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.NetCore 2.x on using {*catchAll} routing URL.Action always returns null

I am using this route to map all routes which were not found:
routes.MapRoute(
name: "NotFound",
template: "{*url}",
defaults: new { controller = "Home", action = "NotFound" }
);
The problem I encountered is that #Url.Action() always returns null on this route.
Could someone explain why is this happening and what could be alternatives to this?

you have to add the below code before the app.UseMvc(...[Routing] ...), make sure you use it in the right order because the order really matters, the pipeline in asp.net core is in reverse order meaning that if you add A before B then B will be called before A, you can read more here: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/middleware/?view=aspnetcore-2.1#order
app.UseStatusCodePagesWithReExecute("/error/{0}");
and in the controllers consider an ErrorController which contains different error codes here we just consider 404 and 500 errors in ErrorController, we must have the corresponding views for each error code (404, 500, Unknown)
public class ErrorController : ControllerBase
{
[Route("error/{code:int}")]
public ActionResult Error(int code)
{
switch (code)
{
case 404: return View("404");
case 500: return View("500");
default: return View("Unknown");
}
}
}
for more concise description please check Microsoft documentation here: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/error-handling?view=aspnetcore-2.1

I suppose you call #Url.Action() either with route parameters (e.g. controller = "Home", action = "NotFound") or with route name - that makes no difference - to generate a URL to your not found page. Well, you said the URL can be any thing which effects in in-bound routing and it's just fine. But, when you are trying to generate URLs from a route (out-bound routing), the route hasn't any template to generate a URL. In route's perspective, it can be any URL. So, null is any URL too. So, the null will be returned.

After playing around, I found a "cheat" way to do it and it kinda works. If I get NotFound page then I redirect back to the same page if Url.Action() == null
if(this._urlService.Action() == null) //same urlHelper action, only has default Home page values passed into method
{
var query = string.Empty;
if(Request.QueryString.HasValue)
{
query = Request.QueryString.Value;
}
var path = "/Home/NotFound" + query;
path = string.Concat("/", this._userIdentity.CurrentLanguage.ToString().ToLower(), path);
return base.Redirect(path);
}
It could be because I use /{culture}/{Controller}/{Action} as my main route. Creating other test project, where my main route is default /{Controller}/{Action} has no problem at all finding the Url.Action() on NotFound page

C# URL Routing with variable parameters

I have two methods in two separate controllers that I want to access, but can't seem to figure out how the custom routes should look like and if it's possible to do it without manually writing all the routes.
What I'm trying to achieve:
baseUrl/businessOwner/identity
to map to BusinessOwnerController, Identity action
baseUrl/{employee}/identity
to map to EmployeeController, Identity action
where {employee} will be a string to which I'm matching the value in the database.
Also, I want other URLs to be able to map themselves to their default behavior, such that:
baseUrl/accountant/identity
will not match on the previous routes, but will go to the default behavior: accountant - AccountantController, Identity action.
The only way for this to work (as far as I've found) was to manually map the routes in RegisterRoutes.
I've tried doing a custom route:
routes.MapRoute(
"BusinessOwner",
"businessOwner/{action}/{id}",
new { controller = "BusinessOwner", action = "Identity", id = UrlParameter.Optional }
);
before the default route, but that doesn't really work out, as the "Multiple controller match" error still pops up.
I've also tried separating the controllers into different namespaces within the same Controllers folder and do the routing based on that, but still unsuccessful.
Any ideas?

Look at it this way: You are using the same part of the URL to hold either an employee identifier or a string constant "BusinessOwner," which acts as a magic string to invoke the BusinessOwnerController instead of the EmployeeController.
Set up your main routes to always go to the EmployeeController, and then add in a special check in the EmployeeController which will pass control to the BusinessOwnerController if the special employee ID of "BusinessOwner" is detected.
class EmployeeController : Controller
{
public ActionResult Identity(string employeeID)
{
if (employeeID == "BusinessOwner")
{
var businessOwnerController = new BusinessOwnerController();
businessOwnerController.ControllerContext = new ControllerContext(
this.ControllerContext.RequestContext,
businessOwnerController
);
return businessOwnerController.Identity();
}
else
{
//Do employee stuff
}
}
}

If Route doesn't exist -> go to other route using its default action?

