DropDownListFor - does not select "Selected" value

Question

Another one of these questions regarding DropDownListFor not selecting the "Selected" value. Here is code:

Model:

public class CreateEditAccountModel
{
    [Required]
    [Display(Name = "Permission")]
    public int PermissionId { get; set; }
    public IEnumerable<SelectListItem> Permissions { get; set; }
}

Controller:

[HttpGet]
[Authorize]
public ActionResult EditAccount(int id)
{
    CreateEditAccountModel model = new CreateEditAccountModel();
    model.Permissions = PermissionsAll();
    return View("CreateEditAccount", model);
}

At this point if I put a break point on return line, the model.Permissions contains proper IEnumerable<SelectListItem> object with multiple items and only one, that has Selected = true.

View:

@using (Html.BeginForm())
{
    @Html.DropDownListFor(m => m.PermissionId, Model.Permissions)
}

Renders:

<select id="PermissionId" name="PermissionId">
    <option value="">-- Select --</option>
    <option value="1">Permission one</option>
    <option value="2">Permission two</option>
</select>

For some reason there is no selected attribute on any of the options and first option is selected.

Any help is appreciated.

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UPDATE

It appears it has something to do with this article. To summarize the solution of this article, I need to make sure that the property name (first argument of @html.DropDownList) does not match any existing properties of the model. Can anybody explain why this is the case?

It renders drop down correctly when I write in the view something like this:

@Html.DropDownList("PermissionIdNotMatching", Model.Permissions)

However, it does not make any logical sense to do it since I actually want binder to be able to match the name of the select element to the model property. Otherwise I'd have to manually grab the value like this: Request.Form["PermissionIdNotMatching"];

Anybody have any thoughts?

---

SOLUTION

See accepted answer and the first comment to it.

Answer 1

Ok, let's discuss about your example, when PermissionId was int. You posted model of type CreateEditAccountModel to view. When you created this model, PermissionId equal 0 (default value of int). And DropDownListFor in view get this value. Therefore you had no selected values. When you used string type, default value of PermissionId was null, therefore `DropDownListFor taken default value of SelectList.

In this case it's better to use int? or Nullable<int> type for PermissionId.