C# 从枚举属性获取枚举
我有C# 从枚举属性获取枚举,c#,.net,enums,attributes,custom-attributes,C#,.net,Enums,Attributes,Custom Attributes,我有 public enum Als { [StringValue("Beantwoord")] Beantwoord = 0, [StringValue("Niet beantwoord")] NietBeantwoord = 1, [StringValue("Geselecteerd")] Geselecteerd = 2, [StringValue("Niet geselecteerd")] NietGeselecteerd = 3, } 与 我想把我从
public enum Als
{
[StringValue("Beantwoord")] Beantwoord = 0,
[StringValue("Niet beantwoord")] NietBeantwoord = 1,
[StringValue("Geselecteerd")] Geselecteerd = 2,
[StringValue("Niet geselecteerd")] NietGeselecteerd = 3,
}
int i = (int)(Als)Enum.Parse(typeof(Als), (string)cboAls.SelectedValue); //<- WRONG
inti=（int）（Als）Enum.Parse（typeof（Als），（string）cboAls.SelectedValue）// 这里有一个助手方法，它应该为您指明正确的方向
protected Als GetEnumByStringValueAttribute(string value)
{
Type enumType = typeof(Als);
foreach (Enum val in Enum.GetValues(enumType))
{
FieldInfo fi = enumType.GetField(val.ToString());
StringValueAttribute[] attributes = (StringValueAttribute[])fi.GetCustomAttributes(
typeof(StringValueAttribute), false);
StringValueAttribute attr = attributes[0];
if (attr.Value == value)
{
return (Als)val;
}
}
throw new ArgumentException("The value '" + value + "' is not supported.");
}
要调用它，只需执行以下操作：
Als result = this.GetEnumByStringValueAttribute<Als>(ComboBox.SelectedValue);
Als result = ComboBox.SelectedValue.FromEnumStringValue<Als>();
Als result=this.getEnumByStringValue属性（ComboBox.SelectedValue）；
但这可能不是最好的解决方案，因为它与Als
有关，您可能希望使此代码可重用。您可能希望从我的解决方案中删除代码以返回属性值，然后像您在问题中所做的那样使用Enum.Parse
。我正在使用Microsoft提供的和以下扩展方法：
public static string GetDescription(this Enum value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
string description = value.ToString();
FieldInfo fieldInfo = value.GetType().GetField(description);
DescriptionAttribute[] attributes =
(DescriptionAttribute[])
fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attributes != null && attributes.Length > 0)
{
description = attributes[0].Description;
}
return description;
}
不确定我是否遗漏了什么，你不能这样做吗
Als temp = (Als)combo1.SelectedItem;
int t = (int)temp;
这里有几个扩展方法，我就是为了这个目的而使用的，我已经重写了这些方法来使用您的StringValueAttribute
，但就像我在代码中使用的一样
public static T FromEnumStringValue<T>(this string description) where T : struct {
Debug.Assert(typeof(T).IsEnum);
return (T)typeof(T)
.GetFields()
.First(f => f.GetCustomAttributes(typeof(StringValueAttribute), false)
.Cast<StringValueAttribute>()
.Any(a => a.Value.Equals(description, StringComparison.OrdinalIgnoreCase))
)
.GetValue(null);
}
来自的重复链接，这里有一个与C#7.3的新Enum
type约束一起工作的方法。请注意，您还需要指定它也是一个struct
，以便可以将其设置为可为null的TEnum？
，否则将出现错误
public static TEnum? GetEnumFromDescription<TEnum>(string description)
where TEnum : struct, Enum
{
var comparison = StringComparison.OrdinalIgnoreCase;
foreach (var field in typeof(TEnum).GetFields())
{
var attribute = Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute)) as DescriptionAttribute;
if (attribute != null)
{
if (string.Compare(attribute.Description, description, comparison) == 0)
return (TEnum)field.GetValue(null);
}
if (string.Compare(field.Name, description, comparison) == 0)
return (TEnum)field.GetValue(null);
}
return null;
}
public static TEnum？GetEnumFromDescription（字符串描述）
其中TEnum:struct，Enum
{
var比较=StringComparison.OrdinalIgnoreCase；
foreach（typeof（TEnum）.GetFields（）中的变量字段）
{
var attribute=attribute.GetCustomAttribute（字段，typeof（DescriptionAttribute））作为DescriptionAttribute；
if（属性！=null）
{
if（string.Compare（attribute.Description，Description，comparison）==0）
返回（TEnum）字段。GetValue（null）；
}
if（string.Compare（field.Name、description、comparison）==0）
返回（TEnum）字段。GetValue（null）；
}
返回null；
}
要根据应用于枚举成员的属性值解析字符串值，我建议您使用我的开源库
对于像StringValueAttribute
这样的自定义属性，您可以这样做
为StringValueAttribute.Value
注册并存储自定义EnumFormat
Format = Enums.RegisterCustomEnumFormat(m => m.Attributes.Get<StringValueAttribute>()?.Value);
