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How can I populate a dropdownlist based on the selected value of another dropdownlist? MVC

I am currently trying to populate the values for a car's model based on the selected make in a dropdownlist. I am new to coding so I am not sure what my mistake is. The project doesn't give me any errors but no values are displayed when I selected the make.
This is my Partial View that I am adding into my Create View.
#model IgnitionHubPractice.Models.MakeModelDorpdownView
<div class="form-horizontal">
<div class="form-group">
#if (ViewBag.MakeList != null)
{
#Html.DropDownListFor(m => m.MakeID, ViewBag.MakeList as SelectList, "--Select Make--", new { #class = "form-control" })
}
</div>
<div class="form-group">
#Html.DropDownListFor(m => m.ModelID, new SelectList(" "), "--Select Model--", new { #class = "form-control" })
</div>
</div>
<script>
$(document).ready(function () {
$("#MakeID").change(function () {
$.get("/Cars/GetModelList",{ MakeID: $("MakeID").val() }, function (data) {
$("#ModelID").empty();
$.each(data, function (index, row) {
$("#ModelID").append("<option value ='" + row.ModelID + "' >" + row.Name + </option>")
});
});
})
});
</script>
This is my controller
public ActionResult Create([Bind(Include = "CarID,Year,Color,Mileage,Cost,MarketValue,BodyType,Drive,Notes,Available,VinNumber,CarLotID,ModelID")] Car car, [Bind(Include ="MakeID,Name")] Make make)
{
if (ModelState.IsValid)
{
db.Cars.Add(car);
db.SaveChanges();
return RedirectToAction("Index");
}
List<Make> MakeList = db.Makes.ToList();
ViewBag.MakeList = new SelectList(db.Makes, "MakeID", "Name", make.MakeID);
ViewBag.ModelID = new SelectList(db.Models, "ModelID", "Name", car.ModelID);
ViewBag.CarLotID = new SelectList(db.CarLots, "CarLotID", "LotName", car.CarLotID);
return View(car);
}
public JsonResult GetModelList(int MakeID)
{
db.Configuration.ProxyCreationEnabled = false;
List<Model> ModelList = db.Models.Where(x => x.MakeID == MakeID).ToList();
return Json(ModelList, JsonRequestBehavior.AllowGet);
}
Please help, thanks in advance.

In MVC you try to create a cascading drop down. So for easy understanding you can check the below link. It contanin detailed information for controller and View with Jquery part.
Please visit this link: Cascading Drop down List With MVC And AJAX

Checkboxes with array model in angularjs using asp.mvc

I am using Asp.MVC 5 for an application and I want to generate many checkboxes with different angularjs models, and I thought the best option is by using array model in angularjs. I tried the code below inside a foreach:
#{
int i = 0;
foreach (var selectedVesselViewModel in Model.SelectedVesselViewModels)
{
using (Html.BeginForm("SelectNotificaiton", "Admin", new { area = "DashBoard" }, FormMethod.Post, new { id = "filterVesselsForm_" + i}))
{
#Html.HiddenFor(item => selectedVesselViewModel.VesselId, new {ng_model= "SelectedVessels[" + i + "].VesselId" })
<li class="row">
<div class="col-md-10">
<a href="#" class="text-admin-area">
#selectedVesselViewModel.VesselName
</a>
</div>
<div class="col-md-2">
<div class="pull-right">
<div class="checkbox checkbox-inline">
#Html.CheckBoxFor(item => selectedVesselViewModel.Selected,
new {id = "SelectedVesselViewModels_"+i+"__Selected",
onchange ="document.getElementById('filterVesselsForm_"+i+"').submit()",
ng_model = "SelectedVessels[" + i + "].Selected"
})
<label for="SelectedVesselViewModels_#(i++)__Selected"></label>
</div>
</div>
</div>
</li>
}
}
}
i variable is an incrementing variable:
in the angularjs controller I have something like this:
(function (app) {
"use strict";
app.controller("DashboardCtrl", ['$scope',
function ($scope) {
function init() {
// $scope.SelectedVessels = [];
}
$scope.SelectedVessels = [];
init();
$scope.RefreshSideBarVessels = function() {
angular.forEach($scope.SelectedVessels, function (value, key) {
alert($scope.SelectedVessels[key].VesselId);
});
}
}]);
})(adminModule);
When I use angularjs foreach loop the $scope.SelectedVessels seems to be empty but I dont know why!
angular.forEach($scope.SelectedVessels, function (value, key) {
alert($scope.SelectedVessels[key].Selected);
});
Does anybody know where is the problem, why I cant access the inner properties of the $scope.SelectedVessels array and why it is empty ?

