Url with email address in ASP.NET MVC4 - asp.net-mvc-4

Question

I have a situation where I'm using URLs that could possibly contain email addresses. For example:
http://MyUrl.com/Edit/Mike
or
http://MyUrl.com/Edit/bob#whatever.com
According to this StackOverflow question it appears the easy way to get around this is to use a querystring instead. Is there a way I could set this up in the routing rule, where it would determine if value is invalid and have it fall back to a querystring?

Answer 1

How about this:
Route:
routes.MapRoute(
name: "UserEdit",
url: "Edit/{user}",
defaults: new { controller = "User", action = "Edit" },
constraints: new { user = #"[a-z0-9]+" /*Add valid characters here*/ }
);
routes.MapRoute(
name: "UserEditWithIllegalChars",
url: "Edit/",
defaults: new { controller = "User", action = "Edit" }
);
The route will only match URLs like /Edit/Mike and Edit/?user=bob#whatever.com.
Generating the URL also works. For example
#Html.ActionLink("1", "Edit", "User", new { user = "Mike" }, new { })
#Html.ActionLink("2", "Edit", "User", new { user = "bob#whatever.com" }, new { })
Produces the same URLs as above
Controller:
public ActionResult Edit(string user)
Note:
1) you need to check if user is null
2) add valid characters into the constraint because I don't know all of them.