
}
protected string SelectFirstView(ControllerContext ctx, params string[] viewNames)
{
return viewNames.First(view => ViewExists(ctx, view));
}
protected bool ViewExists(ControllerContext ctx, string name)
{
var result = ViewEngines.Engines.FindView(ctx, name, null);
return result.View != null;
}
}