ASP.NET Routing and Regular Expressions

Question

I am trying to enable a route like the following

route = new Route("{w1}-{c1}-{n1},{w2}-{c2}-{n2}", new ResultRouteHandler());
route.Constraints = new RouteValueDictionary();
route.Constraints.Add("c1", "(.*)|([-])");
route.Constraints.Add("c2", "(.*)|([-])");
RouteTable.Routes.Add(route);

However I run into a problem when c1 or c2 is "-". For example "a-b-c,d---f" returns 404 (whilst "a-b-c,d-e-f" works fine). Anyone has a clue what am I doing wrong? Thank you in advance.

EDIT:

I found a simple workaround for this problem:

route = new Route("{w1}-{c1}-{n1},{w2}---{n2}", new MyRouteHandler());
RouteTable.Routes.Add(route);
route = new Route("{w1}-{c1}-{n1},{w2}-{c2}-{n2}", new MyRouteHandler());
RouteTable.Routes.Add(route);

If c2 is "-" we match to the first route, otherwise to the second.

Answer 1

I'm not 100% positive about the regex implementation, but it should look like this I think:

route.Constraints.Add("c1", "([^-]*)");
route.Constraints.Add("c2", "([^-]*)");

Answer 2

If I'm understanding correctly, you do want to match "a-b-c,d---f" which is why you're tweaking the constraints in the first place. The Regex you have there is kind of redundant though as '-' will be matched by the '.*'. In other words, I don't think your Regex is to blame but rather the routing engine parser.

If you change your route from "{w1}-{c1}-{n1},{w2}-{c2}-{n2}" to "{w1}-{c1}-{n1},{w2}_{c2}-{n2}", then c2 will start matching the '-' in "a-b-c,d_--f". I think something about the parsing of routes doesn't like using a delimiter as the next value.

So I think you can drop your constraints (as they currently exist), but you might need to organize your URLs a little differently if you want '-' to be c1 or c2.