How can I convert an enumeration into a List<SelectListItem>?

i have an asp.net-mvc webpage and i want to show a dropdown list that is based off an enum. I want to show the text of each enum item and the id being the int value that the enum is associated with. Is there any elegant way of doing this conversion?

You can use LINQ:

Enum.GetValues(typeof(MyEnum)).Cast<MyEnum>().Select(v => new SelectListItem {
    Text = v.ToString(),
    Value = ((int)v).ToString()
}).ToList();

Since MVC 5.1, the most elegant way would be to use EnumDropDownListFor method of Html helper if you need to populate select options in your view:

@Html.EnumDropDownListFor(m => m.MyEnumProperty,new { @class="form-control"})

or GetSelectList method of EnumHelper in your controller:

var enumList = EnumHelper.GetSelectList(typeof (MyEnum));

I did this using a static method that I could reuse.

public static IEnumerable<SelectListItem> EnumToSelectList<T>()
{
    return (Enum.GetValues(typeof(T)).Cast<T>().Select(
        e => new SelectListItem() { Text = e.ToString(), Value = e.ToString() })).ToList();
}

I used GetEnumSelectList from the Html Helper class

<select asp-for="MyProperty" class="form-control" asp-items="@Html.GetEnumSelectList<MyEnum>()" ></select>

Now I used Tuple<string, string> but you can convert this to use anything:

var values = Enum.GetValues(typeof(DayOfWeek))
    .Cast<DayOfWeek>()
    .Select(d => Tuple.Create(((int)d).ToString(), d.ToString()))
    .ToList()

You can use Enum.GetNames() to get a string array containing the names of the enum items. If your item names are user friendly, then this is probably good enough. Otherwise, you could create your own GetName() method that would return a nice name for each item.

OR - if the enum will never (or rarely) change, you could just create a method that directly adds hard-coded items to your dropdown. This is probably more efficient (if that is important to you).

It's super easy with my extension method. Which also allows you to provide options like adding placeholder, grouping and disabling certain values or groups. Give it a try.

enum Color
{		
	Blue,
	[Category("Light")]
	[DisplayName("Light Blue")]
	LBlue,
	[Category("Dark")]
	[DisplayName("Dark Blue")]
	DBlue,
	Red,
	[Category("Dark")]
	[DisplayName("Dark Red")]
	DRed,
	[Category("Light")]
	[DisplayName("Light Red")]
	LRed,
	Green,
	[Category("Dark")]
	[DisplayName("Dark Green")]
	DGreen,
	[Category("Light")]
	[DisplayName("Light Green")]
	LGreen	
}

var list = typeof(Color).ToSelectList();

//or with custom options
var list = typeof(Color).ToSelectList(new SelectListOptions { Placeholder = "Please Select A Color"});

Here's the link to the github repo.

In the Asp.Net Core, just use:

<select asp-for="MyEnum" asp-items="Html.GetEnumSelectList(typeof(MyEnum))"></select>

Or

Create Helper

public static class EnumHelper
{
    public static IEnumerable<SelectListItem> GetEnumSelectList<TEnum>(bool isNullable = false)
        where TEnum : struct
    {
        IList<SelectListItem> selectLists = Enum.GetValues(typeof(TEnum)).Cast<TEnum>().Select(c => new SelectListItem()
        {
            Text = GetDisplayName(c),
            Value = c.ToString()
        }).ToList();

        if (isNullable)
        {
            selectLists.Add(new SelectListItem());
        }

        return selectLists.OrderBy(c => c.Value);
    }

    public static string GetDisplayName<TEnum>(TEnum enumVal)
    {
        DisplayAttribute attr = GetAttribute<DisplayAttribute>(enumVal);

        if (attr != null)
        {
            return attr.Name;
        }

        return enumVal?.ToString() ?? string.Empty;
    }

    public static TEnum GetAttribute<TEnum>(object enumVal) where TEnum : Attribute
    {
        if (enumVal == null)
        {
            return default;
        }

        Type type = enumVal.GetType();
        MemberInfo[] memInfo = type.GetMember(enumVal.ToString());

        if (memInfo.Length == 0)
        {
            return null;
        }

        object[] attributes = memInfo[0].GetCustomAttributes(typeof(TEnum), false);
        return attributes.Length > 0 ? (TEnum)attributes[0] : null;
    }
}

To use

@using MyClass.Helpers;
    
<select asp-for="MyEnum" asp-items="EnumHelper.GetEnumSelectList<MyEnum>(true)">/select>