Get .NET Enum Value Display Name

It is possible to specify the UI display name for enum members using the DisplayAttribute and its Name property.

using System.ComponentModel.DataAnnotations;

namespace MyNamespace;

public enum UserRole
{
    [Display(Name = "System admin")]
    SystemAdmin,
    Manager,
    [Display(Name = "Sales rep")]
    SalesRep,
    Technician
}

Some ASP.NET functions like HtmlHelper.GetEnumSelectList use the display name specified by the DisplayAttribute, but there is no built-in function to get the display name given an enum value. So I had to write this function.

using System.Collections.Concurrent;
using System.ComponentModel.DataAnnotations;
using System.Reflection;

namespace MyNamespace;

public static class EnumDisplayNameGetter
{
    private static readonly ConcurrentDictionary<Enum, string> _displayNameCache = new();

    public static string GetDisplayName(this Enum enumValue)
    {
        ArgumentNullException.ThrowIfNull(enumValue);

        return _displayNameCache.GetOrAdd(enumValue,
            ev =>
            {
                DisplayAttribute? displayAttribute = GetDisplayAttribute(ev);
                return displayAttribute?.GetName() ?? ev.ToString();
            }
        );
    }

    private static DisplayAttribute? GetDisplayAttribute(Enum enumValue)
    {
        Type enumType = enumValue.GetType();
        FieldInfo? fieldInfo = enumType.GetField(enumValue.ToString(),
            BindingFlags.Public | BindingFlags.Static);
        return fieldInfo?.GetCustomAttribute<DisplayAttribute>();
    }
}

The code above uses a ConcurrentDictionary to cache enum value display names when they are fetched for the first time. So the slow reflection code does not need to run more than once per application lifetime for each enum value. The extension method GetDisplayName() is thread-safe and can be used in multi-threaded applications like ASP.NET apps.

My implementation is derived from another implementation that I found in the OpenAPI.NET project.

The following code examples show how the GetDisplayName() extension method can be used.

string displayName = UserRole.SystemAdmin.GetDisplayName();

UserRole role = UserRole.SystemAdmin;
string displayName = role.GetDisplayName();

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Get .NET Enum Value Display Name