Optional parameters in routing ending with paging parameter - asp.net

Question

I've been creating a blog, which contains of 3 diffrent views.
- Overview
- Post Detail
- Filtered overview
The filtered overview is based on blogposts which contain a certain tag, to make the url pretty I would love to get it like to be able to add optional parameters like the following:
mydomain.com/blog/<tagname>/<page>
mydomain.com/blog/<tagname1>/<tagname2>/<page>
mydomain.com/blog/<tagname1>/<tagname2>/<tagname3>/<page>
The pageing parameter is semi-optional, if not there it should be 1. But in most cases it will be there.
Are there ways to solve this issue in a nice way?
The only way I could think of was creating a lot of lines in my global asax which makes it kind of messy in my opinion.
Thanks in advance, DerDee

Answer 1

You could write a custom route:
public class BlogRoute : Route
{
public BlogRoute()
: base(
"blog/{*info}",
new RouteValueDictionary(new
{
controller = "blog",
action = "index"
}),
new MvcRouteHandler()
)
{
}
public override RouteData GetRouteData(HttpContextBase httpContext)
{
var rd = base.GetRouteData(httpContext);
if (rd == null)
{
return null;
}
var info = rd.Values["info"] as string;
if (string.IsNullOrEmpty(info))
{
return rd;
}
var parts = info.Split('/');
if (parts.Length < 1)
{
return rd;
}
for (int i = 0; i < parts.Length; i++)
{
if (i == parts.Length - 1)
{
int page;
if (int.TryParse(parts[i], out page))
{
rd.Values["page"] = page;
}
}
if (!rd.Values.ContainsKey("page"))
{
rd.Values[string.Format("tags[{0}]", i)] = parts[i];
}
}
return rd;
}
}
which will be registered in Global.asax:
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.Add("BlogRoute", new BlogRoute());
routes.MapRoute(
"Default",
"{controller}/{action}/{id}",
new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
and then you could have a BlogController:
public class BlogController : Controller
{
public ActionResult Index(string[] tags, int? page)
{
...
}
}

Answer 2

You can't have optional parameters come before required parameters in MVC. One solution would be to put the paging parameter before the tags parameter:
mydomain.com/blog/<page>/<tagname>
mydomain.com/blog/<page>/<tagname1>/<tagname2>
mydomain.com/blog/<page>/<tagname1>/<tagname2>/<tagname3>
You can then give a default value to the page parameter in your route:
MapRoute(null, "blog/{page}/{*tagNames}",
new { controller = "Blogs", action = "ByPageAndTags", page = 1 });