Question

I am creating a select list which is populated with enum values:

<%= Html.DropDownListFor(model => model.OrderStatus, new SelectList(Enum.GetValues(typeof(OrderStatus))))%>

I am now performing client-side validation to ensure that OrderStatus is set properly:

[DisplayName("Order Status"), EnsureOrderStatus("ID")]
public OrderStatus OrderStatus { get; set; }


public class EnsureOrderStatus : ValidationAttribute, IClientValidatable
    {
        private readonly string OrderIDPropertyName;

        public EnsureOrderStatus(string orderIDPropertyName)
        {
            OrderIDPropertyName = orderIDPropertyName;
        }

        protected override ValidationResult IsValid (object value, ValidationContext validationContext)
        {
            ValidationResult validationResult = ValidationResult.Success;

            var propertyTestedInfo = validationContext.ObjectType.GetProperty(OrderIDPropertyName);
            if (propertyTestedInfo == null)
            {
                validationResult = new ValidationResult(string.Format("Unknown property {0}", OrderIDPropertyName));
            }
            else
            {
                int orderID = (int)propertyTestedInfo.GetValue(validationContext.ObjectInstance, null);
                OrderStatus orderStatus = (OrderStatus)value;

                if (orderID == 0 && orderStatus != OrderStatus.Future)
                {
                    validationResult = new ValidationResult(string.Format("Order must have have an Order Status of Future when being created."));
                }
            }

            return validationResult;
        }

        public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
        {
            var rule = new ModelClientValidationRule
                {
                    ErrorMessage = ErrorMessage,
                    ValidationType = "ensureorderstatus"
                };

            rule.ValidationParameters["orderid"] = OrderIDPropertyName;
            yield return rule;
        }
    }

The value of ‘value’ inside of IsValid is always the first enum value of OrderStatus. I was wondering if there was other steps which need to be taken to ensure that the selected value of a DropDownList element updates properly.

UPDATED CODE:

//OrderDetailsModel:
[DisplayName("Order Status"), EnsureOrderStatus("ID")]
public OrderStatus OrderStatus { get; set; }
public List<OrderStatusModel> OrderStatusModels = new List<OrderStatusModel>();

public OrderDetailsModel()
{
    OrderStatusModels.Add(new OrderStatusModel { EnumStatus = OrderStatus.Active, StringStatus = "Active" });
    OrderStatusModels.Add(new OrderStatusModel { EnumStatus = OrderStatus.Completed, StringStatus = "Completed" });
    OrderStatusModels.Add(new OrderStatusModel { EnumStatus = OrderStatus.Future, StringStatus = "Future" });
}


<%= Html.DropDownListFor(model => model.OrderStatus, new SelectList(Model.OrderStatusModels, "StringStatus", "EnumStatus"))%>

Answer 1

I would rethink this.. personally. Trying to hack an enum into a SelectList will create more work than is required.

Simply, wrap this all in a ViewModel.. consider this:

public enum OrderStatus {
    NOT_SHIPPED,
    SHIPPED
}

public class ViewModel {
    public OrderStatus SelectedStatus { get; set; }
    public List<StatusViewModel> Models = new List<StatusViewModel>();
}

public class StatusViewModel {
    public string StringStatus { get; set; }
    public OrderStatus EnumStatus { get; set; }
}

Setup (perhaps in the controller.. or somewhere else) involves this:

ViewModel model = new ViewModel();

model.Models.Add(new StatusViewModel() { EnumStatus = OrderStatus.NOT_SHIPPED, StringStatus = "Not shipped" });
model.Models.Add(new StatusViewModel() { EnumStatus = OrderStatus.SHIPPED, StringStatus = "Shipped" });

return View(model);

..and your view is simply this:

@model Models.ViewModel
@Html.DropDownListFor(x => x.SelectedStatus, new SelectList(Model.Models, "StringStatus", "EnumStatus"))

Then, when your model comes in after being posted, the SelectedStatus is strongly typed OrderStatus enum:

public ActionResult Index(ViewModel model) {
    // model.SelectedStatus is an OrderStatus
}