Url.Action based on the current route - asp.net-mvc

Question

I'd like to generate a new URL based on the existing route, but will add a new parameter 'page'
Here are a few examples:
old: ~/localhost/something?what=2
new: ~/localhost/something?what=2&page=5
old: ~/localhost/Shoes
new: ~/localhost/Shoes/5
I can not just append &page=5 to existing url because routes may be different.
Some use the query string and some do not.

Answer 1

I had a similar issue, and took the approach of extending the UrlHelper. The code in the View looks like:
Page 2
The UrlHelper extension looks like:
using System.Web.Mvc;
using System.Web.Routing;
using System.Collections.Specialized;
public static class UrlHelperExtension
{
public static string AddPage(this UrlHelper helper, int page)
{
var routeValueDict = new RouteValueDictionary
{
{ "controller", helper.RequestContext.RouteData.Values["controller"] },
{ "action" , helper.RequestContext.RouteData.Values["action"]}
};
if (helper.RequestContext.RouteData.Values["id"] != null)
{
routeValueDict.Add("id", helper.RequestContext.RouteData.Values["id"]);
}
foreach (string name in helper.RequestContext.HttpContext.Request.QueryString)
{
routeValueDict.Add(name, helper.RequestContext.HttpContext.Request.QueryString[name]);
}
routeValueDict.Add("page", page);
return helper.RouteUrl(routeValueDict);
}
}
A couple of notes: I check for the ID, since I don't use it in all my routes. I add the Page route value at the end, so it is the last url parameter (otherwise you could add it in the initial constructor).

Answer 2

This seems like a good approach:
// Clone Current RouteData
var rdata = new RouteValueDictionary(Url.RequestContext.RouteData.Values);
// Get QueryString NameValueCollection
var qstring = Url.RequestContext.HttpContext.Request.QueryString;
// Pull in QueryString Values
foreach (var key in qstring.AllKeys) {
if (rdata.ContainsKey(key)) { continue; }
rdata[key] = qstring[key];
}
// Update RouteData
rdata["pageNo"] = "10";
// Build Url
var url = Url.RouteUrl(rdata);
and it avoids collisions such as ?controller=example&action=problem etc.

Answer 3

You could reconstruct a url by pulling out the parts of the existing route by way of the RouteData object. For instance, the following would render a url with the controller and action of the current route:
<%=Url.RouteUrl(new { controller = ViewContext.RouteData.Values["controller"],
action = ViewContext.RouteData.Values["action"] }) %>
To get you started, you could go with something like a custom extension method that generates the url with an additional "page" parameter. Adjust as necessary:
public static string UrlWithPage(this UrlHelper urlHelper, string name, int page)
{
string url = urlHelper.RouteUrl(
new {
controller = urlHelper.RequestContext.RouteData.Values["controller"],
action = urlHelper.RequestContext.RouteData.Values["action"],
id = urlHelper.RequestContext.RouteData.Values["id"],
page = page
}
);
return "" + name + "";
}
This will construct a properly formatted link based on the routing configuration, whether page is real segment in the url or just appended as a querystring.