如果改为使用内置属性（如），则可以这样做
Als result = Enums.Parse<Als>("Niet beantwoord", EnumFormat.Description);
我提出了一个更通用的解决方案。
您可以将它与任何属性一起使用，甚至与字符串以外的其他类型一起使用
using System;
namespace EnumTest
{
public static class EnumExtensions
{
#region Get enum from Attribute
/// <summary>
/// Searches the enum element which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// Throws exception, if there is no enum element found which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// </summary>
/// <param name="attributeType">the type of the attribute. e.g. typeof(System.ComponentModel.DescriptionAttribute)</param>
/// <param name="attributePropertyName">the property of the attribute to search. At DescriptionAttribute, this is "Description"</param>
/// <param name="searchValue">the value to search</param>
public static TEnum FromAttributeValueToEnum<TEnum>(Type attributeType, string attributePropertyName, object searchValue)
where TEnum : struct, Enum
{
TEnum? result = FromAttributeValueToNullableEnum<TEnum>(attributeType, attributePropertyName, searchValue);
if (result.HasValue)
{
return result.Value;
}
Type enumType = typeof(TEnum);
throw new ArgumentException($"The enum type {enumType.FullName} has no element with a {attributeType.FullName} with {attributePropertyName} property equivalent to '{searchValue}'");
}
/// <summary>
/// Searches the enum element which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// Returns fallBackValue, if there is no enum element found which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// </summary>
/// <param name="attributeType">the type of the attribute. e.g. typeof(System.ComponentModel.DescriptionAttribute)</param>
/// <param name="attributePropertyName">the property of the attribute to search. At DescriptionAttribute, this is "Description"</param>
/// <param name="searchValue">the value to search</param>
public static TEnum FromAttributeValueToEnum<TEnum>(Type attributeType, string attributePropertyName, object searchValue, TEnum fallBackValue)
where TEnum : struct, Enum
{
TEnum? result = FromAttributeValueToNullableEnum<TEnum>(attributeType, attributePropertyName, searchValue);
if (result.HasValue)
{
return result.Value;
}
return fallBackValue;
}
/// <summary>
/// Searches the enum element which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// Returns null, if there is no enum element found which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// </summary>
/// <param name="attributeType">the type of the attribute. e.g. typeof(System.ComponentModel.DescriptionAttribute)</param>
/// <param name="attributePropertyName">the property of the attribute to search. At DescriptionAttribute, this is "Description"</param>
/// <param name="searchValue">the value to search</param>
public static TEnum? FromAttributeValueToNullableEnum<TEnum>(Type attributeType, string attributePropertyName, object searchValue)
where TEnum : struct, Enum
{
Type enumType = typeof(TEnum);
if (!enumType.IsEnum)
{
throw new ArgumentException($"The type {enumType.FullName} is no Enum!");
}
if (attributeType == null)
{
throw new ArgumentNullException(nameof(attributeType));
}
if (!typeof(Attribute).IsAssignableFrom(attributeType))
{
throw new ArgumentException($"The type {attributeType.FullName} is no Attribute!", nameof(attributeType));
}
var propertyInfoAttributePropertyName = attributeType.GetProperty(attributePropertyName);
if (propertyInfoAttributePropertyName == null)
{
throw new ArgumentException($"The type {attributeType.FullName} has no (public) property with name {attributePropertyName}", nameof(attributeType));
}
foreach (var field in enumType.GetFields())
{
var attribute = Attribute.GetCustomAttribute(field, attributeType);
if (attribute == null)
{
continue;
}