How you are adding values to your array ie. $scope.SelectedVessels is important
Please have a look at below example.
var values = {name: 'Raja', gender: 'male'};
var log = [];
angular.forEach(values, function(value, key) {
this.push(key + ': ' + value);
}, log);
expect(log).toEqual(['name: Raja', 'gender: male']);

Here is the solution to this problem:
I had to use ng-init to each checkbox to instantiate the ng-model.
#Html.CheckBoxFor(item => selectedVesselViewModel.Selected,
new {id = "SelectedVesselViewModels_"+i+"__Selected",
onchange ="document.getElementById('filterVesselsForm_"+i+"').submit()",
ng_model = "SelectedVessels[" + i + "].Selected",
ng_init = "SelectedVessels[" + i + "].Selected="+ selectedVesselViewModel.Selected.ToString().ToLower()
})

First off , its ng-model not ng_model (- vs _) but that could be typo.
Second, try this code
$scope.onChange = function (index, value) {
$scope.SelectedVessels[index] = value;
}
#Html.CheckBoxFor(item => selectedVesselViewModel.Selected,
SelectedVessels[i] = selectedVesselViewModel.Selected
new {id = "SelectedVesselViewModels_"+i+"__Selected",
onchange ="document.getElementById('filterVesselsForm_"+i+"').submit()",
ng-model = "SelectedVessels[" + i + "].Selected",
on-change="onChange(i,selectedVesselViewModel.Selected)
})

Repopulate Dropdown List After Ajax Request [duplicate]

