Dropdownlist onchanged - Trouble persisting ViewModel

**Sl1ver** · Apr 15 '15, 08:59 PM

I'm creating a register page and I have 3 dropdowns.

Now the first dropdown must load first go to load the countries. Based on that I load the provinces and then based on that I load the cities in that province.

The trouble I'm having is that on the first change it keeps my selected value but on the second onchange it seems as everything is lost.

I load the reigster view by just loading countries so long. then the javascript posts it to an action.

cshtml

Code:

     <label class="col-md-3 col-xs-5 control-label">Country:</label>
                            <div class="col-md-9 col-xs-7">
                                @Html.DropDownListFor(x => x.CountryId, (IEnumerable<SelectListItem>)ViewBag.CountryItems, "Please Select", new { @class = "form-control select", @onchange = "CallChangefunc(this.value, null)" })
                            </div>
                        </div>
                        <div class="form-group">
                            <label class="col-md-3 col-xs-5 control-label">Province:</label>
                            <div class="col-md-9 col-xs-7">
                                    @Html.DropDownListFor(x => x.ProvinceId, (IEnumerable<SelectListItem>)ViewBag.ProvinceItems, "Please Select", new { @class = "form-control select", @onchange = "CallChangefunc(null, this.value)" })
                            </div>
                        </div>
                        <div class="form-group">
                            <label class="col-md-3 col-xs-5 control-label">City:</label>
                            <div class="col-md-9 col-xs-7">
                                @Html.DropDownListFor(x => x.CityId, (IEnumerable<SelectListItem>)ViewBag.CityItems, "Please Select", new { @class = "form-control select" })
                            </div>
                        </div>

javascript

Code:

function CallChangefunc(countryId, provinceId) {
        window.location.href = "/Master/SetDropDowns?provinceId=" + provinceId + "&countryId=" + countryId ;
    }

First one "Register" loads 1'st then SetDropDowns gets called onchanged.

I load the viewbags(Select edItemLists) otherwise I get errors on refresh. is there a better way to code the viewbags to not have in two places?

Code:

 [HttpGet]
        public ActionResult Register()
        {
            IEnumerable<SelectListItem> CountryItems = BusinessAPI.CountryManager.GetAllCountries().Select(ci => new SelectListItem
                {
                    Value = ci.Id.ToString(),
                    Text = ci.Name
                });

            ViewBag.CountryItems = CountryItems;

            IEnumerable<SelectListItem> ProvinceItems = BusinessAPI.ProvinceManager.GetAllProvincesByCountryId(0).Select(ci => new SelectListItem
            {
                Value = ci.Id.ToString(),
                Text = ci.Name
            });

            ViewBag.ProvinceItems = ProvinceItems;

            IEnumerable<SelectListItem> CityItems = BusinessAPI.CityManager.GetAllCitiesByProvinceId(0).Select(ci => new SelectListItem
            {
                Value = ci.Id.ToString(),
                Text = ci.Name
            });

            ViewBag.CityItems = CityItems;

            return View();
        }

        public ActionResult SetDropDowns(string provinceId, string countryId)
        {
            IEnumerable<SelectListItem> CountryItems = BusinessAPI.CountryManager.GetAllCountries().Select(ci => new SelectListItem
            {
                Value = ci.Id.ToString(),
                Text = ci.Name
            });

            ViewBag.CountryItems = CountryItems;

            int countId = 0;
            if (countryId == "null")
                countryId = string.Empty;

            if (TempData["CountryId"] == null)
            {
                if (!string.IsNullOrEmpty(countryId))
                {
                    countId = Convert.ToInt32(countryId);
                    TempData["CountryId"] = countId;
                }
            }
            else
                countId = Convert.ToInt32(TempData["ProvinceId"]);

            IEnumerable<SelectListItem> ProvinceItems = BusinessAPI.ProvinceManager.GetAllProvincesByCountryId(Convert.ToInt32(countId)).Select(ci => new SelectListItem
            {
                Value = ci.Id.ToString(),
                Text = ci.Name
            });

            ViewBag.ProvinceItems = ProvinceItems;

            int provId = 0;
            if (provinceId == "null")
                provinceId = string.Empty;

            if (TempData["ProvinceId"] == null)
            {
                if (!string.IsNullOrEmpty(provinceId))
                {
                    provId = Convert.ToInt32(provinceId);
                    TempData["ProvinceId"] = provId;
                }
            }
            else
                provId = Convert.ToInt32(TempData["ProvinceId"]);

            IEnumerable<SelectListItem> CityItems = BusinessAPI.CityManager.GetAllCitiesByProvinceId(provId).Select(ci => new SelectListItem
            {
                Value = ci.Id.ToString(),
                Text = ci.Name
            });

            ViewBag.CityItems = CityItems;

            return View("Register");
        }