Alter MVC Routing with dynamic prefix while maintaining backwards url compatibility - asp.net-mvc-2

Question

As it is not, I have a site where you must come in on a single url and a cookie is set to track which customer you are affiliated with. I want to change this so that certain controllers only use a url like this:
/{friendlyName}/{controller}/{index}/{id}
that friendly name is unique and lets me select the correct customer without using the cookie kludge.
I have controllers: Home, Redirect that I do not want the friendly name part of (and possibly more).
I have a few others that fit this category that I would like to move into their own areas. How can I not include the areas as valid friendly names? For instance, I have a controller that services up content in an iframe called Framed. currently, a url for this looks like /Framed/action/id. I could put this in an area called Framed with a controller the same name as the action, and I should still be able to maintain the same url.
For the controller Error I want the friendly name to be optional
I have other controllers that I want the friendly name to be required: SignIn, SignOut, Account
Once I have the routing, the problem is altering the code so that my redirects maintain the friendlyurl. Any ideas on how to do that?
My problem is just coming up with a good plan of attack on how to change the routing of my site. I must maintain backwards compatibility of some of the urls - namely anything I don't want the friendly url part of, including the controllers I discussed slitting into their own areas. I'm looking for any good suggests on how to lay this out and go about altering the changes.

Answer 1

To accomplish your objectives, you will need a combination of routes and RouteConstraints. Also, you will need to enforce rules that a friendlyName is unique, and is different from the names of any controllers or areas.
The following routes should be sufficient in RegisterRoutes() in Global.asax.cs:
routes.MapRoute(
"WithFriendlyName",
"{friendlyName}/{controller}/{index}/{id}",
new { controller = "Home", action = "Index", id = UrlParameter.Optional },
new { friendlyName = new MustBeFriendlyName() }
);
routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "Home", action = "Index", id = UrlParameter.Optional },
new { controller = new MustNotRequireFriendlyName() }
);
The RouteConstraints should look something like this:
using System;
using System.Web;
using System.Web.Routing;
namespace Examples.Extensions
{
public class MustBeFriendlyName : IRouteConstraint
{
public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
{
// return true if this is a valid friendlyName
// MUST BE CERTAIN friendlyName DOES NOT MATCH ANY
// CONTROLLER NAMES OR AREA NAMES
var _db = new DbContext();
return _db.FriendlyNames.FirstOrDefault(x => x.FriendlyName.ToLowerInvariant() ==
values[parameterName].ToString().ToLowerInvariant()) != null;
}
}
public class MustNotRequireFriendlyName : IRouteConstraint
{
private const string controllersRequiringFriendlyNames =
"SignIn~SignOut~Account";
public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
{
// return true if this controller does NOT require a friendlyName
return controllersRequiringFriendlyNames.ToLowerInvariant()
.Contains(values[parameterName].ToString().ToLowerInvariant());
}
}
}
This should get you started.
As far as the URLs generated by your redirects, if the routing is set up correctly, the URL generation should follow, so that the only changes you are likely to need are those to insure {friendlyName} is being passed.
You probably will have to add some additional routes and constraints as you get further into your changes.

Answer 2

Just wanted to add to this, as the optional prefix been biting me for the past couple of days. While I want to use the solution provided by #counsellorben, I also needed to be able to address the routes by the same name, which is impossible when using 2 routes.
It took me some headscratching, but finally the solution actually seemed very simple. I just needed to create an intermediate aggregate route:
public class AggregateRoute : RouteBase
{
private readonly RouteBase[] _routes;
public AggregateRoute(params RouteBase[] routes)
{
_routes = routes;
}
public override RouteData GetRouteData(HttpContextBase httpContext)
{
RouteData routeData = null;
foreach (var route in _routes)
{
routeData = route.GetRouteData(httpContext);
if (routeData != null) break;
}
return routeData;
}
public override VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values)
{
VirtualPathData virtualPath = null;
foreach (var route in _routes)
{
virtualPath = route.GetVirtualPath(requestContext, values);
if (virtualPath != null) break;
}
return virtualPath;
}
}
This allows me to do:
routes.Add(
"RouteName",
new AggregateRoute(
new Route("{path}", new MvcRouteHandler()),
new Route("{prefix}/{path}", new MvcRouteHandler())
)
);
Which enables resolving either route by the same name, which is impossible when adding both routes separately:
Url.RouteLink("RouteName", new RouteValueDictionary{
new{path="some-path"}});
Url.RouteLink("RouteName", new RouteValueDictionary{
new{path="some-prefix/some-path"}});