This is how i am loading on page load state and city dropdown:
My Controller method:
This is the first method which is calling when page is loaded.
public ActionResult Index()
{
var states = GetStates();
var cities = Enumerable.Empty<SelectListItem>();
ViewBag.States = states;
ViewBag.Cities = cities;
}
private IEnumerable<SelectListItem> GetStates()
{
using (var db = new DataEntities())
{
return db.States.Select(d => new SelectListItem { Text = d.StateName, Value =d.Id.ToString() });
}
}
[HttpGet]
public ActionResult GetCities(int id)
{
using (var db = new DataEntities())
{
var data = db.Cities.Where(d=>d.StateId==id).Select(d => new { Text = d.CityName, Value = d.Id }).ToList();
return Json(data, JsonRequestBehavior.AllowGet);
}
}
My View:
IEnumerable<SelectListItem> States = ViewBag.States;
IEnumerable<SelectListItem> Cities = ViewBag.Cities;
#Html.DropDownList("State", States, "Select State", new { onchange="loadCities(this)"})
#Html.DropDownListFor(m => m.CityId, Cities, "Select City", new { id="ddlCity"})
function loadCities(obj) {
$.ajax({
url: "/Home/GetCities",
data: { id: $(obj).val() },
contentType:"application/json",
success:function(responce){
var html = '<option value="0">Select City</option>';
$(responce).each(function () {
html += '<option value="'+this.Value+'">'+this.Text+'</option>'
});
$("#ddlCity").html(html);
}
});
}
Any better way then this to load state and city dropdown?
public class HomeController : Controller
{
public ActionResult Index(int id=0)
{
Person model = null;
var states = GetStates().ToList();
var cities = Enumerable.Empty<SelectListItem>();
if (id > 0)
{
using (var db = new DataEntities())
{
model = db.People.Include("City").FirstOrDefault(d => d.Id == id);
if (model == null)
model = new Person();
else
{
states.First(d => d.Value == model.City.StateId.ToString()).Selected = true;
cities = db.Cities.Where(d => d.StateId == model.City.StateId).ToList().Select(d => new SelectListItem { Text = d.CityName,Value=d.Id.ToString(),Selected=d.Id==model.CityId });
}
}
}
else
{
model = new Person();
}
ViewBag.States = states;
ViewBag.Cities = cities;
ViewBag.Persons = GetPersons();
return View(model);
}
[HttpGet]
public ActionResult GetCities(int id)
{
using (var db = new DataEntities())
{
var data = db.Cities.Where(d=>d.StateId==id).Select(d => new { Text = d.CityName, Value = d.Id }).ToList();
return Json(data, JsonRequestBehavior.AllowGet);
}
}
public ActionResult SavePersonDetail([Bind(Exclude = "Id")] Person model)
{
// var employeeDal= new Emploee();
//employee.firstname=model.
if (ModelState.IsValid)
{
var Id = model.Id;
int.TryParse(Request["Id"], out Id);
using (var db = new DataEntities())
{
if (Id > 0)
{
var person = db.People.FirstOrDefault(d => d.Id == Id);
if (person != null)
{
model.Id = Id;
db.People.ApplyCurrentValues(model);
}
}
else
{
db.People.AddObject(model);
}
db.SaveChanges();
}
}
if (!Request.IsAjaxRequest())
{
ViewBag.States = GetStates();
ViewBag.Persons = GetPersons();
ViewBag.Cities = Enumerable.Empty<SelectListItem>();
return View("Index");
}
else
{
return PartialView("_personDetail",GetPersons());
}
}
public ActionResult Delete(int id)
{
using (var db = new DataEntities())
{
var model = db.People.FirstOrDefault(d => d.Id == id);
if (model != null)
{
db.People.DeleteObject(model);
db.SaveChanges();
}
}
if (Request.IsAjaxRequest())
{
return Content(id.ToString());
}
else
{
ViewBag.States = GetStates();
ViewBag.Persons = GetPersons();
ViewBag.Cities = Enumerable.Empty<SelectListItem>();
return View("Index");
}
}
private IEnumerable<SelectListItem> GetStates()
{
using (var db = new DataEntities())
{
return db.States.ToList().Select(d => new SelectListItem { Text = d.StateName, Value =d.Id.ToString() });
}
}
private IEnumerable<Person> GetPersons()
{
using (var db = new DataEntities())
{
return db.People.Include("City").Include("City.State").ToList();
}
}
public ActionResult HomeAjax()
{
ViewBag.States = GetStates();
ViewBag.Cities = Enumerable.Empty<SelectListItem>();
using (var db = new DataEntities())
{
var data = db.States.Include("Cities").Select(d => new { Id = d.Id, Name = d.StateName, Cities = d.Cities.Select(x => new { Id=x.Id,Name=x.CityName}) }).ToList();
ViewBag.CityStateJson = new System.Web.Script.Serialization.JavaScriptSerializer().Serialize(data);
}
ViewBag.Persons = GetPersons();
return View();
}
}
#model IEnumerable<Person>
<div>
<table>
<tr>
<th>
First Name
</th>
<th>
Last Name
</th>
<th>
Email
</th>
<th>
City
</th>
<th>
State
</th>
<th>
Edit
</th>
</tr>
#if (Model.Count() == 0)
{
<tr>
<td colspan="6">
<h3>No data available</h3>
</td>
</tr>
}
else {
foreach (var item in Model) {
<tr data-id="#item.Id">
<td data-id="fn">#item.FirstName</td>
<td data-id="ln">#item.LastName</td>
<td data-id="email">#item.Email</td>
<td data-id="cn">#item.CityName<input type="hidden" value="#item.CityId" /></td>
<td>#item.StateName</td>
<td>
#if (ViewBag.Title == "Home Ajax" || Request.IsAjaxRequest())
{
Update
<span>#Ajax.ActionLink("Delete", "Delete", new { id = item.Id }, new AjaxOptions {OnSuccess="deleteSuccess",OnBegin="showLoader",OnComplete="hideLoader" })</span>
}
else {
<span>#Html.ActionLink("Update", "Index", new { id = item.Id })</span>
<span>#Html.ActionLink("Delete", "Delete", new { id = item.Id })</span>
}
</td>
</tr>
}
}
</table>
</div>
#model Person
#{
ViewBag.Title = "Home Ajax";
IEnumerable<Person> persons = ViewBag.Persons;
IEnumerable<SelectListItem> States = ViewBag.States;
IEnumerable<SelectListItem> Cities = ViewBag.Cities;
IEnumerable<State> fullStates=ViewBag.CityStates;
}
#section featured {
<section class="featured">
<div class="content-wrapper">
<hgroup class="title">
<h1>#ViewBag.Title.</h1>
</hgroup>
</div>
</section>
}
#section styles{
<style type="text/css">
td,th {
border:1px solid;
padding:5px 10px;
}
select {
padding:5px 2px;
width:310px;
font-size:16px;
}
</style>
}
#section scripts{
#Scripts.Render("~/bundles/jqueryval")
<script type="text/javascript">
var jsonArray = #Html.Raw(ViewBag.CityStateJson)
function clearValues() {
$("input[type='text'],select").val('');
$("input[type='hidden'][name='Id']").val(0);
}
function loadCities(obj) {
for (var i = 0; i < jsonArray.length; i++) {
if (jsonArray[i].Id == parseInt($(obj).val())) {
fillCity(jsonArray[i].Cities);
break;
}
}
}
function Edit(obj, Id) {
// alert("hi")
$("input[type='hidden'][name='Id']").val(Id);
var tr = $(obj).closest("tr");
$("#txtfirstName").val($("td[data-id='fn']", tr).text().trim());
$("#txtlastName").val($("td[data-id='ln']", tr).text().trim());
$("#txtemail").val($("td[data-id='email']", tr).text().trim());
var city = $("td[data-id='cn'] input[type='hidden']", tr).val();
var state;
for (var i = 0; i < jsonArray.length; i++) {
for (var j = 0; j < jsonArray[i].Cities.length; j++) {
if (jsonArray[i].Cities[j].Id == parseInt(city)) {
state = jsonArray[i].Id;
break;
}
}
if (state) {
fillCity(jsonArray[i].Cities);
break;
}
}
$("#ddlState").val(state);
$("#ddlCity").val(city);
}
function fillCity(obj) {
var html = '<option value="0">Select City</option>';
$(obj).each(function () {
html += '<option value="' + this.Id + '">' + this.Name + '</option>'
});
$("#ddlCity").html(html);
}
function deleteSuccess(responce) {
alert("record deleted successfully");
$("tr[data-id='" + responce + "']").remove();
}
function insertSuccess() {
alert("Record saved successfully");
clearValues();
}
function showLoader() {
$("#overlay").show();
}
function hideLoader() {
$("#overlay").hide();
}
</script>
}
<h3>Add Personal Detail</h3>
#using (Ajax.BeginForm("SavePersonDetail", "Home", new AjaxOptions { HttpMethod = "POST", UpdateTargetId = "personList" ,OnSuccess="insertSuccess",OnBegin="showLoader",OnComplete="hideLoader"}))
{
#Html.HiddenFor(m => m.Id);
<ol class="round">
<li>
#Html.LabelFor(m => m.FirstName)
#Html.TextBoxFor(m => m.FirstName, new { id = "txtfirstName" })
#Html.ValidationMessageFor(m => m.FirstName)
</li>
<li>
#Html.LabelFor(m => m.LastName)
#Html.TextBoxFor(m => m.LastName, new { id = "txtlastName" })
#Html.ValidationMessageFor(m => m.LastName)
</li>
<li>
#Html.LabelFor(m => m.Email)
#Html.TextBoxFor(m => m.Email, new { id = "txtemail" })
#Html.ValidationMessageFor(m => m.Email)
</li>
<li>
#Html.Label("State")
#Html.DropDownList("State", States, "Select State", new { onchange = "loadCities(this)", id = "ddlState" })
</li>
<li>
#Html.LabelFor(m => m.CityId)
#Html.DropDownListFor(m => m.CityId, Cities, "Select City", new { id = "ddlCity" })
#Html.ValidationMessageFor(m => m.CityId)
</li>
</ol>
<input type="submit" value="Save" />
<input type="button" value="Cancel" onclick="clearValues();"/>
}
<h2>
Person List
</h2>
<div style="position:fixed;text-align:center;top:0;bottom:0;left:0;right:0;z-index:10;background-color:black;opacity:0.6;display:none;" id="overlay">
<img style="position:relative;top:370px" src="~/Images/ajax-loader.gif" />
</div>
<div id="personList">
#Html.Partial("_personDetail", persons)
</div>

