Automapper枚举到枚举类 [英] Automapper enum to Enumeration Class

问题描述

我试图用Automapper从一个普通枚举枚举类（如吉米·博加德描述地图 - 的 http://lostechies.com/jimmybogard/2008/08/12/enumeration-classes/ ）。作为枚举类不经常枚举不具有相同的价值观。因此，我想尽可能使用该名称映射：

I'm trying to use Automapper to map from a regular enum to an Enumeration Class (as described by Jimmy Bogard - http://lostechies.com/jimmybogard/2008/08/12/enumeration-classes/). The regular enum doesn't have the same values as the enumeration class does. I would therefore like to map using the Name if possible:

枚举：

public enum ProductType
{
    ProductType1,
    ProductType2
}

枚举类：

public class ProductType : Enumeration
{
    public static ProductType ProductType1 = new ProductType(8, "Product Type 1");
    public static ProductType ProductType2 = new ProductType(72, "Product Type 2");

    public ProductType(int value, string displayName)
        : base(value, displayName)
    {
    }

    public ProductType()
    {
    }
}

任何帮助，使这个映射工作表示赞赏！我曾尝试只是一个普通的映射：

Any help to make this mapping work appreciated! I have attempted just a regular mapping:

Mapper.Map<ProductType, Domain.ProductType>();

..但映射类型都有值为0。

.. but the mapped type has a value of 0.

谢谢，
亚历

推荐答案

下面是Automapper如何工作 - 它得到公众的例如的性能/目标类型的字段，以及与公众的实例相匹配的的性能/源类型的字段。您枚举不具有公共属性。枚举类有两个 - 值和显示名称。没有什么可以映射为Automapper。您可以使用最好的事情是简单的映射功能（我喜欢用这个扩展方法）：

Here is how Automapper works - it gets public instance properties/fields of destination type, and matches the with public instance properties/fields of source type. Your enum does not have public properties. Enumeration class has two - Value and DisplayName. There is nothing to map for Automapper. Best thing you can use is simple mapper function (I like to use extension methods for that):

public static Domain.ProductType ToDomainProductType(
    this ProductType productType)
{
    switch (productType)
    {
        case ProductType.ProductType1:
            return Domain.ProductType.ProductType1;
        case ProductType.ProductType2:
            return Domain.ProductType.ProductType2;
        default:
            throw new ArgumentException();
    }
}

用法：

Usage:

ProductType productType = ProductType.ProductType1;
var result = productType.ToDomainProductType();

如果你真的想在这种情况下使用Automapper，你ca的提供这种创作方法 ConstructUsing 映射的表达方式：

If you really want to use Automapper in this case, you ca provide this creation method to ConstructUsing method of mapping expression:

Mapper.CreateMap<ProductType, Domain.ProductType>()
      .ConstructUsing(Extensions.ToDomainProductType);

您还可以将这种创作方法 Domain.ProductType 类。然后创建从给定的枚举值它的实例会看起来像：

You also can move this creation method to Domain.ProductType class. Then creating its instance from given enum value will look like:

var result = Domain.ProductType.Create(productType);

---

更新：您可以使用反射来创建通用的方法它映射枚举和相应的枚举类的：

---

UPDATE: You can use reflection to create generic method which maps between enums and appropriate enumeration class:

public static TEnumeration ToEnumeration<TEnum, TEnumeration>(this TEnum value)
{
    string name = Enum.GetName(typeof(TEnum), value);
    var field = typeof(TEnumeration).GetField(name);
    return (TEnumeration)field.GetValue(null);
}

用法：

Usage:

var result = productType.ToEnumeration<ProductType, Domain.ProductType>();

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