我知道下面是不可能的,因为枚举的类型必须是int

enum GroupTypes
{
    TheGroup = "OEM",
    TheOtherGroup = "CMB"
}

从我的数据库中,我得到了一个不全面的代码字段(OEM和CMBs)。我想让这个字段成为一个枚举或其他可以理解的东西。因为如果目标是可读性,解决方案就应该简洁。

我还有其他选择吗?


当前回答

根据其他人的意见,这是我想到的。这种方法避免了在想要获得常量值的地方键入. value。

我有一个基类的所有字符串枚举像这样:

using System;
using Newtonsoft.Json;

[JsonConverter(typeof(ConstantConverter))]
public class StringEnum: IConvertible
{
    public string Value { get; set; }

    protected StringEnum(string value)
    {
        Value = value;
    }

    public static implicit operator string(StringEnum c)
    {
        return c.Value;
    }
    public string ToString(IFormatProvider provider)
    {
        return Value;
    }

    public TypeCode GetTypeCode()
    {
        throw new NotImplementedException();
    }

    public bool ToBoolean(IFormatProvider provider)
    {
        throw new NotImplementedException();
    }
    //The same for all the rest of IConvertible methods
}

JsonConverter是这样的:

using System;
using Newtonsoft.Json;

class ConstantConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return true;
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        if (value == null)
        {
            serializer.Serialize(writer, null);
        }
        else
        {
            serializer.Serialize(writer, value.ToString());
        }
    }
}

一个实际的string enum是这样的:

public sealed class Colors : StringEnum
{
    public static Colors Red { get { return new Catalog("Red"); } }
    public static Colors Yellow { get { return new Catalog("Yellow"); } }
    public static Colors White { get { return new Catalog("White"); } }

    private Colors(string value) : base(value) { }
}

有了这个,你可以使用颜色。红色甚至序列化到json而不使用Value属性

其他回答

我喜欢在类中使用属性而不是方法,因为它们看起来更像枚举。

下面是一个Logger的例子:

public class LogCategory
{
    private LogCategory(string value) { Value = value; }

    public string Value { get; private set; }

    public static LogCategory Trace   { get { return new LogCategory("Trace"); } }
    public static LogCategory Debug   { get { return new LogCategory("Debug"); } }
    public static LogCategory Info    { get { return new LogCategory("Info"); } }
    public static LogCategory Warning { get { return new LogCategory("Warning"); } }
    public static LogCategory Error   { get { return new LogCategory("Error"); } }

    public override string ToString()
    {
        return Value;
    }
}

传入类型安全的字符串值作为参数:

public static void Write(string message, LogCategory logCategory)
{
    var log = new LogEntry { Message = message };
    Logger.Write(log, logCategory.Value);
}

用法:

Logger.Write("This is almost like an enum.", LogCategory.Info);

我基本上是在寻找@ArthurC的反思答案

稍微扩展一下他的回答,你可以通过一个泛型函数来让它更好:

    // If you want for a specific Enum
    private static string EnumStringValue(GroupTypes e)
    {
        return EnumStringValue<GroupTypes>(e);
    }

    // Generic
    private static string EnumStringValue<T>(T enumInstance)
    {
        return Enum.GetName(typeof(T), enumInstance);
    } 

然后你就可以把你有的东西都包起来了

EnumStringValue(GroupTypes.TheGroup) // if you incorporate the top part

or

EnumStringValue<GroupTypes>(GroupTypes.TheGroup) // if you just use the generic

根据其他人的意见,这是我想到的。这种方法避免了在想要获得常量值的地方键入. value。

我有一个基类的所有字符串枚举像这样:

using System;
using Newtonsoft.Json;

[JsonConverter(typeof(ConstantConverter))]
public class StringEnum: IConvertible
{
    public string Value { get; set; }

    protected StringEnum(string value)
    {
        Value = value;
    }

    public static implicit operator string(StringEnum c)
    {
        return c.Value;
    }
    public string ToString(IFormatProvider provider)
    {
        return Value;
    }

    public TypeCode GetTypeCode()
    {
        throw new NotImplementedException();
    }

    public bool ToBoolean(IFormatProvider provider)
    {
        throw new NotImplementedException();
    }
    //The same for all the rest of IConvertible methods
}

JsonConverter是这样的:

using System;
using Newtonsoft.Json;

class ConstantConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return true;
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        if (value == null)
        {
            serializer.Serialize(writer, null);
        }
        else
        {
            serializer.Serialize(writer, value.ToString());
        }
    }
}

一个实际的string enum是这样的:

public sealed class Colors : StringEnum
{
    public static Colors Red { get { return new Catalog("Red"); } }
    public static Colors Yellow { get { return new Catalog("Yellow"); } }
    public static Colors White { get { return new Catalog("White"); } }

    private Colors(string value) : base(value) { }
}

有了这个,你可以使用颜色。红色甚至序列化到json而不使用Value属性

使用带有常量的静态类如何?

static class GroupTypes
{
  public const string TheGroup = "OEM";
  public const string TheOtherGroup = "CMB";
}

void DoSomething(string groupType)
{
  if(groupType == GroupTypes.TheGroup)
  {
    // Be nice
  }  
  else if (groupType == GroupTypes.TheOtherGroup)
  {
    // Continue to be nice
  }
  else
  {
    // unexpected, throw exception?
  }
}

你也可以使用扩展模型:

public enum MyEnum
{
    [Description("String 1")]
    V1= 1,
    [Description("String 2")]
    V2= 2
} 

你的扩展类

public static class MyEnumExtensions
{
    public static string ToDescriptionString(this MyEnum val)
    {
        DescriptionAttribute[] attributes = (DescriptionAttribute[])val
           .GetType()
           .GetField(val.ToString())
           .GetCustomAttributes(typeof(DescriptionAttribute), false);
        return attributes.Length > 0 ? attributes[0].Description : string.Empty;
    }
} 

用法:

MyEnum myLocal = MyEnum.V1;
print(myLocal.ToDescriptionString());