我想知道是否有可能获得枚举值的属性,而不是枚举本身?例如,假设我有以下枚举:
using System.ComponentModel; // for DescriptionAttribute
enum FunkyAttributesEnum
{
[Description("Name With Spaces1")]
NameWithoutSpaces1,
[Description("Name With Spaces2")]
NameWithoutSpaces2
}
我想要的是给定枚举类型,产生枚举字符串值及其描述的二元组。
价值很简单:
Array values = System.Enum.GetValues(typeof(FunkyAttributesEnum));
foreach (int value in values)
Tuple.Value = Enum.GetName(typeof(FunkyAttributesEnum), value);
但我如何获得描述属性的值,以填充Tuple.Desc?如果属性属于枚举本身,我可以想到如何做到这一点,但我不知道如何从枚举的值中获得它。
我这回答设置一个组合框从枚举属性,这是伟大的。
然后,我需要编写反向代码,以便从框中获得选择并返回正确类型的enum。
我还修改了代码,以处理缺少属性的情况
为了下一个人的利益,这是我的最终解决方案
public static class Program
{
static void Main(string[] args)
{
// display the description attribute from the enum
foreach (Colour type in (Colour[])Enum.GetValues(typeof(Colour)))
{
Console.WriteLine(EnumExtensions.ToName(type));
}
// Get the array from the description
string xStr = "Yellow";
Colour thisColour = EnumExtensions.FromName<Colour>(xStr);
Console.ReadLine();
}
public enum Colour
{
[Description("Colour Red")]
Red = 0,
[Description("Colour Green")]
Green = 1,
[Description("Colour Blue")]
Blue = 2,
Yellow = 3
}
}
public static class EnumExtensions
{
// This extension method is broken out so you can use a similar pattern with
// other MetaData elements in the future. This is your base method for each.
public static T GetAttribute<T>(this Enum value) where T : Attribute
{
var type = value.GetType();
var memberInfo = type.GetMember(value.ToString());
var attributes = memberInfo[0].GetCustomAttributes(typeof(T), false);
// check if no attributes have been specified.
if (((Array)attributes).Length > 0)
{
return (T)attributes[0];
}
else
{
return null;
}
}
// This method creates a specific call to the above method, requesting the
// Description MetaData attribute.
public static string ToName(this Enum value)
{
var attribute = value.GetAttribute<DescriptionAttribute>();
return attribute == null ? value.ToString() : attribute.Description;
}
/// <summary>
/// Find the enum from the description attribute.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="desc"></param>
/// <returns></returns>
public static T FromName<T>(this string desc) where T : struct
{
string attr;
Boolean found = false;
T result = (T)Enum.GetValues(typeof(T)).GetValue(0);
foreach (object enumVal in Enum.GetValues(typeof(T)))
{
attr = ((Enum)enumVal).ToName();
if (attr == desc)
{
result = (T)enumVal;
found = true;
break;
}
}
if (!found)
{
throw new Exception();
}
return result;
}
}
}
或者,你可以这样做:
Dictionary<FunkyAttributesEnum, string> description = new Dictionary<FunkyAttributesEnum, string>()
{
{ FunkyAttributesEnum.NameWithoutSpaces1, "Name With Spaces1" },
{ FunkyAttributesEnum.NameWithoutSpaces2, "Name With Spaces2" },
};
并使用以下语句获取描述:
string s = description[FunkyAttributesEnum.NameWithoutSpaces1];
在我看来,这是一种更有效的方式去做你想要完成的事情,因为不需要思考。
从enum中获取字典。
public static IDictionary<string, int> ToDictionary(this Type enumType)
{
return Enum.GetValues(enumType)
.Cast<object>()
.ToDictionary(v => ((Enum)v).ToEnumDescription(), k => (int)k);
}
现在把它叫做…
var dic = typeof(ActivityType).ToDictionary();
枚举描述Ext方法
public static string ToEnumDescription(this Enum en) //ext method
{
Type type = en.GetType();
MemberInfo[] memInfo = type.GetMember(en.ToString());
if (memInfo != null && memInfo.Length > 0)
{
object[] attrs = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attrs != null && attrs.Length > 0)
return ((DescriptionAttribute)attrs[0]).Description;
}
return en.ToString();
}
public enum ActivityType
{
[Description("Drip Plan Email")]
DripPlanEmail = 1,
[Description("Modification")]
Modification = 2,
[Description("View")]
View = 3,
[Description("E-Alert Sent")]
EAlertSent = 4,
[Description("E-Alert View")]
EAlertView = 5
}
这是一个使用lambda进行选择的通用实现
public static Expected GetAttributeValue<T, Expected>(this Enum enumeration, Func<T, Expected> expression)
where T : Attribute
{
T attribute =
enumeration
.GetType()
.GetMember(enumeration.ToString())
.Where(member => member.MemberType == MemberTypes.Field)
.FirstOrDefault()
.GetCustomAttributes(typeof(T), false)
.Cast<T>()
.SingleOrDefault();
if (attribute == null)
return default(Expected);
return expression(attribute);
}
这样叫它:
string description = targetLevel.GetAttributeValue<DescriptionAttribute, string>(x => x.Description);
模型
我们用这个模型来充实我们的价值观
public class MemberTypeModel : IDto
{
public string MemberAttributeName { get; set; }
public string MemberName { get; set; }
public int MemberValue { get; set; }
}
Enum
我们的目标是枚举
public enum MemberType
{
[FieldText("Yönetim Kurul Üyesi")]
BoardManager = 0,
[FieldText("Temsilci")]
Representative = 1,
[FieldText("Üye")]
Member = 2
}
辅助方法
我们将使用helper方法来获取自定义属性对象
public T GetMemberCustomText<T>(MemberType memberType) where T : Attribute
{
var enumType = memberType.GetType();
var name = Enum.GetName(enumType, memberType);
return enumType.GetField(name).GetCustomAttributes(false).OfType<T>().SingleOrDefault();
}
Get方法
首先,我们提取枚举值并将它们转换为枚举类型。然后,通过Linq选择查询我们知道;
MemberAttributeName字段与helper方法,
带有Enum的MemberName字段。GetName方法,
将MemberValue字段转换为int类型,
我们把它填好,然后变成一个清单。
public List<MemberTypeModel> GetMemberTypes()
{
var memberTypes = Enum.GetValues(typeof(MemberType))
.Cast<MemberType>()
.Select(et => new MemberTypeModel
{
MemberAttributeName = GetMemberCustomText<FieldText>(et).Text,
MemberName = Enum.GetName(et.GetType(), et),
MemberValue = (int)et
}).ToList();
return memberTypes;
}
流利的一句话…
这里我使用的DisplayAttribute包含Name和Description属性。
public static DisplayAttribute GetDisplayAttributesFrom(this Enum enumValue, Type enumType)
{
return enumType.GetMember(enumValue.ToString())
.First()
.GetCustomAttribute<DisplayAttribute>();
}
例子
public enum ModesOfTransport
{
[Display(Name = "Driving", Description = "Driving a car")] Land,
[Display(Name = "Flying", Description = "Flying on a plane")] Air,
[Display(Name = "Sea cruise", Description = "Cruising on a dinghy")] Sea
}
void Main()
{
ModesOfTransport TransportMode = ModesOfTransport.Sea;
DisplayAttribute metadata = TransportMode.GetDisplayAttributesFrom(typeof(ModesOfTransport));
Console.WriteLine("Name: {0} \nDescription: {1}", metadata.Name, metadata.Description);
}
输出
Name: Sea cruise
Description: Cruising on a dinghy