如何教导Automapper将X映射到IContainer< Y&gt ;? [英] How do I teach Automapper to map X to IContainer<Y>?

问题描述

这是从模型到mvvmcross视图模型的映射，在这里您可以使用一些容器类，例如:

This came up mapping from models to mvvmcross viewmodels, where you have some container classes you might use, for example:

namespace MvvmCross.Binding
{
  interface INC<T>
  {
    T Value { get; set; }
  }
}
class model
{
  String name { get; set; }
  DateTime when { get; set; }
  othermodel data { get; set; }
}
class viewmodel
{
  INC<String> Name { get; set; }
  INC<String> When { get; set; }
  INC<otherviewmodel> Data { get; set; }
}

• 我需要教AutoMapper在不指定A或B的情况下从A映射到INC<B>(并反向).

  • I need to teach AutoMapper to map from A to INC<B> (and back), without specifiying A or B.

    应该创建空目标INC<>，不应该重新创建非null.

    Null destination INC<> should be created, non-null should not be re-created.

    映射应继续以使destination.Value = Mapper.Map<A,B>(source).

    映射null --> INC<T>应该导致INC<T>.Value = SomeDefaultValue

    推荐答案

    使用ForAllMaps，您可以获取源/目标类型并提供封闭的，完全通用的转换器类型.如果您想直接调用-Map<X,IContainer<Y>，但这没有帮助，但是您不需要.

    By using ForAllMaps, you can get the source/destination types and provide a closed, fully generic converter type. This doesn't help if you want to directly call -Map<X,IContainer<Y>, but you shouldn't need to.

    Mapper.Initialize(c =>
    {
        c.CreateMap<model, viewmodel>().ReverseMap();
        c.ForAllMaps((p, mc) =>
        {
            Type st = p.SourceType, sct = GetContained(st);
            Type dt = p.DestinationType, dct = GetContained(dt);
            if (sct != null) mc.ConvertUsing(typeof(TCReverse<,>).MakeGenericType(sct, dt));
            if (dct != null) mc.ConvertUsing(typeof(TCForward<,>).MakeGenericType(st, dct));
        });
    });
    Mapper.AssertConfigurationIsValid();
    Mapper.Map<viewmodel>(new model());
    Mapper.Map<model>(new viewmodel());
    

    使用简单的转换器:

    public class TCReverse<X,Y> : ITypeConverter<IContainer<X>, Y>
    {
        public Y Convert(IContainer<X> source, Y destination, ResolutionContext context)
        {
            var use = source == null ? default(X) : source.Value;
            return context.Mapper.Map(use, destination);
        }
    }
    
    public class TCForward<X,Y> : ITypeConverter<X, IContainer<Y>>
    {
        public IContainer<Y> Convert(X source, IContainer<Y> destination, ResolutionContext context)
        {
            if (destination == null)
                destination = new Container<Y>();
            destination.Value = context.Mapper.Map(source, destination.Value);
            return destination;
        }
    }
    

    我在这里使用了辅助方法:

    And I used a helper method here:

    Type GetContained(Type t)
    {
        return t.GetInterfaces()
                .Concat(new[] { t })
                .Where(x => x.IsGenericType)
                .Where(x => typeof(IContainer<>).IsAssignableFrom(x.GetGenericTypeDefinition()))
                .Select(x => x.GenericTypeArguments[0])
                .FirstOrDefault();
    }
    

    这篇关于如何教导Automapper将X映射到IContainer< Y&gt ;?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！