什么是单个键/值对属性附加到一个枚举的最佳方法？ [英] What is the best method for attaching a single key/value pair attribute to an enumeration?

问题描述

我试图找出最好的方法是什么一个键/值对属性附加到一个枚举，其中最关键的是我的 MERCHANTID 和值对应的 TransactionKey 。

I'm trying to figure out what the best method is for attaching a single key/value pair attribute to an enumeration where the key is my MerchantId and the value is the corresponding TransactionKey.

我目前做的是把一个逗号分隔字符串转换为 StringValueAttribute 类：

What I currently do is put a comma delimited string into a StringValueAttribute class:

Public Enum Merchants
    <StringValue("coke,faj80785hq+faf=-1=-jfa+">
        Coke = 0
    <StringValue("pepsi,adfji=-901jnas++fdj98ua")>
        Pepsi = 1
    <StringValue("drpepper,jk878-=+9kdkdja0=a=f--daj")>
        DrPepper = 2
End Enum

Public Property Merchant As Merchants

我拔出钥匙或 MERCHANTID 致电 .GetStringValue（）斯普利特（，C）（0）：

Public ReadOnly Property MerchantId() As String
    Get
        Return Merchant.GetStringValue().Split(","c)(0)
    End Get
End Property

我通过调用 .GetStringValue（）拉出值或 TransactionKey 斯普利特（，C）（1）：

I pull out the value or TransactionKey by calling .GetStringValue().Split(","c)(1):

Public ReadOnly Property TransactionKey() As String
    Get
        Return Merchant.GetStringValue().Split(","c)(1)
    End Get
End Property

---

这是最有效的方式做到这一点？取而代之的 StringValueAttribute ，怎么样使用词典（字符串，字符串）创建一个属性，因为它是一个关键的/值对列表？或字符串数​​组或列表？也许东西在LINQ？或者是干脆已经有效的，因为它可以？

---

Is this the most efficient way to do this? Instead of StringValueAttribute, what about creating an attribute using a Dictionary(Of String, String) since it is a key/value pair list? Or String Array or List? Maybe something in LINQ? Or is it simply already efficient as it can be?

推荐答案

您可以使用下面的自定义属性和扩展方法得到的值。需要注意以下几点：

You can use the following custom attribute and extension methods to get the values. Some things to note:

• 这是在C＃中，希望这是确定：）

• It's in C#, hope that's ok :)

的扩展方法类缓存静态范围MerchantIds和TransactionIds，所以应该是pretty效率。

The extension methods class caches the MerchantIds and TransactionIds in static scope, so should be pretty efficient.

您获得 MERCHANTID 通过调用（例如的） Merchants.Coke.GetMerchantId（）; 。

You get the MerchantId by calling (e.g.) Merchants.Coke.GetMerchantId();.

您获得 TRANSACTIONID 通过调用（例如的） Merchants.Coke.GetTransactionId（）; 。

You get the TransactionId by calling (e.g.) Merchants.Coke.GetTransactionId();.

此外，扩展方法也懒得检查传递给它们的招商局值是有效的，所以你可以通过调用打破它（ （招商）76282）.GetMerchantId（）。

Also, the extension methods don't bother checking that the Merchants value passed to them is valid, so you could break it by calling ((Merchants)76282).GetMerchantId().

[AttributeUsage(AttributeTargets.Field)]
public class MerchantDataAttribute : Attribute
{
    public MerchantDataAttribute(string merchantId, string transactionId)
    {
        this.MerchantId = merchantId;
        this.TransactionId = transactionId;
    }

    public string MerchantId
    {
        get;
        private set;
    }

    public string TransactionId
    {
        get;
        private set;
    }
}

public static class MerchantsExtensions
{
    private static readonly Dictionary<Merchants, MerchantDataAttribute> 
        _merchantsCache = CacheMerchantsCache();

    public static string GetMerchantId(this Merchants merchants)
    {
        return _merchantsCache[merchants].MerchantId;
    }

    public static string GetTransactionId(this Merchants merchants)
    {
        return _merchantsCache[merchants].TransactionId;
    }

    private static Dictionary<Merchants, MerchantDataAttribute> CacheMerchantsCache()
    {
        return Enum.GetValues(typeof(Merchants))
            .Cast<Merchants>()
            .Select(m => new
            {
                Merchant = m, 
                MerchantAttribute = GetMerchantAttribute(m)
            })
            .ToDictionary(m => m.Merchant, m => m.MerchantAttribute);
    }

    private static MerchantDataAttribute GetMerchantAttribute(Merchants merchant)
    {
        return typeof(Merchants)
            .GetMember(merchant.ToString())
            .First()
            .GetCustomAttributes(typeof(MerchantDataAttribute), inherit: false)
            .Cast<MerchantDataAttribute>()
            .First();
    }
}

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