You approach using ajax is fine although I would recommend a few better practices including using a view model with properties for StateID, CityID StateList and CityList, and using Unobtrusive JavaScript rather than polluting you markup with behavior, and generating the first ("please select") option with a null value rather than 0 so it can be used with the [Required] attribute
HTML
#Html.DropDownList(m => m.StateID, States, "Select State") // remove the onchange
#Html.DropDownListFor(m => m.CityID, Cities, "Select City") // why change the default ID?
SCRIPT
var url = '#Url.Action("GetCities", "Home")'; // use the helper (dont hard code)
var cities = $('#CityID'); // cache the element
$('#StateID').change(function() {
$.getJSON(url, { id: $(this).val() }, function(response) {
// clear and add default (null) option
cities.empty().append($('<option></option>').val('').text('Please select'));
$.each(response, function(index, item) {
cities.append($('<option></option>').val(item.Value).text(item.Text));
});
});
});
If you were rendering multiple items (say you were asking the user to select their last 10 cities they visited), you can cache the result of the first call to avoid repeated calls where their selections may include cities from the same state.
var cache = {};
$('#StateID').change(function() {
var selectedState = $(this).val();
if (cache[selectedState]) {
// render the options from the cache
} else {
$.getJSON(url, { id: selectedState }, function(response) {
// add to cache
cache[selectedState] = response;
.....
});
}
});
Finally, in response to your comments regarding doing it without ajax, you can pass all the cities to the view and assign them to a javascript array. I would only recommend this if you have a few countries, each with a few cities. Its a matter of balancing the slight extra initial load time vs the slight delay in making the ajax call.
In the controller
model.CityList = db.Cities.Select(d => new { City = d.CountryID, Text = d.CityName, Value = d.Id }).ToList();
In the view (script)
// assign all cities to javascript array
var allCities= JSON.parse('#Html.Raw(Json.Encode(Model.CityList))');
$('#StateID').change(function() {
var selectedState = $(this).val();
var cities = $.grep(allCities, function(item, index) {
return item.CountryID == selectedState;
});
// build options based on value of cities
});

