CODEWITHSUNDEEP
asp.netasp.net-mvc-3asp.net-mvc-routingaction-filter
Arnab Chakraborty
Arnab Chakraborty

Reputation: 7472

Adding parameters to QueryString from ActionFilter

I am trying to write a custom ActionFilter which will append a request id to the QueryString if it doesn't already have one.

Something like this : 

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        base.OnActionExecuting(filterContext);

        Controller controller = (Controller)filterContext.Controller;
        HttpRequestBase request = filterContext.HttpContext.Request;

        // New request
        if (request.QueryString[REQUEST_ID_KEY] == null)
        {
            string requestId = Utility.GetNewUniqueId();
            controller.Session[REQUEST_ID_KEY] = requestId;

            ////////////////////////////////////////
            // Add request id to query string ...???
            ////////////////////////////////////////

            return;
        }

    }

One way to add the parameter to the query string which I found was to redirect the action to itself with the request id added to the route values, like this :

  RouteValueDictionary redirectTargetDictionary = new RouteValueDictionary();
  redirectTargetDictionary.Add("action", actionName);
  redirectTargetDictionary.Add("controller", controllerName);
  redirectTargetDictionary.Add(REQUEST_ID_KEY, requestId);

  filterContext.Result = new RedirectToRouteResult(redirectTargetDictionary);

But this kind of seems like a hack. Is there a better way to add parameters to the QueryString? (note that my aim is to achieve a ActionFitler which rewrites urls, so I have to pass the parameter in the QueryString).

Upvotes: 2

Views: 5098

Answers (1)

Josh
Josh

Reputation: 44906

I believe that by the time the routing engine has been engaged you won't be able to re-write URLs. Routing doesn't really work that way.

You can however manipulate the action values that get used to invoke an Action by using a filter. Phil Haack has an article explaining this exact approach.

Upvotes: 1

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