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

我只需创建一个字典,并使用代码作为键。

编辑:为了解决关于执行反向查找(查找键)的注释,这将不是非常有效。如果有必要,我将编写一个新类来处理它。

其他回答

public class DataType
{
    private readonly string value;
    private static readonly Dictionary<string, DataType> predefinedValues;

    public static readonly DataType Json = new DataType("json");
    public static readonly DataType Xml = new DataType("xml");
    public static readonly DataType Text = new DataType("text");
    public static readonly DataType Html = new DataType("html");
    public static readonly DataType Binary = new DataType("binary");

    static DataType()
    {
        predefinedValues = new Dictionary<string, DataType>();
        predefinedValues.Add(Json.Value, Json);
        predefinedValues.Add(Xml.Value, Xml);
        predefinedValues.Add(Text.Value, Text);
        predefinedValues.Add(Html.Value, Html);
        predefinedValues.Add(Binary.Value, Binary);
    }

    private DataType(string value)
    {
        this.value = value;
    }

    public static DataType Parse(string value)
    {
        var exception = new FormatException($"Invalid value for type {nameof(DataType)}");
        if (string.IsNullOrEmpty(value))
            throw exception;

        string key = value.ToLower();
        if (!predefinedValues.ContainsKey(key))
            throw exception;

        return predefinedValues[key];
    }

    public string Value
    {
        get { return value; }
    }
}

基于https://stackoverflow.com/a/1343517/1818723,我提出了一个枚举与TryParse方法

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

    public string Value { get; private set; }

    private static List<FancyStringEnum> choices = new List<FancyStringEnum>
    {
        new FancyStringEnum("Small") ,
        new FancyStringEnum("Big Thing") ,
        new FancyStringEnum("Value with Spaces")
    };

    public static FancyStringEnum Small { get { return choices[0]; } }
    public static FancyStringEnum BigThing { get { return choices[1]; } }
    public static FancyStringEnum ValueWithSpaces { get { return choices[2]; } }

    public override string ToString()
    {
        return Value;
    }

    public static bool TryParse(string value, bool ignoreCase, out FancyStringEnum result)
    {
        var sc = StringComparison.InvariantCulture;
        if (ignoreCase)
            sc = StringComparison.InvariantCultureIgnoreCase;

        foreach (var choice in choices)
        {

            if (choice.Value.Equals(value, sc))
            {
                result = choice;
                return true;
            }
        }

        result = new FancyStringEnum(null);
        return false;
    }

    public static FancyStringEnum Parse(string value, bool ignoreCase)
    {
        var sc = StringComparison.InvariantCulture;
        if (ignoreCase)
            sc = StringComparison.InvariantCultureIgnoreCase;

        foreach (var choice in choices)
        {

            if (choice.Value.Equals(value, sc))
            {
                return choice;
            }
        }

        return new FancyStringEnum(null);
    }
}

传入类型安全的字符串值作为参数:

public static void Do(string message, FancyStringEnum value)
{
    if (value == FancyStringEnum.Small)
    {
        //do something
    } else if (value == FancyStringEnum.BigThing)
    {
        //do something else
    }
}

TryParse和Parse在行动:

string something = "something"; //substiture with "small" to see it parsed 
if (FancyStringEnum.TryParse(something, true, out var se))
    Console.WriteLine(se.Value);
else
    Console.WriteLine($"unable to parse {something}");

//or    

var v2 = FancyStringEnum.Parse(something, true);
if (v2.Value == null)
    Console.WriteLine($"unable to parse {something}");
else
    Console.WriteLine(v2.Value); //do something with parsed enum

    

是否可以提取基类,用更少的代码创建StringEnums

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());

Glennular Extension方法的一个小调整,所以你可以在其他东西上使用扩展,而不仅仅是ENUM的;

using System;
using System.ComponentModel;
namespace Extensions {
    public static class T_Extensions {
        /// <summary>
        /// Gets the Description Attribute Value
        /// </summary>
        /// <typeparam name="T">Entity Type</typeparam>
        /// <param name="val">Variable</param>
        /// <returns>The value of the Description Attribute or an Empty String</returns>
        public static string Description<T>(this T t) {
            DescriptionAttribute[] attributes = (DescriptionAttribute[])t.GetType().GetField(t.ToString()).GetCustomAttributes(typeof(DescriptionAttribute), false);
            return attributes.Length > 0 ? attributes[0].Description : string.Empty;
        }
    }
}

或者使用Linq

using System;
using System.ComponentModel;
using System.Linq;

namespace Extensions {


public static class T_Extensions {
        public static string Description<T>(this T t) =>
            ((DescriptionAttribute[])t
            ?.GetType()
            ?.GetField(t?.ToString())
            ?.GetCustomAttributes(typeof(DescriptionAttribute), false))
            ?.Select(a => a?.Description)
            ?.FirstOrDefault() 
            ?? string.Empty;  
    }
}

我会把它变成一个类,完全避免使用枚举。然后使用类型处理程序,你可以在从db中获取对象时创建对象。

即:

public class Group
{
    public string Value{ get; set; }
    public Group( string value ){ Value = value; } 
    public static Group TheGroup() { return new Group("OEM"); }
    public static Group OtherGroup() { return new Group("CMB"); }

}