关于c＃：从Description属性获取Enum

Get Enum from Description attribute

本问题已经有最佳答案，请猛点这里访问。

Possible Duplicate:
Finding an enum value by its Description Attribute

我有一个从Enum获取Description属性的通用扩展方法：

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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…

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

现在，我试着从另一个方向，求出等价函数，比如…

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

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public static class EnumEx
{
public static T GetValueFromDescription<T>(string description)
{
var type = typeof(T);
if(!type.IsEnum) throw new InvalidOperationException();
foreach(var field in type.GetFields())
{
var attribute = Attribute.GetCustomAttribute(field,
typeof(DescriptionAttribute)) as DescriptionAttribute;
if(attribute != null)
{
if(attribute.Description == description)
return (T)field.GetValue(null);
}
else
{
if(field.Name == description)
return (T)field.GetValue(null);
}
}
throw new ArgumentException("Not found.","description");
// or return default(T);
}
}

用途：

1	var panda = EnumEx.GetValueFromDescription<Animal>("Giant Panda");

相关讨论

而不是扩展方法，只需尝试两个静态方法

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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

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

相关讨论

除非您有Web服务，否则该解决方案工作得很好。

您需要执行以下操作，因为描述属性不可序列化。

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[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;
}

相关讨论

应该是非常简单的，这与你以前的方法正好相反；

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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;
}

用途：

1	Console.WriteLine((Animal)GetEnumFromDescription("Giant Panda",typeof(Animal)));

不能扩展Enum，因为它是一个静态类。只能扩展类型的实例。考虑到这一点，您必须自己创建一个静态方法来实现这一点；当与现有方法GetDescription结合时，以下方法应该有效：

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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：

1	Animal giantPanda = EnumHelper.GetEnumFromString<Animal>("Giant Panda");

相关讨论

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。

相关讨论