Use Enum Values in DropDownListFor - mysql

Question

This is my ViewModel:
public class EntityViewModel
{
[Required(ErrorMessage = "Title is required")]
[StringLength(255)]
[DisplayName("Title")]
public string Title { get; set; }
[Required(ErrorMessage = "Description is required")]
[DisplayName("Description")]
public string Description { get; set; }
[Required]
public DateTime StartTime { get; set; }
[Required]
public DateTime EndTime { get; set; }
[Required]
public Decimal InstantSellingPrice { get; set; }
public Nullable<Decimal> ShippingPrice { get; set; }
public Int64 Views { get; set; }
public Int32 UserId { get; set; }
public int RegionId { get; set; }
public short SelectCategoryId { get; set; }
public SelectList Categories { get; set; }
public IEnumerable<HttpPostedFileBase> Files { get; set; }
public Condition? Condition { get; set; }
}
public enum Condition
{
New=1,
Used=2
}
This is my Create Action in my Controller:
public ActionResult Create()
{
ViewBag.DropDownList = ReUzze.Helpers.EnumHelper.SelectListFor<Condition>();
var model = new ReUzze.Models.EntityViewModel
{
Categories = new SelectList(this.UnitOfWork.CategoryRepository.Get(), "Id", "Name")
};
return View(model);
}
In my Create View:
<div class="form-group">
#Html.LabelFor(model => model.Condition)
#Html.DropDownListFor(model => model.Condition, ViewBag.DropDownList as SelectList, null)
</div>
I am using the Enumhelper that you can find here.
But now I always get this error in my Create View on this rule:
#Html.DropDownListFor(model => model.Condition, ViewBag.DropDownList as SelectList, null)
The error:
Error 1 The call is ambiguous between the following methods or properties: 'System.Web.Mvc.Html.SelectExtensions.DropDownListFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression>, System.Collections.Generic.IEnumerable, string)' and 'System.Web.Mvc.Html.SelectExtensions.DropDownListFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression>, System.Collections.Generic.IEnumerable, System.Collections.Generic.IDictionary)' c:\Users\Niels\Documents\Visual Studio 2012\Projects\ReUzze\ReUzze\Views\Entity\Create.cshtml 57 30 ReUzze

Answer 1

I use code like this usually.
public static class Enums {
public static IList<SelectListItem> SelectListOf<TEnum>(bool empty = false)
{
var type = typeof(TEnum);
if (type.IsEnum)
{
var list = Enum.GetValues(type)
.Cast<TEnum>()
.OrderBy(x => x)
.Select(x => new SelectListItem { Text = GetDescription(x), Value = x.ToString() })
.ToList();
if (empty)
{
list.Insert(0, new SelectListItem());
}
return list;
}
return new List<SelectListItem>();
}
private static string GetDescription(object enumerator)
{
try
{
//get the enumerator type
Type type = enumerator.GetType();
//get the member info
MemberInfo[] memberInfo = type.GetMember(enumerator.ToString());
//if there is member information
if (memberInfo != null && memberInfo.Length > 0)
{
//we default to the first member info, as it's for the specific enum value
object[] attributes = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
//return the description if it's found
if (attributes != null && attributes.Length > 0)
return ((DescriptionAttribute)attributes[0]).Description;
}
//if there's no description, return the string value of the enum
return enumerator.ToString();
}
catch (Exception e)
{
return string.Empty;
}
}
}
Then you can use it like this:
Conditions = Enums.SelectListOf<Condition>();

Answer 2

Check out my blog post on this very subject.
http://jnye.co/Posts/4/creating-a-dropdown-list-from-an-enum-in-mvc-and-c%23
Here is an enum helper I use that turns an enum into a select list. Note: If the enum has a description (using the DescriptionAttribute) it will use that as its display text
public static class EnumHelper
{
// Get the value of the description attribute if the
// enum has one, otherwise use the value.
public static string GetDescription<TEnum>(this TEnum value)
{
var fi = value.GetType().GetField(value.ToString());
if (fi != null)
{
var attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attributes.Length > 0)
{
return attributes[0].Description;
}
}
return value.ToString();
}
/// <summary>
/// Build a select list for an enum
/// </summary>
public static SelectList SelectListFor<T>() where T : struct
{
Type t = typeof(T);
return !t.IsEnum ? null
: new SelectList(BuildSelectListItems(t), "Value", "Text");
}
/// <summary>
/// Build a select list for an enum with a particular value selected
/// </summary>
public static SelectList SelectListFor<T>(T selected) where T : struct
{
Type t = typeof(T);
return !t.IsEnum ? null
: new SelectList(BuildSelectListItems(t), "Value", "Text", selected.ToString());
}
private static IEnumerable<SelectListItem> BuildSelectListItems(Type t)
{
return Enum.GetValues(t)
.Cast<Enum>()
.Select(e => new SelectListItem { Value = e.ToString(), Text = e.GetDescription() });
}
}
Once you have this helper class in place you can do the following.
In your controller:
//If you don't have an enum value use the type
ViewBag.DropDownList = EnumHelper.SelectListFor<MyEnum>();
//If you do have an enum value use the value (the value will be marked as selected)
ViewBag.DropDownList = EnumHelper.SelectListFor(MyEnum.MyEnumValue);
In your View:
#Html.DropDownList("DropDownList")
#* OR *#
#Html.DropDownListFor(m => m.Property, ViewBag.DropDownList as SelectList, null)

Answer 3

if you want a quick workaround just for this one view you can do something like this. Although Khalid's approach is recommended.
<select id = 'myenumdropdown' class='something'>
#foreach(var item in Enum.GetValues(typeof('yourenumtype')))
{
<option value=item.ToHashCode()>item.ToString()</option>
}
</select>