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?
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
使用类。
编辑:更好的例子
class StarshipType
{
private string _Name;
private static List<StarshipType> _StarshipTypes = new List<StarshipType>();
public static readonly StarshipType Ultralight = new StarshipType("Ultralight");
public static readonly StarshipType Light = new StarshipType("Light");
public static readonly StarshipType Mediumweight = new StarshipType("Mediumweight");
public static readonly StarshipType Heavy = new StarshipType("Heavy");
public static readonly StarshipType Superheavy = new StarshipType("Superheavy");
public string Name
{
get { return _Name; }
private set { _Name = value; }
}
public static IList<StarshipType> StarshipTypes
{
get { return _StarshipTypes; }
}
private StarshipType(string name, int systemRatio)
{
Name = name;
_StarshipTypes.Add(this);
}
public static StarshipType Parse(string toParse)
{
foreach (StarshipType s in StarshipTypes)
{
if (toParse == s.Name)
return s;
}
throw new FormatException("Could not parse string.");
}
}
其他回答
这里是扩展方法,我用来获得枚举值作为字符串。首先是枚举。
public enum DatabaseEnvironment
{
[Description("AzamSharpBlogDevDatabase")]
Development = 1,
[Description("AzamSharpBlogQADatabase")]
QualityAssurance = 2,
[Description("AzamSharpBlogTestDatabase")]
Test = 3
}
Description属性来自System.ComponentModel。
这是我的扩展方法:
public static string GetValueAsString(this DatabaseEnvironment environment)
{
// get the field
var field = environment.GetType().GetField(environment.ToString());
var customAttributes = field.GetCustomAttributes(typeof (DescriptionAttribute), false);
if(customAttributes.Length > 0)
{
return (customAttributes[0] as DescriptionAttribute).Description;
}
else
{
return environment.ToString();
}
}
现在,你可以使用下面的代码访问枚举字符串值:
[TestFixture]
public class when_getting_value_of_enum
{
[Test]
public void should_get_the_value_as_string()
{
Assert.AreEqual("AzamSharpBlogTestDatabase",DatabaseEnvironment.Test.GetValueAsString());
}
}
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
你可以很容易地做到。使用下面的代码。
enum GroupTypes
{
OEM,
CMB
};
然后,当您想获取每个枚举元素的字符串值时,只需使用下面的代码行。
String oemString = Enum.GetName(typeof(GroupTypes), GroupTypes.OEM);
我曾经成功地使用过这个方法,我也使用过一个常量类来保存字符串常量,两者都很好,但我倾向于这样做。
可以向枚举中的项添加属性,然后使用反射从属性中获取值。
你必须使用"field"说明符来应用属性,如下所示:
enum GroupTypes
{
[field:Description("OEM")]
TheGroup,
[field:Description("CMB")]
TheOtherGroup
}
然后你将反射枚举类型的静态字段(在本例中是GroupTypes),并使用反射获取你正在寻找的值的DescriptionAttribute:
public static DescriptionAttribute GetEnumDescriptionAttribute<T>(
this T value) where T : struct
{
// The type of the enum, it will be reused.
Type type = typeof(T);
// If T is not an enum, get out.
if (!type.IsEnum)
throw new InvalidOperationException(
"The type parameter T must be an enum type.");
// If the value isn't defined throw an exception.
if (!Enum.IsDefined(type, value))
throw new InvalidEnumArgumentException(
"value", Convert.ToInt32(value), type);
// Get the static field for the value.
FieldInfo fi = type.GetField(value.ToString(),
BindingFlags.Static | BindingFlags.Public);
// Get the description attribute, if there is one.
return fi.GetCustomAttributes(typeof(DescriptionAttribute), true).
Cast<DescriptionAttribute>().SingleOrDefault();
}
我选择在上面返回DescriptionAttribute本身,以便您能够确定是否应用了该属性。
在VS 2015中,你可以使用nameof
public class LogCategory
{
public static string Trace;
public static string Debug;
public static string Info;
public static string Warning;
public static string Error;
}
用法:
Logger.Write("This is almost like an enum.", nameof(LogCategory.Info));