Retrieving Route Data from Virtual Path in MVC Router

[Eilon]

From @knyzorg on Monday, 13 August 2018 20:01:26

I am working on an .NET Core MVC application which requires alternative controller/action names to be allowed. To accomplish this, I am using my own Router on a MapRoute:

app.UseMvc(routes =>
        {
            routes.Routes.Add(new CustomRouter(routes.DefaultHandler));
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });

My custom router observes the requested controller and action, and based on it places a new value into the RouteData in the request:

public async Task RouteAsync(RouteContext context)
{
   [...]
   if (requestedAction == "fakeAction")
    context.RouteData.Values["action"] = "realAction";

However, to determine the value of the requestedAction, I am basically taking the requested path, splitting it and getting the value of it that way. This seems suboptimal.

What I would like to do would look something like this:

var rr = new RouteBuilder(app);
var myRoute = rr.MapRoute(...).Build();
var myRouteData = myRoute.GetRouteData(context);
myRouteData["action"] == "fakeAction";

Another solution to this problem which I would very much enjoy is if I could do the following:

   app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "something",
                template: "{controller=Home}/{action=Index}/{id?}");
            routes.Routes.Add(new CustomRouter(routes.DefaultHandler));
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });

But NOT have my something route actually route anything and only serve as a way to define the RouteData for my CustomRouter.

Is either of these possible? I do not like the idea us uncleanly implementing existing functionality as it is a both a code smell and a potential maintenance difficulty in the future.

Copied from original issue: dotnet/aspnetcore#3427

[mkArtakMSFT]

Thanks for contacting us, @knyzorg.
@rynowak, what are your thoughts regarding this?

[rynowak]

@knyzorg - at a high level what are you trying to accomplish?

[vezaynk]

Really I just want to be able to have synonyms for controller and action names. I want /foo/bar to trigger the same code paths as /oof/rab if I so desire.

The reason for this is URL internationalization, I want to have urls look like en/hello/world and fr/salut/monde which map to the same page. I would leave MVC behind completely in favor of writing my own convention, but the convenience of having url templates and generating anchor tags automatically is too good to pass up.

Another need which I have, is for it not to break virtual paths (IIS).

Ideally, none of the synonyms would be hard-coded, I would rather be able to have some logic deciding what action (if any) the requested one is synonymous to during a request.

Anything like this possible?

[rynowak]

Thanks, that's what I thought you might be asking 😀

to trigger the same code paths as /oof/rab if I so desire

Should this include views? If you have views, will this include different .cshtml files for each locale?

How do you want/expect link generation to work? Do you want something like:

Url.Action("World", "Hello", new { locale = "fr" }) -> /fr/salut/monde

OR

Url.Action("Monde", "Salut") -> /fre/salut/monde

I'm asking for clarification because there are a few difference schemes for how to implement something like this. The major pivot is whether you want to introduce another route value that represents the locale, or whether you want to localize the route values themselves.

[vezaynk]

If the link generation could work by allowing me to specify the local myself, that would really be ideal if possible. So the first variant please.

Url.Action is basically the same thing as the <a> helper tag, right?

[rynowak]

Url.Action is basically the same thing as the helper tag, right?

Yes, exactly.

[rynowak]

Give me a bit, I'll whip up a sample of this.

[rynowak]

@knyzorg - reading through your question again, I'm wondering if I forgot to point out something obvious.

You can change routes.DefaultHandler so that it points to your custom route. Then you'll be called with the route values on the way in, and when links are being generated.

Inside RouteAsync translate the values from the locale to whatever language you're writing code in, and then do the reverse in GetVirtualPath

routes.DefaultHandler = new TranslationRoute(routes.DefaultHandler);

Is this what you're looking for?

---

Another option that I've helped people used in the past is to use IActionModelConvention to 'multiply' actions - you can do all of the translations at startup time, and we'll handle all of the processing for you.

This won't be useful to you if you need to loop up the strings when each request is processed. Let me know if you're interested in this instead and I'll put together a sample.

[vezaynk]

How would TranslationRoute be implemented?

[rynowak]

Inside RouteAsync translate the values from the locale to whatever language you're writing code in, and then do the reverse in GetVirtualPath

[vezaynk]

It's really going over my head. I don't know to implement a route by myself. I thought of extending the Route class to make a TranslationRoute but Route wants a third parameter in the constructor involving inline constraints which I never even heard of before.

This is my first project in .NET and I may need some hand holding.

[rynowak]

OK thanks for the feedback, I'll get back to you in a bit with a more fleshed out sample.