EnumHelpers.cs

EnumHelpers.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Reflection;

namespace Helpers
{
    public class EnumHelpers
    {
        public static string GetEnumDescription(Enum value)
        {
            FieldInfo fi = value.GetType().GetField(value.ToString());
            DescriptionAttribute[] attributes = fi.GetCustomAttributes(typeof(DescriptionAttribute), false) as DescriptionAttribute[];
            return (attributes != null && attributes.Length > 0) ? attributes[0].Description : value.ToString();
        }

        public static string GetDescription(Enum enumValue)
        {
            string output = null;
            Type type = enumValue.GetType();
            FieldInfo fi = type.GetField(enumValue.ToString());
            var attrs = fi.GetCustomAttributes(typeof(DescriptionAttribute), false) as DescriptionAttribute[];
            if (attrs.Length > 0) output = attrs[0].Description;
            return (!string.IsNullOrWhiteSpace(output)) ? output : enumValue.ToString();
        }

        public static T GetEnumValue<T>(int id)
        {
            Type enumType = typeof(T);

            // Can't use type constraints on value types, so have to do check like this
            if (enumType.BaseType != typeof(Enum))
                throw new ArgumentException("T must be of type System.Enum");

            if (Enum.IsDefined(enumType, id))
                return (T)Enum.ToObject(enumType, id);
            else if (Enum.IsDefined(enumType, id.ToString()))
                return (T)Enum.Parse(enumType, id.ToString());
            else
                throw new ArgumentException(string.Format("Parameter id \"{0}\" is not defined in {1}", id.ToString(), enumType));
        }

        public static T GetEnumValue<T>(string value)
        {
            Type enumType = typeof(T);
            int attemptedValue = 0;

            // Can't use type constraints on value types, so have to do check like this
            if (enumType.BaseType != typeof(Enum))
                throw new ArgumentException("T must be of type System.Enum");

            if (int.TryParse(value, out attemptedValue) && Enum.IsDefined(enumType, attemptedValue))
                return (T)Enum.Parse(enumType, value);
            else if (Enum.IsDefined(enumType, value))
                return (T)Enum.Parse(enumType, value);
            else
                throw new ArgumentException(string.Format("Parameter for value \"{0}\" is not defined in {1}", value, enumType));
        }

        public static IDictionary<T, string> GetEnumValuesWithDescription<T>(Type type) where T : struct, IConvertible
        {
            if (!type.IsEnum)
                throw new ArgumentException("T must be an enumerated type");

            return type.GetEnumValues().OfType<T>().ToDictionary(key => key, val => GetDescription(val as Enum));
        }
    }
}