How to pass Request.QueryString to Url.Action?

If you want to easily be able to add additional route value parameters to your Url.Action, try this extension method (based on Linefeed’s) which takes an anonymous object and returns a RouteValueCollection:

public static RouteValueDictionary ToRouteValues(this NameValueCollection col, Object obj)
{
    var values = new RouteValueDictionary(obj);
    if (col != null)
    {
        foreach (string key in col)
        {
            //values passed in object override those already in collection
            if (key != null && !values.ContainsKey(key)) values[key] = col[key];
        }
    }
    return values;
}

Then you can use it like so:

Url.Action("action", "controller", Request.QueryString.ToRouteValues(new{ id=0 }));