如何从枚举成员获取说明属性值

Question

我有一个枚举类型

public enum DataType:int
    {   
        None = 0,
        [Description("A")]
        Alpha = 1,
        [Description("N")]
        Numeric,
        [Description("AN")]
        AlphaNumeric,
        [Description("D")]
        Date
    }

如何检索 Alpha 的描述属性值。

例如（理想）：DataType.Alpha.Attribute应该给出"A"

Answer 1

使用这个

private string GetEnumDescription(Enum value)
{
    // Get the Description attribute value for the enum value
    FieldInfo fi = value.GetType().GetField(value.ToString());
    DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
    if (attributes.Length > 0)
        return attributes[0].Description;
    else
        return value.ToString();
}

Answer 2

我有一个扩展方法来做到这一点：

public static string GetDescription(this Enum enumValue)
    {
        //Look for DescriptionAttributes on the enum field
        object[] attr = enumValue.GetType().GetField(enumValue.ToString())
            .GetCustomAttributes(typeof (DescriptionAttribute), false);
        if (attr.Length > 0) // a DescriptionAttribute exists; use it
            return ((DescriptionAttribute) attr[0]).Description;
        //The above code is all you need if you always use DescriptionAttributes;
        //If you don't, the below code will semi-intelligently 
        //"humanize" an UpperCamelCased Enum identifier
        string result = enumValue.ToString();
        //"FooBar" -> "Foo Bar"
        result = Regex.Replace(result, @"([a-z])([A-Z])", "$1 $2");
        //"Foo123" -> "Foo 123"
        result = Regex.Replace(result, @"([A-Za-z])([0-9])", "$1 $2");
        //"123Foo" -> "123 Foo"
        result = Regex.Replace(result, @"([0-9])([A-Za-z])", "$1 $2");
        //"FOOBar" -> "FOO Bar"
        result = Regex.Replace(result, @"(?<!^)(?<! )([A-Z][a-z])", " $1");
        return result;
    }

用法：

var description = DataType.Alpha.GetDescription(); //"A"
public enum TestEnums
{
   IAmAComplexABCEnumValue,
}
//"I Am A Complex ABC Enum Value"
var complexCamelCasedDescription = TestEnums.IAmAComplexABCEnumValue.GetDescription();

Answer 3

我创建了一个自定义泛型方法来从枚举中获取任何属性值。

public static class EnumHelper
{
    public static string GetAttributeValueByEnumValue<EnumType, AttributeType>(EnumType value, string attributeProperty = null)
        where EnumType : Enum
        where AttributeType : Attribute
    {
        var enumField = value.GetType().GetField(value.ToString());
        var enumAttributes = enumField?.GetCustomAttributes(typeof(AttributeType), false) as AttributeType[];
        if (enumAttributes == null || !enumAttributes.Any())
            throw new Exception($"Attribute [{typeof(AttributeType).Name}] not found in enum [{typeof(EnumType).Name}] type with value [{value.ToString()}]!");
        var enumAttribute = enumAttributes.First();
        
        var attributeValue = enumAttribute
            .GetType()
            ?.GetProperty(!string.IsNullOrEmpty(attributeProperty) ? attributeProperty : typeof(AttributeType).Name.Replace("Attribute", string.Empty))
            ?.GetValue(enumAttribute);
        if (attributeValue == null)
            throw new Exception("Error reading enum attribute value!");
        return attributeValue.ToString();
    }
}

要使用它，只需像下面这样调用它：

EnumHelper.GetAttributeValueByEnumValue<EnumLookup, DescriptionAttribute>(enumValue);

对于自定义枚举，您还可以提供属性属性名称，如下所示：

EnumHelper.GetAttributeValueByEnumValue<EnumLookup, TitleAttribute>(enumValue, "TitleName");

我希望它对你有所帮助:)