How to get all active parameters in ASP.NET MVC (2)

I was wondering if there is a way to create ActionLink

or a similar one that only changes a few parameters of the actual request and keeps all other parameters intact. For example, if I have a url, for example http://example.com/Posts/Index?Page=5&OrderBy=Name&OrderDesc=True

, I only want to change a parameter Page

or OrderBy

and keep all other parameters the same, even the ones I don't know about yet (for example, when I want to add a parameter Search

or something like that).

The title of my current activity looks like this:

public ActionResult Index(int? Page, string OrderBy, bool? Desc)

      

        
        
        
      

    

and I am only interested in the values ​​that this controller "eats". However, I want that when extending this action (with a parameter, for example string Search

) the links should work the same as before.

Here's what I've already done:

• Create a new one RouteValueDictionary
  
  and fill it with everything fromRouteData.Values
  
  
  • Problem. This only fills in the parameters that are used in routing, so all other optional parameters (for example Page
    
    ) for the controller are lost.
• Add all from HttpContext.Request.QueryString
  
  to the previous dictionary
  • This is what I am currently using
  • Problem: It might have some unwanted things that the controller didn't ask for, and it doesn't work if the page was POST loaded. You also don't have ModelBindings (but that's not a big problem because we're forwarding everything anyway)
• Use HttpContext.Request.Params
  
  
  • Problem: It has too much garbage data that imho shouldn't be added to RouteValueDictionary
    
    which is being passed toActionLink
    
    

So the questions:

• Is there one RVD
  
  that has all the data that was transmitted to the controller and was used by it?
• Is this a good solution, or are there any caveats that I haven't thought of (mostly in the context of modifying multiple query parameters while keeping others intact)?
• Is there a way to filter out "unwanted" data from an object Params
  
  ?

EDIT: Checked the variable RouteData.DataTokens

, but it's usually empty and doesn't contain everything I need. It seems to contain only the parameters required for routing, but not all parameters.