@using System.ComponentModel.DataAnnotations
@using System.Reflection

<TelerikForm Model="@data" Width="300px">
    <FormValidation>
        <DataAnnotationsValidator />
    </FormValidation>
    <FormItems>
        <FormItem>
            <Template>
                <label for="address">Address : @data.Address</label>
                <TelerikTextBox Id="address" @bind-Value ="@data.Address"></TelerikTextBox>
                <TelerikValidationMessage For="@(() => data.Address)"></TelerikValidationMessage>
            </Template>
        </FormItem>
        <FormItem>
            <Template>
                <label for="delivery">Delivery: @data.MailOption</label>
                <TelerikDropDownList Data="@myDdlData"
                                     TextField="MyTextField"
                                     ValueField="MyValueField" @bind-Value="@data.MailOption"
                                     Id="delivery">
                </TelerikDropDownList>
                <TelerikValidationMessage For="@(() => data.MailOption)"></TelerikValidationMessage>
            </Template>
        </FormItem>
    </FormItems>
</TelerikForm>


@code {
    //form model
    public MyModel data = new MyModel();

    public class MyModel
    {
        [Required(ErrorMessage = "Address must be provided.")]
        public string Address { get; set; }

        [Required(ErrorMessage = "Select delivery option.")]
        public DeliveryMailOptions MailOption { get; set; }
    }

    //dropdownlist model
    public class EnumDdlModel
    {
        public DeliveryMailOptions MyValueField { get; set; }
        public string MyTextField { get; set; }
    }

    List<EnumDdlModel> myDdlData { get; set; } = new List<EnumDdlModel>();

    protected override void OnInitialized()
    {
        //prepare instances of the model from the list of enum values and a desired string representation for the user
        foreach (DeliveryMailOptions item in Enum.GetValues(typeof(DeliveryMailOptions)))
        {

            myDdlData.Add(new EnumDdlModel {MyTextField = GetDisplayName(item), MyValueField = item });
        }

        base.OnInitialized();
    }

    public enum DeliveryMailOptions
    {
        Regular,
        [Display(Name = "FedEx Priority")]
        FedExPriority,
        [Display(Name = "FedEx Two-Day")]
        FedExTwoDay
    }

    //custom method to check if a Display Attribute exists and return its Name property,
    //otherwise fallback to the enum’s member name instead.
    public string GetDisplayName(Enum val)
    {
        return val.GetType()
                  .GetMember(val.ToString())
                  .FirstOrDefault()
                  ?.GetCustomAttribute<DisplayAttribute>(false)
                  ?.Name
                  ?? val.ToString();
    }
}

Regards,
Nadezhda Tacheva
Progress Telerik