Problem with getting selected OBJECT from dropdownlist

asp.netdrop-down-menu

I have a problem with getting selected objectfrom my list.

I bind collection of users to dropdownlist by:

 ddlContractors.DataSource = service.GetAllUsers();
                ddlContractors.DataTextField = "Name";
                ddlContractors.DataValueField = "Id";
                ddlContractors.DataBind();

It's working.
But when I try getting selected object by:

var user = (User)ddlContractors.SelectedItem;

I get:

    (User)ddlContractors.SelectedItem   Cannot convert type 'System.Web.UI.WebControls.ListItem' to 'GWDSite.GWDService.User'

How can I get object user from dropdownlist ? I can change type of my list control if it is necessary

Best Answer

The value field in the dropdown list is the field "Id" not the User object. so 'SelectedItem' is returning the "Id" value -- not the object. You can use that Id to lookup the User object (from session or cache or wherever you can keep it)

Related Solutions

C# – How to bind an Enum to a DropDownList control in ASP.NET

I probably wouldn't bind the data as it's an enum, and it won't change after compile time (unless I'm having one of those stoopid moments).

Better just to iterate through the enum:

Dim itemValues As Array = System.Enum.GetValues(GetType(Response))
Dim itemNames As Array = System.Enum.GetNames(GetType(Response))

For i As Integer = 0 To itemNames.Length - 1
    Dim item As New ListItem(itemNames(i), itemValues(i))
    dropdownlist.Items.Add(item)
Next

Or the same in C#

Array itemValues = System.Enum.GetValues(typeof(Response));
Array itemNames = System.Enum.GetNames(typeof(Response));

for (int i = 0; i <= itemNames.Length - 1 ; i++) {
    ListItem item = new ListItem(itemNames[i], itemValues[i]);
    dropdownlist.Items.Add(item);
}

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common