This is a correct approach, but you can simplify your javascript:
function loadCities(obj) {
$.getJSON("/Home/GetCities", function (data) {
var html = '<option value="0">Select City</option>';
$(data).each(function () {
html += '<option value="'+this.Value+'">'+this.Text+'</option>'
});
$("#ddlCity").html(html);
});
}
Further possible simplification:
Add the default item (Select City) server-side, so your javascript will be smaller.

Here's how I'd do it without the page refresh, assuming the list of cities isn't too long.
I'm assuming you can create a GetStatesAndCities method to return a Dictionary.
public ActionResult Index()
{
Dictionary<string, List<String>> statesAndCities = GetStatesAndCities();
ViewBag.StatesAndCities = Json(statesAndCities);
}
Then in the view:
var states = JSON.parse(#ViewBag.StatesAndCities);
function loadCities(obj) {
var cities = states[$(obj).val()];
var html = '<option value="0">Select City</option>';
$(cities).each(function () {
html += '<option value="'+this.Value+'">'+this.Text+'</option>'
});
$("#ddlCity").html(html);
}
This way when the state is changed the cities field with update immediately with no need for callback.

disclaimer: This is not a code answer, there are plenty other answers.
I think best way to keep yourself happy to seperate UI pages from data => turn them into API calls:
/GetCities
/GetStates
Now you can simply leave the select's empty on Razor rendering the page. And use a Jquery/Bootstrap plugin to create an AJAX select box.
This way when the user stops typing his search, this search string can than be send with the AJAX call (eg: /GetStates?search=test) and then a small result set can be send back to the website.
This gives:
Better separation in serveside code
Better User eXperience.
Smaller page loads (since you no longer send all the options to user when he requests the page, only when he opens the select box).

