How to add QueryString in OnActionExecuting()?

Question

i want to add two queryString in current request URL if it is not exsist

Edited:

I tried this ---

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
if (filterContext.RequestContext.HttpContext.Request.QueryString["mid"] == null && filterContext.RequestContext.HttpContext.Request.QueryString["mod"] == null)
{
mid = Convert.ToString(HttpUtility.ParseQueryString(filterContext.RequestContext.HttpContext.Request.UrlReferrer.Query)["mid"]);
mod = Convert.ToString(HttpUtility.ParseQueryString(filterContext.RequestContext.HttpContext.Request.UrlReferrer.Query)["mod"]);
if (!string.IsNullOrEmpty(mid) || !string.IsNullOrEmpty(mod))
{
RouteValueDictionary redirecttargetDictionary = new RouteValueDictionary();
NameValueCollection Qstr = null;
if (filterContext.HttpContext.Request.RequestType == "GET")
{
Qstr = HttpUtility.ParseQueryString(filterContext.HttpContext.Request.Url.Query);
foreach (string item in Qstr)
{
redirecttargetDictionary.Add(item, Qstr[item]);
}
if (Qstr["mid"] == null)
{
redirecttargetDictionary.Add("mid", mid);
}
if (Qstr["mod"] == null)
{
redirecttargetDictionary.Add("mod", mod);
}
filterContext.Result = new RedirectToRouteResult(redirecttargetDictionary);
}
}
}

This code works fine. -check for quesrystring exsist if no -then take qstring value from 'Urlreferrer' -if request type is GET -then add two querystring with exsisting querystring

But but I having problem if querystring in current request has null value url like http://localhost:53372/question/index?type=&stage.if this ll b the current request url then code ll check for mid n mod qstring as its not exsist it will add both the qstring with exsisting type n stage but value ll b null then before hitting action again OnActionExecuting() get call this time first 'if' is not true and then index method get call but I m not getting type n stage querystring which suppose to null I found url in address bar is http://localhost:53372/question/index?mid=1&mod=5. If I remove filter the I got URL http://localhost:53372/question/index?type=&stage=&mid=1&mod=5 here I m getting both stage n type querystring though its null.

Edited--

[HttpGet]
        public ActionResult Index(ProjectType? projectType, int? projectStageID, int? page)
        {
            int currentPageIndex = page.HasValue ? page.Value - 1 : 0;
            IPagedList<ProjectModule> moduleList = null;
            IDictionary<string, string> queryParam = new Dictionary<string, string>();
            queryParam["ProjectType"] = string.Empty;
            queryParam["ProjectStageID"] = string.Empty;
            ViewBag.ProjectType = null;
            ViewBag.ProjectStage = null;
            ViewBag.message = "";
            if ((projectType != null || projectType.HasValue) && projectStageID.HasValue && page.HasValue)
            {

                queryParam["ProjectType"] = Request.QueryString["ProjectType"];
                queryParam["ProjectStageID"] = Request.QueryString["ProjectStageID"];
                //
                //Set View Bag
                //
                ViewBag.ProjectType = Enum.Parse(typeof(ProjectType), Request.QueryString["ProjectType"]);
                ViewBag.ProjectStage = Convert.ToInt32(Request.QueryString["ProjectStageID"]);
                //
                // Set Query String formcollection for Pagging purpose
                //           
                ViewBag.QueryParam = queryParam;
                moduleList = new ProjectModuleService().GetProjectModulesByProjectStageID(Convert.ToInt32(Request.QueryString["ProjectStageID"])).ToPagedList(currentPageIndex, Utility.ConstantHelper.AdminDefaultPageSize); ;
                if (moduleList.Count == 0)
                {
                    ViewBag.message = "Record(s) not found.";
                }
                return View(moduleList);

            }
            else
            {
                if (!string.IsNullOrEmpty(Request.QueryString["ProjectType"]) && !string.IsNullOrEmpty(Request.QueryString["ProjectStageID"]) && !string.Equals(Request.QueryString["ProjectStageID"], "0"))
                {
                    if (!string.IsNullOrEmpty(Request.Params.Get("Index")))
                    {
                        queryParam["ProjectType"] = Request.QueryString["ProjectType"];
                        queryParam["ProjectStageID"] = Request.QueryString["ProjectStageID"];
                        //
                        //Set View Bag
                        //
                        ViewBag.ProjectType = Enum.Parse(typeof(ProjectType), Request.QueryString["ProjectType"]);
                        ViewBag.ProjectStage = Convert.ToInt32(Request.QueryString["ProjectStageID"]);
                        //
                        // Set Query String formcollection for Pagging purpose
                        //           
                        ViewBag.QueryParam = queryParam;
                        moduleList = new ProjectModuleService().GetProjectModulesByProjectStageID(Convert.ToInt32(Request.QueryString["ProjectStageID"])).ToPagedList(currentPageIndex, Utility.ConstantHelper.AdminDefaultPageSize); ;
                        if (moduleList.Count == 0)
                        {
                            ViewBag.message = "Record(s) not found.";
                        }
                        return View(moduleList);
                    }

                    else if (!string.IsNullOrEmpty(Request.Params.Get("Create")))
                    {
                        return RedirectToAction("Create", new { projectStageID = Convert.ToInt32(Request.QueryString["ProjectStageID"]) });
                        //return RedirectToAction("Create", new { projectStageID = Convert.ToInt32(Request.QueryString["ProjectStageID"]), projectType = Enum.Parse(typeof(ProjectType), Request.QueryString["ProjectType"]) });
                    }

                }
                if (Request.QueryString["ProjectType"] == "" || Request.QueryString["ProjectStageID"] == "" || string.Equals(Request.QueryString["ProjectStageID"], "0"))
                {
                    ViewBag.message = "Please select all fields.";
                    return View();
                }
                return View();
            }
        }

What I m doing wrong?

Answer 1

Here what I understand that if there are no querystring in the URL,you need to add two query string parameters. If you are adding this two querystring parameters explicitly than, it will be default value for that queryparameters.

It's better to provide default value in action method instead of adding queryparameters in URL. You can achieve by following code.

public ActionResult ComposeEmail(int queryParameter1 = 0,string queryParameter2 = string.Empty)
{
}

Do let me know, if you have any query.