So I'm having a little problem here with routing.
There are two parts to this web application:
  1. Brochure / Display Website
  2. Internal Site / Client Application
We wanted a way to release changes for the brochure without having to do a whole release of said Web application.
Visiting existing named views will take the user to a brochure page, however if it doesn't exist, it will act like they are a client and will redirect them to their company's login screen.
Global.asax:
//if view doesnt exist then url is a client and should be redirected
routes.MapRoute(
name: "Brochure",
url: "{id}",
defaults: new { controller = "brochure", action = "Brochure", id = "Index" },
namespaces: new[] { "Web.Areas.Brochure.Controllers" }
);
//This is home page
routes.MapRoute(
name: "HomeDefault",
url: "{client}/{action}",
defaults: new { controller = "home", action = "index" },
namespaces: new string[] { "Web.Controllers" }
);
Controller:
/// <summary> Check if the view exists in our brochure list </summary>
private bool ViewExists(string name) {
ViewEngineResult result = ViewEngines.Engines.FindView(ControllerContext, name, null);
return (result.View != null);
}
/// <summary> Generic action result routing for all pages.
/// If the view doesn't exist in the brochure area, then redirect to interal web
/// This way, even when we add new pages to the brochure, there is no need to re-compile & release the whole Web project. </summary>
public ActionResult Brochure(string id) {
if (ViewExists(id)) {
return View(id);
}
return RedirectToRoute("HomeDefault", new { client = id });
}
This code works fine up until we log in and go to the landing page. It seems to keep the Brochure action in the route and doesn't want to go to the subsequent controller which results in a 500 error.
e.g. 'domain/client/Brochure' when it needs to be: 'domain/client/Index'
Things tried but not worked:
Changing RedirectToRoute() to a RedirectToAction() - this results in a
finite loop of going back to the ActionResult Brochure(). So
changing controllers through that didn't work.
Create an ActionResult called Brochure() inside the 'HomeController'. It
doesn't even get hit.
Passed in namespaces for RedirectToRoute() as an attribute. I knew this would probably not work, but it was worth a try.
So the question is:
How can I get the route to act properly?

If you can restrict id to some subset of all values you can add that constraints to route (i.e. numbers only) to let default handle the rest.
routes.MapRoute(
name: "Brochure",
url: "{id}",
defaults: new { controller = "brochure", action = "Brochure", id = "Index" },
namespaces: new[] { "Web.Areas.Brochure.Controllers" }
constraints : new { category = #"\d+"}
);
If you can't statically determine restrictions - automatically redirecting in your BrochureController similar to your current code would work. The only problem with sample in the question is it hits the same route again and goes into infinite redirect loop - redirect to Url that does not match first rule:
// may need to remove defaults from second route
return RedirectToRoute("HomeDefault", new { client = id, action = "index" });
If standard constraints do not work and you must keep single segment in url - use custom constraints - implement IRouteConstraint and use it in first route. See Creating custom constraints.

There are several issues with your configuration. I can explain what is wrong with it, but I am not sure I can set you on the right track because you didn't provide the all of the URLs (at least not all of them from what I can tell).
Issues
Your Brouchure route, which has 1 optional URL segment named {id}, will match any URL that is 0 or 1 segments (such as / and /client). The fact that it matches your home page (and you have another route that is named HomeDefault that will never be given the chance to match the home page) leads me to believe this wasn't intended. You can make the {id} value required by removing the default value id = "Index".
The Brouchure route has a namespace that indicates it is probably in an Area. To properly register the area, you have to make the last line of that route ).DataTokens["area"] = "Brochure"; or alternatively put it into the /Areas/Brouchure/AreaRegistration.cs file, which will do that for you.
The only way to get to the HomeDefault route is to supply a 2 segment URL (such as /client/Index, which will take you to the Index method on the HomeController). The example URLs you have provided have 3 segments. Neither of the routes you have provided will match a URL with 3 segments, so if these URLs are not getting 404 errors they are obviously matching a route that you haven't provided in your question. In other words, you are looking for the problem in the wrong place.
If you provide your entire route configuration including all Area routes and AttributeRouting routes (including the line that registers them), as well as a complete description of what URL should go to what action method, I am sure you will get more helpful answers.
So the question is:
How can I get the route to act properly?
Unknown. Until you describe what properly is.
Related: Why map special routes first before common routes in asp.net mvc?

Two ways I could have solved this issue:
Way 1
I reviewed the redirect and just passed in an action in order to get a route that has 2 segments in the url. i.e. client/Index. The Index action now handles logins - going past a custom controller.
public class HomeController : CustomController
public ActionResult Brochure(string id, string action) {
if (ViewExists(id)) {
return View(id);
}
return RedirectToAction("Index", "Home", new { client = id, action = "Index" });
}
Way 2
(from #Alexei_Levenkov)
Create a custom Route constraint so the route will be ignored if the view cannot be found.
namespace Web.Contraints {
public class BrochureConstraint : IRouteConstraint {
public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection) {
//Create our 'fake' controllerContext as we cannot access ControllerContext here
HttpContextWrapper context = new HttpContextWrapper(HttpContext.Current);
RouteData routeData = new RouteData();
routeData.Values.Add("controller", "brochure");
ControllerContext controllerContext = new ControllerContext(new RequestContext(context, routeData), new BrochureController());
//Check if our view exists in the folder -> if so the route is valid - return true
ViewEngineResult result = ViewEngines.Engines.FindView(controllerContext, "~/Areas/Brochure/Views/Brochure/" + values["id"] + ".cshtml", null);
return result.View != null;
}
}
}
namespace Web {
public class MvcApplication : System.Web.HttpApplication {
//If view doesnt exist then url is a client so use the 'HomeDefault' route below
routes.MapRoute(
name: "Brochure",
url: "{id}",
defaults: new { controller = "brochure", action = "Brochure", id = "Index" },
namespaces: new[] { "Web.Areas.Brochure.Controllers" },
constraints: new { isBrochure = new BrochureConstraint() }
);
//This is home page for client
routes.MapRoute(
name: "HomeDefault",
url: "{client}/{action}",
defaults: new { controller = "home", action = "index" },
namespaces: new string[] { "Web.Controllers" }
);
}
}
I hope this helps someone else out there.

