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具有默认类型转换的枚举？那可能吗？

发布于 2024-07-19 08:49:53 字数 83 浏览 1 评论 0原文

是否可以为枚举进行默认类型转换？

我经常使用枚举，例如状态，并且我想将枚举直接与 LINQ 字段进行比较，但我必须始终进行类型转换。

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叫嚣ゝ 2024-07-26 08:49:54

您应该能够在 LINQ 对象中拥有具有枚举类型的属性。这样你就不必施放。

因此，只需更改您的属性以具有正确的枚举类型，您就不必再担心强制转换。您可以在 LINQtoSQL 设计器中执行此操作。只需右键单击某个属性，选择“属性”，然后在 Visual Studio 属性窗口中设置适当的类型。

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夏雨凉 2024-07-26 08:49:54

答案要简单得多！

我的一个好朋友告诉我这很简单！看看这个样本！

public enum State:byte
{
    EmailNotValidated = 0x00,
    EmailValidated = 0x10,
    Admin_AcceptPending = 0x40,
    Active = 0x80,
    Admin_BlockedAccount = 0xff
}

请注意枚举名称后面的 :BYTE 部分...这就是我一直在寻找的技巧！但感谢每个为我努力的人！

The answer was MUCH more simple!!!

A good friend of mine told me this is very simple! have a look at this sample!

public enum State:byte
{
    EmailNotValidated = 0x00,
    EmailValidated = 0x10,
    Admin_AcceptPending = 0x40,
    Active = 0x80,
    Admin_BlockedAccount = 0xff
}

Pay attention to the :BYTE part after the name of the Enum... there is the trick I was looking for! But thanks to everyone trying for me!

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何处潇湘 2024-07-26 08:49:54

LINQ-to-SQL 通常会处理直接整数映射和精确字符串（名称）映射（注意：区分大小写）。含义：将枚举写入某处，然后在设计器中将属性类型设置为完全限定的枚举名称：Some.Namespace.MyEnum。它通常应该有效。

对于重要的映射（例如，列是具有混合大小写值的 varchar，或者诸如“进行中”[注意空格]），您必须将存储属性保留为 int/varchar （等）并手动映射它。我通常通过将其标记为私有并将其命名为 FooStorage，并在分部类中添加映射属性来实现此目的：

partial class MyType {
    public MyEnum Foo {
        get {... mapping logic reading from FooStorage...}
        set {... mapping logic, updating FooStorage...}
    }
}

唯一的问题是 LINQ 查询仅适用于存储财产（不是定制财产）。

LINQ-to-SQL will usually handle direct integer maps and exact string (name) maps (note: case sensitive). Meaning: write your enum somewhere, and in the designer set the property type as the fully-qualified enum name: Some.Namespace.MyEnum. It should usually work.

For non-trivial mappings (for example where the column is a varchar with mixed-case values, or things like "In Progress" [note the space]), you will have to leave the storage property as int/varchar (etc) and map it manually. I usually do this by marking it as private and naming it FooStorage, and adding a mapping property in a partial class:

partial class MyType {
    public MyEnum Foo {
        get {... mapping logic reading from FooStorage...}
        set {... mapping logic, updating FooStorage...}
    }
}

The only problem is that LINQ queries will only work against the storage property (not the bespoke property).

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最美不过初阳 2024-07-26 08:49:54

您尝试过扩展方法吗？

public enum MyEnum
{
    First = 1,
    Second = 2,
    Third = 3
}

public static class Utility
{
    public static string Description(this Enum e)
    {
        Type t = e.GetType();
        DescriptionAttribute[] desc =
            (DescriptionAttribute[])(t.GetField(e.ToString())
            .GetCustomAttributes(typeof(DescriptionAttribute), false));
        return desc.Length > 0 ? desc[0].Description : e.ToString();
    }
    public static byte ToByte(this Enum ai)
    {
        object o=Enum.ToObject(ai.GetType(), ai);
        return Convert.ToByte(o);
    }
}


class Program
{
    static void Main(string[] args)
    {
        MyEnum me = MyEnum.Third;

        Console.WriteLine("Value: {0}\r\nType: {1}"
        ,me.ToByte(),me.ToByte().GetType().ToString());

        Console.ReadLine();
    }
}

它输出：

值：3

类型：System.Byte

Have you tried extension methods?

public enum MyEnum
{
    First = 1,
    Second = 2,
    Third = 3
}

public static class Utility
{
    public static string Description(this Enum e)
    {
        Type t = e.GetType();
        DescriptionAttribute[] desc =
            (DescriptionAttribute[])(t.GetField(e.ToString())
            .GetCustomAttributes(typeof(DescriptionAttribute), false));
        return desc.Length > 0 ? desc[0].Description : e.ToString();
    }
    public static byte ToByte(this Enum ai)
    {
        object o=Enum.ToObject(ai.GetType(), ai);
        return Convert.ToByte(o);
    }
}


class Program
{
    static void Main(string[] args)
    {
        MyEnum me = MyEnum.Third;

        Console.WriteLine("Value: {0}\r\nType: {1}"
        ,me.ToByte(),me.ToByte().GetType().ToString());

        Console.ReadLine();
    }
}

It outputs:

Value: 3

Type: System.Byte

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