从Description属性中获取Enum

< p > 可能的重复: < br > 通过描述属性查找枚举值 < / p >

我有一个泛型扩展方法，它从Enum中获取Description属性:

enum Animal
{
[Description("")]
NotSet = 0,


[Description("Giant Panda")]
GiantPanda = 1,


[Description("Lesser Spotted Anteater")]
LesserSpottedAnteater = 2
}


public static string GetDescription(this Enum value)
{
FieldInfo field = value.GetType().GetField(value.ToString());


DescriptionAttribute attribute
= Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute))
as DescriptionAttribute;


return attribute == null ? value.ToString() : attribute.Description;
}

所以我可以做…

string myAnimal = Animal.GiantPanda.GetDescription(); // = "Giant Panda"

现在，我试着在另一个方向上算出等效函数，就像……

Animal a = (Animal)Enum.GetValueFromDescription("Giant Panda", typeof(Animal));
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小开

您需要遍历Animal中的所有枚举值，并返回与所需描述匹配的值。

小开

你不能扩展Enum，因为它是一个静态类。您只能扩展类型的实例。考虑到这一点，你必须自己创建一个静态方法来完成这个任务;当与现有方法GetDescription结合使用时，以下方法应该有效:

public static class EnumHelper
{
public static T GetEnumFromString<T>(string value)
{
if (Enum.IsDefined(typeof(T), value))
{
return (T)Enum.Parse(typeof(T), value, true);
}
else
{
string[] enumNames = Enum.GetNames(typeof(T));
foreach (string enumName in enumNames)
{
object e = Enum.Parse(typeof(T), enumName);
if (value == GetDescription((Enum)e))
{
return (T)e;
}
}
}
throw new ArgumentException("The value '" + value
+ "' does not match a valid enum name or description.");
}
}

它的用法是这样的:

Animal giantPanda = EnumHelper.GetEnumFromString<Animal>("Giant Panda");
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最佳答案 
public static class EnumEx
{
public static T GetValueFromDescription<T>(string description) where T : Enum
{
foreach(var field in typeof(T).GetFields())
{
if (Attribute.GetCustomAttribute(field,
typeof(DescriptionAttribute)) is DescriptionAttribute attribute)
{
if (attribute.Description == description)
return (T)field.GetValue(null);
}
else
{
if (field.Name == description)
return (T)field.GetValue(null);
}
}


throw new ArgumentException("Not found.", nameof(description));
// Or return default(T);
}
}

用法:

var panda = EnumEx.GetValueFromDescription<Animal>("Giant Panda");
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应该是相当直截了当的，它只是你以前的方法相反;

public static int GetEnumFromDescription(string description, Type enumType)
{
foreach (var field in enumType.GetFields())
{
DescriptionAttribute attribute
= Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute))as DescriptionAttribute;
if(attribute == null)
continue;
if(attribute.Description == description)
{
return (int) field.GetValue(null);
}
}
return 0;
}

用法:

Console.WriteLine((Animal)GetEnumFromDescription("Giant Panda",typeof(Animal)));
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与其使用扩展方法，不如试试几个静态方法

public static class Utility
{
public static string GetDescriptionFromEnumValue(Enum value)
{
DescriptionAttribute attribute = value.GetType()
.GetField(value.ToString())
.GetCustomAttributes(typeof (DescriptionAttribute), false)
.SingleOrDefault() as DescriptionAttribute;
return attribute == null ? value.ToString() : attribute.Description;
}


public static T GetEnumValueFromDescription<T>(string description)
{
var type = typeof(T);
if (!type.IsEnum)
throw new ArgumentException();
FieldInfo[] fields = type.GetFields();
var field = fields
.SelectMany(f => f.GetCustomAttributes(
typeof(DescriptionAttribute), false), (
f, a) => new { Field = f, Att = a })
.Where(a => ((DescriptionAttribute)a.Att)
.Description == description).SingleOrDefault();
return field == null ? default(T) : (T)field.Field.GetRawConstantValue();
}
}

在这里使用

var result1 = Utility.GetDescriptionFromEnumValue(
Animal.GiantPanda);
var result2 = Utility.GetEnumValueFromDescription<Animal>(
"Lesser Spotted Anteater");
小开

这个解决方案工作得很好，除非您有一个Web服务。

您需要执行以下操作，因为Description属性不可序列化。

[DataContract]
public enum ControlSelectionType
{
[EnumMember(Value = "Not Applicable")]
NotApplicable = 1,
[EnumMember(Value = "Single Select Radio Buttons")]
SingleSelectRadioButtons = 2,
[EnumMember(Value = "Completely Different Display Text")]
SingleSelectDropDownList = 3,
}


public static string GetDescriptionFromEnumValue(Enum value)
{
EnumMemberAttribute attribute = value.GetType()
.GetField(value.ToString())
.GetCustomAttributes(typeof(EnumMemberAttribute), false)
.SingleOrDefault() as EnumMemberAttribute;
return attribute == null ? value.ToString() : attribute.Value;
}

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