How about using Knockout?
Knockout is a JavaScript library that helps you to create rich, responsive display and editor user interfaces with a clean underlying data model
You have to use ajax for your cities. But with knockout you dont need to write
var html = '<option value="0">Select City</option>';
$(responce).each(function () {
html += '<option value="'+this.Value+'">'+this.Text+'</option>'});
$("#ddlCity").html(html);
in your javascript.Knockout makes it simple.
You can simply write:
function CityModel() {
var self = this; // that means this CityModel
self.cities = ko.observableArray([]);
self.getCities = function () {
$.ajax({
url: "/Home/GetCities",
data: { id: $(obj).val() },
contentType: "application/json",
success: self.cities
});
}
}
ko.applyBindings(new CityModel());
thats all. But you have to bind your data into html elements.
Instead of using :
#Html.DropDownListFor(m => m.CityId, Cities, "Select City", new { id="ddlCity"})
You can use:
<select data-bind="options:cities,optionsValue:"Id",optionsText:"CityName",optionsCaption:"Select City""></select>
or you can mix razor and knockout:
#Html.DropDownListFor(m => m.CityId, Cities, "Select City", new { id="ddlCity",data_bind:"options:cities,optionsValue:\"Id\",optionsText:\"CityName\""})
One more thing you have to call GetCities when State changes, you can :
#Html.DropDownList("State", States, "Select State", new {data_bind:"event:\"change\":\"$root.GetCities\""})
Dont be scare with \"\" things this because " is an escape character and we have to say to razor i want to use " by using \ before it.
You can find more info about knockout :Knockout
And mixing with razor: Razor and Knockout
Ps: yes using knockout is suspend us from Razor and Mvc. You have to write another ViewModel . But like this situations ko is helpful. Mixing razor and knockout is another option for you.

DropDownList Change() doesn't seem to fire

So, I have been bashing my head against the desk for a day now. I know this may be a simple question, but the answer is eluding me. Help?
I have a DropDownList on a modal that is built from a partial view. I need to handle the .Change() on the DropDownList, pass the selected text from the DropDownList to a method in the controller that will then give me data to use in a ListBox. Below are the code snippets that my research led me to.
all other controls on the modal function perfectly.
Can anyone see where I am going wrong or maybe point me in the right direction?
ProcessController
// I have tried with [HttpGet], [HttpPost], and no attribute
public ActionResult RegionFilter(string regionName)
{
// Breakpoint here is never hit
var data = new List<object>();
var result = new JsonResult();
var vm = new PropertyModel();
vm.getProperties();
var propFilter = (from p in vm.Properties
where p.Region == regionName && p.Class == "Comparable"
select p).ToList();
var listItems = propFilter.ToDictionary(prop => prop.Id, prop => prop.Name);
data.Add(listItems);
result.Data = data;
return result;
}
Razor View
#section scripts{
#Scripts.Render("~/Scripts/ui_PropertyList.js")
}
...
<div id="wrapper1">
#using (Html.BeginForm())
{
...
<div id="fancyboxproperties" class="content">
#Html.Partial("PropertyList", Model)
</div>
...
<input type="submit" name="bt_Submit" value="#ViewBag.Title" class="button" />
}
</div>
Razor (Partial View "PropertyList.cshtml")
...
#{ var regions = (from r in Model.Properties
select r.Region).Distinct(); }
<div>
<label>Region Filter: </label>
<select id="ddl_Region" name="ddl_Region">
#foreach (var region in regions)
{
<option value=#region>#region</option>
}
</select>
</div>
// ListBox that needs to update after region is selected
<div>
#Html.ListBoxFor(x => x.Properties, Model.Properties.Where(p => p.Class == "Comparable")
.Select(p => new SelectListItem { Text = p.Name, Value = p.Id }),
new { Multiple = "multiple", Id = "lb_C" })
</div>
...
JavaScript (ui_PropertyList.js)
$(function () {
// other events that work perfectly
...
$("#ddl_Region").change(function () {
$.getJSON("/Process/RegionFilter/" + $("#ddl_Region > option:selected").attr("text"), updateProperties(data));
});
});
function updateProperties(data, status) {
$("#lb_C").html("");
for (var d in data) {
var addOption = new Option(data[d].Value, data[d].Name);
addOption.appendTo("#lb_C");
}
}

