Enum扩展方法调用Enum名称？

Question

我有下面的代码，运行良好。但是我需要使用扩展方法和它的Enum类型。

public class Dropdown
    {
        public Dropdown() { }
        public Dropdown(int id, string name)
        {
            Id = id;
            Name = name;
        }
        public Dropdown(string name)
        {
            Name = name;
        }
        public int Id { get; set; }
        public string StringId { get; set; }
        public string Name { get; set; }
    }

public enum AccidentTypeEnum
{
    [Display(Name = "Minor")]
    Minor = 0,
    [Display(Name = "Major")]
    Major = 1,
    [Display(Name = "Severe")]
    Severe = 2
}

可拓法

public static class EnumExtensions
    {
        public static List<Dropdown> ConvertToDropdown(this Enum mEnum)
        {
            var dropDownlist = new List<Dropdown>();

            var enumType = mEnum.GetType();

            var enumValuies = Enum.GetValues(enumType);
            foreach (var singleValue in enumValuies)
            {
                dropDownlist.Add(new Dropdown { Id = (int)singleValue, Name = singleValue.ToString() });

            }

            return dropDownlist;
       }
    }

问题：

如果我使用下面的行调用扩展方法，上面的代码运行良好

var TestAcident = AccidentTypeEnum.Major;
var resultDropdown = TestAcident.ConvertToDropdown();

但我怎么能像下面这样称呼它呢

 var resultDropdown = AccidentTypeEnum.ConvertToDropdown(); //<-- i need to use like this. but it not working 

Answer 1

你能做到的

List<AccidentTypeEnum> types = Utils<AccidentTypeEnum>.ConvertToDropdown();

这条路：

/// <summary>Pseudo extension class for enumerations</summary>
/// <typeparam name="TEnum">Enumeration type</typeparam>
public class Utils<TEnum> where TEnum : struct, IConvertible
{
    public static List<Dropdown> ConvertToDropdown()
    {
        var enumType = typeof(TEnum);

        return enumType.IsEnum
            ? enumType.GetEnumValues()
                .OfType<TEnum>()
                .Select(e => new Dropdown
                {
                    Id = Convert.ToInt32(Enum.Parse(enumType, e.ToString()) as Enum),
                    Name = GetDisplay(e)
                })
                .ToList()
            : throw new ArgumentException($"{enumType.Name} is not enum");
    }

    private static string GetDisplay<T>(T value)
    {
        var enumValueText = value.ToString();

        var displayAttribute = value
            .GetType()
            .GetField(enumValueText)
            .GetCustomAttributes(typeof(DisplayAttribute), false)
            .OfType<DisplayAttribute>()
            .FirstOrDefault();

        return displayAttribute == null ? enumValueText : displayAttribute.Description;
    }
}