ASP.NET MVC multiple url's pointing to the same action

How do i map multiple url's to the same action in asp.net mvc
I have:
string url1 = "Help/Me";
string url2 = "Help/Me/Now";
string url3 = "Help/Polemus";
string url1 = "Help/Polemus/Tomorow";
In my global.asax.cs file i want to map all those url to the following action:
public class PageController : Controller
{
[HttpGet]
public ActionResult Index()
{
return View();
}
}

Now in MVC 5 this can be achieved by using Route Attribute.
[Route("Help/Me")]
[Route("Help/Me/Now")]
[Route("Help/Polemus")]
[Route("Help/Polemus/Tomorow")]
public ActionResult Index()
{
return View();
}

Add the following line to your routing table:
routes.MapRoute("RouteName", "Help/{Thing}/{OtherThing}", new { controller = "Page" });
EDIT:
foreach(string url in urls)
routes.MapRoute("RouteName-" + url, url, new { controller = "Page", action = "Index" });

In my case I was looking to simply combine two 'hardcoded' routes into one and stumbled upon this post. I wanted to clean out my RouteConfig.cs a little - because it had so many similar routes.
I ended up using some simple 'or' logic in a regular expression and basically changed:
routes.MapRoute(
"UniqueHomePage",
"Default",
new { controller = "Redirector", action = "RedirectToRoot" }
);
routes.MapRoute(
"UniqueHomePage2",
"Home",
new { controller = "Redirector", action = "RedirectToRoot" }
);
Into a single route:
routes.MapRoute(
"UniqueHomePageGeneric",
"{url}",
new { controller = "Redirector", action = "RedirectToRoot" },
new { url = "Home|Default" }
);
Note for the SEO-savy or -interested: The reason for pointing multiple URL's to one and the same action, is to then redirect them to one and the same page again. In this case the homepage. So the idea is to prevent duplicate content issues. When you use this method for pointing for NON redirecting actions, but actions that show their own views, then you might be CAUSING duplicate content issues :P.

You can just add the routes into your route table as you need them, same as any other route. Just give them unique names, hard coded URL and point them to the same controller / action. It will work fine.
If you use pattern matching instead of hard coded URLs just make sure you get all your routes in the right order so the correct one is selected from the list. So /Help/Me should appear before /Help/{Page} if the hard coded route goes to a different page to the pattern matched one. If you put /help/{page} in the route tabel 1st this will match to /help/me and your hard coded named action for that route would never fire.
On a side note, if this is a public facing site and SEO is important please be careful if you have multiple URLs returning the same data, it will be flagged as duplicate. If this is the case, then use the Canonical tag, this gives all the page rank from all the URLS that go to that single page to the one you name and removes the duplicate content issue for you.

ASP.NET MVC Beta Routes, Controller Actions, Parameters and ActionsLinks...putting it all together

I'm having some trouble with ASP.NET MVC Beta, and the idea of making routes, controller actions, parameters on those controller actions and Html.ActionLinks all work together. I have an application that I'm working on where I have a model object called a Plot, and a corresponding PlotController. When a user creates a new Plot object, a URL friendly name gets generated (i.e.). I would then like to generate a "List" of the Plots that belong to the user, each of which would be a link that would navigate the user to a view of the details of that Plot. I want the URL for that link to look something like this: http://myapp.com/plot/my-plot-name. I've attempted to make that happen with the code below, but it doesn't seem to be working, and I can't seem to find any good samples that show how to make all of this work together.
My Route definition:
routes.MapRoute( "PlotByName", "plot/{name}", new { controller = "Plot", action = "ViewDetails" } );
My ControllerAction:
[Authorize]
public ActionResult ViewDetails( string plotName )
{
ViewData["SelectedPlot"] = from p in CurrentUser.Plots where p.UrlFriendlyName == plotName select p;
return View();
}
As for the ActionLink, I'm not really sure what that would look like to generate the appropriate URL.
Any assistance would be greatly appreciated.

The answer is pretty simple: You have to supply enough values in your "ActionLink" that will fulfill your Route. Example:
<%= Html.ActionLink("Click Here", "ViewDetails", "Plot", new { name="my-plot-name" }, null)%>
If you leave out the "name=" part of the ActionLink method, then the RouteEngine won't see this link as being good enough to "match"... so then it would go to the default route.
This code above will make the URL look the way you want it.

How about this code-fix? (Note the name = null, appened to the end of the 4th line....)
routes.MapRoute(
"PlotByName",
"plot/{name}",
new { controller = "Plot", action = "ViewDetails", name = null }
);
and this should be renamed.. (notice plotName is renamed to name)
public ActionResult ViewDetails(string name ) { ... }
does that help?