object attributePropertyValue = propertyInfoAttributePropertyName.GetValue(attribute);
if (attributePropertyValue == null)
{
continue;
}
if (attributePropertyValue.Equals(searchValue))
{
return (TEnum)field.GetValue(null);
}
}
return null;
}
#endregion
}
}
使用系统；
命名空间枚举测试
{
公共静态类枚举扩展
{
#区域从属性获取枚举
///
///搜索具有[attributeType]属性且attributePropertyName等效于searchValue的枚举元素。
///如果未找到具有attributePropertyName等效于searchValue的[attributeType]属性的枚举元素，则引发异常。
///
///属性的类型，例如typeof（System.ComponentModel.DescriptionAttribute）
///要搜索的属性的属性。在DescriptionAttribute中，这是“Description”
///要搜索的值
公共静态TEnum FromAttributeValueToEnum（类型attributeType、字符串attributePropertyName、对象searchValue）
其中TEnum:struct，Enum
{
TEnum？结果=从AttributeValue到UllableEnum（attributeType、attributePropertyName、searchValue）；
if（result.HasValue）
{
返回结果值；
}
类型enumType=typeof（TEnum）；
抛出新的ArgumentException（$“枚举类型{enumType.FullName}没有具有{attributeType.FullName}且{attributePropertyName}属性等于{searchValue}”的元素）；
}
///
///搜索具有[attributeType]属性且attributePropertyName等效于searchValue的枚举元素。
///如果未找到具有attributePropertyName等效于searchValue的[attributeType]属性的枚举元素，则返回fallBackValue。
///
///属性的类型，例如typeof（System.ComponentModel.DescriptionAttribute）
///要搜索的属性的属性。在DescriptionAttribute中，这是“Description”
///要搜索的值
公共静态TEnum FromAttributeValueToEnum（类型attributeType、字符串attributePropertyName、对象searchValue、TEnum fallBackValue）
其中TEnum:struct，Enum
{
TEnum？结果=从AttributeValue到UllableEnum（attributeType、attributePropertyName、searchValue）；
if（result.HasValue）
{
返回结果值；
}
返回回退值；
}
///
///搜索具有[attributeType]属性且attributePropertyName等效于searchValue的枚举元素。
///如果未找到具有attributePropertyName等效于searchValue的[attributeType]属性的枚举元素，则返回null。
///
///属性的类型，例如typeof（System.ComponentModel.DescriptionAttribute）
///要搜索的属性的属性。在DescriptionAttribute中，这是“Description”
///要搜索的值
公共静态TEnum？从AttributeValue到UllableEnum（类型attributeType、字符串attributePropertyName、对象searchValue）
其中TEnum:struct，Enum
{
类型enumType=typeof（TEnum）；
如果（！enumType.IsEnum）
{
抛出新ArgumentException（$“类型{enumType.FullName}不是枚举！”）；
}
if（attributeType==null）
{
抛出新ArgumentNullException（nameof（attributeType））；
}
如果（！typeof（Attribute）.IsAssignableFrom（attributeType））
public static TEnum? GetEnumFromDescription<TEnum>(string description)
where TEnum : struct, Enum
{
var comparison = StringComparison.OrdinalIgnoreCase;
foreach (var field in typeof(TEnum).GetFields())
{
var attribute = Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute)) as DescriptionAttribute;
if (attribute != null)
{
if (string.Compare(attribute.Description, description, comparison) == 0)
return (TEnum)field.GetValue(null);
}
if (string.Compare(field.Name, description, comparison) == 0)
return (TEnum)field.GetValue(null);
}
return null;
}
Format = Enums.RegisterCustomEnumFormat(m => m.Attributes.Get<StringValueAttribute>()?.Value);
Als result = Enums.Parse<Als>("Niet beantwoord", Format); // result == Als.NietBeantwoord
Als result = Enums.Parse<Als>("Niet beantwoord", EnumFormat.Description);
string value = Als.NietBeantwoord.AsString(Format); // value == "Niet beantwoord"
using System;
namespace EnumTest
{
public static class EnumExtensions
{
#region Get enum from Attribute
/// <summary>
/// Searches the enum element which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// Throws exception, if there is no enum element found which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// </summary>
/// <param name="attributeType">the type of the attribute. e.g. typeof(System.ComponentModel.DescriptionAttribute)</param>
/// <param name="attributePropertyName">the property of the attribute to search. At DescriptionAttribute, this is "Description"</param>
/// <param name="searchValue">the value to search</param>
public static TEnum FromAttributeValueToEnum<TEnum>(Type attributeType, string attributePropertyName, object searchValue)
where TEnum : struct, Enum
{
