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。
我在这里合并了几个答案，以创建一个更具可扩展性的解决方案。我提供这些只是为了将来对其他人有所帮助。原文在此。
using System;
using System.ComponentModel;
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);
return attributes.Length > 0
? (T)attributes[0]
: 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;
}
}
这个解决方案在Enum上创建一对扩展方法。第一种方法允许您使用反射来检索与您的值相关的任何属性。第二个调用检索DescriptionAttribute并返回它的Description值。
例如，考虑使用System中的DescriptionAttribute属性。ComponentModel
using System.ComponentModel;
public enum Days {
[Description("Sunday")]
Sun,
[Description("Monday")]
Mon,
[Description("Tuesday")]
Tue,
[Description("Wednesday")]
Wed,
[Description("Thursday")]
Thu,
[Description("Friday")]
Fri,
[Description("Saturday")]
Sat
}
要使用上面的扩展方法，你现在只需调用下面的方法:
Console.WriteLine(Days.Mon.ToName());
or
var day = Days.Mon;
Console.WriteLine(day.ToName());
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;
}
}
}
添加我的解决方案的Net Framework和NetCore。
我在我的Net Framework实现中使用了这个:
public static class EnumerationExtension
{
public static string Description( this Enum value )
{
// get attributes
var field = value.GetType().GetField( value.ToString() );
var attributes = field.GetCustomAttributes( typeof( DescriptionAttribute ), false );
// return description
return attributes.Any() ? ( (DescriptionAttribute)attributes.ElementAt( 0 ) ).Description : "Description Not Found";
}
}
这并不适用于NetCore，所以我修改了它，这样做:
public static class EnumerationExtension
{
public static string Description( this Enum value )
{
// get attributes
var field = value.GetType().GetField( value.ToString() );
var attributes = field.GetCustomAttributes( false );
// Description is in a hidden Attribute class called DisplayAttribute
// Not to be confused with DisplayNameAttribute
dynamic displayAttribute = null;
if (attributes.Any())
{
displayAttribute = attributes.ElementAt( 0 );
}
// return description
return displayAttribute?.Description ?? "Description Not Found";
}
}
枚举的例子:
public enum ExportTypes
{
[Display( Name = "csv", Description = "text/csv" )]
CSV = 0
}
使用任何静态添加:
var myDescription = myEnum.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;
}
