When you pass an object like this:

new SelectList(Model, "Code", "Name", 0)

you are saying: the Source (Model) and Key ("Code") the Text ("Name") and the selected value 0. You probably do not have a 0 value in your source for Code property, so the HTML Helper will select the first element to pass the real selectedValue to this control.

Make sure that you have trim the selected value before you assigning.

//Model

public class SelectType
{
public string Text { get; set; }
public string Value { get; set; }
}

//Controller

var types = new List<SelectType>();
types.Add(new SelectType() { Value =  0, Text = "Select a Type" });
types.Add(new SelectType() { Value =  1, Text = "Family Trust" });
types.Add(new SelectType() { Value =  2, Text = "Unit Trust"});
ViewBag.PartialTypes = types;

//View

@Html.DropDownListFor(m => m.PartialType, new SelectList(ViewBag.PartialTypes, "Value", "Text"), new { id = "Type" })

Your code has some conceptual issues:

First,

@Html.DropDownListFor(n => n.OrderTemplates, new SelectList(Model.OrderTemplates, "OrderTemplateId", "OrderTemplateName", 1), "Please select an order template")

When using DropDownListFor, the first parameter is the property where your selected value is stored once you submit the form. So, in your case, you should have a SelectedOrderId as part of your model or something like that, in order to use it in this way:

@Html.DropDownListFor(n => n.SelectedOrderId, new SelectList(Model.OrderTemplates, "OrderTemplateId", "OrderTemplateName", 1), "Please select an order template")

Second,

Aside from using ViewBag, that is not wrong but there are better ways (put that information in the ViewModel instead), there is a "little bug" (or an unspected behavior) when your ViewBag property, where you are holding the SelectList, is the same name of the property where you put the selected value. To avoid this, just use another name when naming the property holding the list of items.

Some code I would use if I were you to avoid this issues and write better MVC code:

Viewmodel:

public class MyViewModel{
public int SelectedOrderId {get; set;}
public SelectList OrderTemplates {get; set;}


// Other properties you need in your view
}

Controller:

public ActionResult MyAction(){
var model = new MyViewModel();
model.OrderTemplates = new SelectList(db.OrderTemplates, "OrderTemplateId", "OrderTemplateName", 1);
//Other initialization code


return View(model);
}

In your View:

@Html.DropDownListFor(n => n.SelectedOrderId, Model.OrderTemplates, "Please select an order template")

You should forget the class

SelectList

Use this in your Controller:

var customerTypes = new[]
{
new SelectListItem(){Value = "all", Text= "All"},
new SelectListItem(){Value = "business", Text= "Business"},
new SelectListItem(){Value = "private", Text= "Private"},
};

Select the value:

var selectedCustomerType = customerTypes.FirstOrDefault(d => d.Value == "private");
if (selectedCustomerType != null)
selectedCustomerType.Selected = true;

Add the list to the ViewData:

ViewBag.CustomerTypes = customerTypes;

Use this in your View:

@Html.DropDownList("SectionType", (SelectListItem[])ViewBag.CustomerTypes)

-

More information at: http://www.asp.net/mvc/overview/older-versions/working-with-the-dropdownlist-box-and-jquery/using-the-dropdownlist-helper-with-aspnet-mvc

For me was not working so worked this way:

Controller:

int selectedId = 1;


ViewBag.ItemsSelect = new SelectList(db.Items, "ItemId", "ItemName",selectedId);

View:

@Html.DropDownListFor(m => m.ItemId,(SelectList)ViewBag.ItemsSelect)

JQuery:

$("document").ready(function () {
$('#ItemId').val('@Model.ItemId');
});

Add the Controller Section

  ViewBag.Orders= new SelectList(db.Orders, "Id", "business", paramid);

Add the Html Section

   @Html.DropDownList("Orders", null)

A simple method

For me general solution :)

@{
var selectedCity = Model.Cities.Where(k => k.Id == Model.Addres.CityId).FirstOrDefault();
if (selectedCity != null)
{
@Html.DropDownListFor(model => model.Addres.CityId, new SelectList(Model.Cities, "Id", "Name", selectedCity.Id), new { @class = "form-control" })
}
else
{
@Html.DropDownListFor(model => model.Cities, new SelectList(Model.Cities, "Id", "Name", "1"), new { @class = "form-control" })
}
}

If you know what will be in the view, you can also set the default value from Controller as well rather then set up it into the view/cshtml file. No need to set default value from HTML side.

In the Controller file.

commission.TypeofCommission = 1;
return View(commission);

In the .cshtml file.

@Html.DropDownListFor(row => row.TypeofCommission, new SelectList(Model.commissionTypeModelList, "type", "typeName"), "--Select--")

Linq to Dropdown with empty item, selected item (works 100%)
(Strongly Typed,Chances for error minimum) Any model changes will be reflected in the binding

Controller

public ActionResult ManageSurveyGroup()
{
tbl_Survey sur = new tbl_Survey();
sur.Survey_Est = "3";


return View(sur);
}

View

        @{




//Step One : Getting all the list
var CompEstdList = (from ComType in db.tbl_CompEstdt orderby ComType.Comp_EstdYr select ComType).ToList();


//Step Two  : Adding a no Value item **
CompEstdList.Insert(0, new eDurar.Models.tbl_CompEstdt { Comp_Estdid = 0, Comp_EstdYr = "--Select Company Type--" });


//Step Three : Setting selected Value if value is present
var selListEstd= CompEstdList.Select(s => new SelectListItem { Text = s.Comp_EstdYr, Value = s.Comp_Estdid.ToString() });


}
@Html.DropDownListFor(model => model.Survey_Est, selListEstd)
@Html.ValidationMessageFor(model => model.Survey_Est)

This method for binding data also possible

var selList = CompTypeList.Select(s => new SelectListItem { Text = s.CompTyp_Name, Value = s.CompTyp_Id.ToString(), Selected = s.CompTyp_Id == 3 ? true : false });

I know this is not really an answer to the question, but I was looking for a way to initialize the DropDownList from a list on the fly in the view when I kept stumbling upon this post.

My mistake was that I tried to create a SelectList from dictionary like this:

//wrong!
@Html.DropDownListFor(m => m.Locality, new SelectList(new Dictionary<string, string>() { { Model.Locality, Model.Locality_text } }, Model.Locality, ...

I then went digging in the official msdn doc, and found that DropDownListFor doesn't necessarily require a SelectList, but rather an IEnumerable<SelectListItem>:

//right
@Html.DropDownListFor(m => m.Locality, new List<SelectListItem>() { new SelectListItem() { Value = Model.Locality, Text = Model.Locality_text, Selected = true } }, Model.Locality, new { @class = "form-control select2ddl" })

In my case I can probably also omit the Model.Locality as selected item, since its a) the only item and b) it already says it in the SelectListItem.Selected property.

Just in case you're wondering, the datasource is an AJAX page, that gets dynamically loaded using the SelectWoo/Select2 control.

public byte UserType
public string SelectUserType

You need to get one and set different one. Selected value can not be the same item that you are about to set.

@Html.DropDownListFor(p => p.SelectUserType, new SelectList(~~UserTypeNames, "Key", "Value",UserType))

I use Enum dictionary for my list, that's why there is "key", "value" pair.

I had a similar issue, I was using the ViewBag and Element name as same. (Typing mistake)

This is CSS issues. I don't know why @Html.DropDownListFor in Bootstrap 4 doest work. Surely this is class design problem. Anyways the work arround is, if your Dropdown input box has CSS Padding: #px, # px; element then disable it. Hope this will work.