TEnum? result = FromAttributeValueToNullableEnum<TEnum>(attributeType, attributePropertyName, searchValue);
if (result.HasValue)
{
return result.Value;
}
Type enumType = typeof(TEnum);
throw new ArgumentException($"The enum type {enumType.FullName} has no element with a {attributeType.FullName} with {attributePropertyName} property equivalent to '{searchValue}'");
}
/// <summary>
/// Searches the enum element which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// Returns fallBackValue, if there is no enum element found which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// </summary>
/// <param name="attributeType">the type of the attribute. e.g. typeof(System.ComponentModel.DescriptionAttribute)</param>
/// <param name="attributePropertyName">the property of the attribute to search. At DescriptionAttribute, this is "Description"</param>
/// <param name="searchValue">the value to search</param>
public static TEnum FromAttributeValueToEnum<TEnum>(Type attributeType, string attributePropertyName, object searchValue, TEnum fallBackValue)
where TEnum : struct, Enum
{
TEnum? result = FromAttributeValueToNullableEnum<TEnum>(attributeType, attributePropertyName, searchValue);
if (result.HasValue)
{
return result.Value;
}
return fallBackValue;
}
/// <summary>
/// Searches the enum element which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// Returns null, if there is no enum element found which has a [attributeType] attribute with a attributePropertyName equivalent to searchValue.
/// </summary>
/// <param name="attributeType">the type of the attribute. e.g. typeof(System.ComponentModel.DescriptionAttribute)</param>
/// <param name="attributePropertyName">the property of the attribute to search. At DescriptionAttribute, this is "Description"</param>
/// <param name="searchValue">the value to search</param>
public static TEnum? FromAttributeValueToNullableEnum<TEnum>(Type attributeType, string attributePropertyName, object searchValue)
where TEnum : struct, Enum
{
Type enumType = typeof(TEnum);
if (!enumType.IsEnum)
{
throw new ArgumentException($"The type {enumType.FullName} is no Enum!");
}
if (attributeType == null)
{
throw new ArgumentNullException(nameof(attributeType));
}
if (!typeof(Attribute).IsAssignableFrom(attributeType))
{
throw new ArgumentException($"The type {attributeType.FullName} is no Attribute!", nameof(attributeType));
}
var propertyInfoAttributePropertyName = attributeType.GetProperty(attributePropertyName);
if (propertyInfoAttributePropertyName == null)
{
throw new ArgumentException($"The type {attributeType.FullName} has no (public) property with name {attributePropertyName}", nameof(attributeType));
}
foreach (var field in enumType.GetFields())
{
var attribute = Attribute.GetCustomAttribute(field, attributeType);
if (attribute == null)
{
continue;
}
object attributePropertyValue = propertyInfoAttributePropertyName.GetValue(attribute);
if (attributePropertyValue == null)
{
continue;
}
if (attributePropertyValue.Equals(searchValue))
{
return (TEnum)field.GetValue(null);
}
}
return null;
}
#endregion
}
}
Als Beantwoord = EnumExtensions.FromAttributeValueToEnum<Als>(typeof(StringValueAttribute), nameof(StringValueAttribute.Value), "Beantwoord");
public class IntValueAttribute : Attribute
{
public IntValueAttribute(int value)
{
Value = value;
}
public int Value { get; private set; }
}
public enum EnumSample
{
[Description("Eins")]
[IntValue(1)]
One,
[Description("Zwei")]
[IntValue(2)]
Two,
[Description("Drei")]
[IntValue(3)]
Three
}
EnumSample one = EnumExtensions.FromAttributeValueToEnum<EnumSample>(typeof(DescriptionAttribute), nameof(DescriptionAttribute.Description), "Eins");
EnumSample two = EnumExtensions.FromAttributeValueToEnum<EnumSample>(typeof(IntValueAttribute), nameof(IntValueAttribute.Value), 2);