The callback function passed to your $.getJSON method is wrong. You need to pass a reference to the function, not to invoke it.
Try this:
$.getJSON("/Process/RegionFilter/" + $("#ddl_Region > option:selected").text(), updateProperties);
Also, in order to get the text of the selected drop-down option, you need to use the text() function:
$("#ddl_Region > option:selected").text()
See Documentation

Html.DropDownListFor and JavaScript Array

I've implemented Cascading Drop Down Lists on the Create View page of my MVC Asp.NET Application.
Unfortunately, I am having issues with selecting a value that is located in the JavaScript Array. I need to bind the selected value for the use of one of my controllers.
Right now my List populates, but I have no way to select it. Is there a way to move the counties[i] array from my JavaScript to the #Html.DropDownListFor() helper?
Thanks!
JavaScript:
<script src="#Url.Content("~/Scripts/jquery-1.10.2.min.js")"
type="text/javascript"></script>
<script language="javascript" type="text/javascript">
$(document).ready(function() {
$("#county").prop("disabled", true);
$("#StateLongName").change(function() {
if ($("#StateItems").val() != "Please select") {
var options = {};
options.url = "/County/GetCounties";
options.type = "POST";
options.data = JSON.stringify({ state: $("#StateLongName").val() });
options.dataType = "json";
options.contentType = "application/json";
options.success = function(counties) {
$("#county").empty();
for (var i = 0; i < counties.length; i++) {
$("#county").append("<option>" + counties[i] + "</option>");
}
$("#county").prop("disabled", false);
};
options.error = function() { alert("Error retrieving counties!"); };
$.ajax(options);
} else {
$("#county").empty();
$("#county").prop("disabled", true);
}
});
});
</script>
Controller:
//GET Counties for Cascading Dropdown List
public JsonResult GetCounties(string state)
{
var counties = db.countycigtaxes.Join(db.statecigtaxes,
cc => cc.stateid,
sc => sc.stateid,
(cc, sc) => new
{
cc,
sc
}).Where(co => co.sc.statefullname == state)
.Select(co => co.cc.countyfullname).ToList();
return Json(counties);
}
View Page:
<div class="form-group">
#Html.LabelFor(model => model.StateLongName, new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.DropDownListFor(m => m.StateLongName, Model.StateItems, "Please select")
#Html.ValidationMessageFor(model => model.StateLongName)
</div>
</div>
<div class="form-group">
#Html.LabelFor(model => model.CountyLongName, new { #class = "control-label col-md-2" })
<div class="col-md-10">
#*#Html.DropDownListFor(m => m.CountyLongName, )*#
<select id="county"></select>
#Html.ValidationMessageFor(model => model.CountyLongName)
</div>
</div>

I assume you mean the the selected value of the property CountyLongName is not posting back when you submit the form. You have commented out this line
#Html.DropDownListFor(m => m.CountyLongName, )
and used
<select id="county"></select>
If you want the manual version (I do not recommend this), then you need to add a name attribute that matches the property name so it can be bound by the ModelBinder
<select name="CountyLongName" id="county"></select>
But it is better to use the helper and pass it an empty SelectList
Html.DropDownListFor(m => m.CountyLongName, Model.CountryNames)
where Model.CountryNames is a property in you view model that is initialised to an empty SelectList
Note also options.type = "POST"; should be "GET" and the whole AJAX could be simplified to
$.get('#Url.Action("GetCounties","Country")', { state: $('#StateLongName').val() }, function(countries) {...
and theToList() is not required in the JsonResult method

This should set the option selected for you.
$("#county option[value='" + counties[index] + "']").attr("selected", "selected");