Question

源类：

public class Post
{
    public long ID { get; set; }

    [Column(TypeName="nvarchar")]
    [Required]
    [StringLength(250)]
    public string Name { get; set; }

    [Column(TypeName="varchar")]
    [StringLength(250)]
    public string UrlName { get; set; }

    [Column(TypeName="ntext")]
    public string Excerpt { get; set; }

    [Column(TypeName="ntext")]
    [Required]
    public string Content { get; set; }

    public DateTime PostedTime { get; set; }
    public DateTime? PublishedTime { get; set; }
    public DateTime? LastUpdatedTime { get; set; }
    public bool IsPublished { get; set; }

    public virtual List<Category> Categories { get; set; }
    public virtual List<Comment> Comments { get; set; }
    public virtual List<Tag> Tags { get; set; }
}

目的地类

public class Post : Model
{
    public long ID { get; set; }
    public string Name { get; set; }
    public string UrlName { get; set; }
    public string Excerpt { get; set; }
    public string Content { get; set; }
    public DateTime PostedTime { get; set; }
    public DateTime LastCommentedTime { get; set; }
    public bool IsPublished { get; set; }

    public List<Category> Category { get; set; }
    public List<Comment> Comments { get; set; }
    public List<Tag> Tags { get; set; }
}

我尝试使用EmitMapper相互映射;当从源到desction的映射时，这里是代码示例：

[TestMethod]
    public void ShouleMapEntityToModel()
    {
        Post eP = new Post();
        eP.ID = 2;
        eP.Comments = new List<Comment>();

        eP.Comments.Add(new Comment()
            {
                ID = 2,
                Author = "derek"
            });

        var mP = eP.Map<Post, mBlog.Core.Models.Post>();

        Assert.IsNotNull(mP);
        Assert.AreEqual(1, mP.Comments.Count());
    }

我得到了一个例外，

测试方法mBlog.Test.EmitMapperTest.ShouleMapEntityToModel抛出异常： System.Exception：在System.Collections.Generic.IList`1 [[mBlog.Core.Models.Post，mBlog.Core，Version = 1.0.0.0，Culture = neutral，PublicKeyToken = null]中找不到类型[]的构造方法

Answer 1

我遇到了同样的问题，但我找到了解决方案。不要为目标对象使用列表。如果在mBlog.Core.Models.Post对象中使用简单数组，则应该得到一个很好的填充对象。所以你的目的地类应该是这样的：

public class Post : Model
{
    public long ID { get; set; }
    public string Name { get; set; }
    public string UrlName { get; set; }
    public string Excerpt { get; set; }
    public string Content { get; set; }
    public DateTime PostedTime { get; set; }
    public DateTime LastCommentedTime { get; set; }
    public bool IsPublished { get; set; }

    public Category[] Category { get; set; }
    public Comment[] Comments { get; set; }
    public Tag[] Tags { get; set; }
}

Answer 2

这个答案显示了如何处理IEnumerable到IEnumerable：EmitMapper and List

我相信这也适用于这种情况。看看：

这可以创建自定义类，实现接口“ICustomConverterProvider”并将ConvertGeneric添加到“DefaultMapConfig”。

查看EmitMapper的源代码，我发现了一个名为“ArraysConverterProvider”的类，它是从ICollections到Arrays的默认通用转换器。

调整此类中的代码以使用IEnumerable 集合：

class GenericIEnumerableConverterProvider : ICustomConverterProvider
    {
      public CustomConverterDescriptor GetCustomConverterDescr(
            Type from,
            Type to,
            MapConfigBaseImpl mappingConfig)
        {
            var tFromTypeArgs = DefaultCustomConverterProvider.GetGenericArguments(from);
            var tToTypeArgs = DefaultCustomConverterProvider.GetGenericArguments(to);
            if (tFromTypeArgs == null || tToTypeArgs == null || tFromTypeArgs.Length != 1 || tToTypeArgs.Length != 1)
            {
                return null;
            }
            var tFrom = tFromTypeArgs[0];
            var tTo = tToTypeArgs[0];
            if (tFrom == tTo && (tFrom.IsValueType || mappingConfig.GetRootMappingOperation(tFrom, tTo).ShallowCopy))
           {
               return new CustomConverterDescriptor
                {
                    ConversionMethodName = "Convert",
                    ConverterImplementation = typeof(GenericIEnumerableConverter_OneTypes<>),
                    ConverterClassTypeArguments = new[] { tFrom }
                };
            }

            return new CustomConverterDescriptor
            {
                ConversionMethodName = "Convert",
                ConverterImplementation = typeof(GenericIEnumerableConverter_DifferentTypes<,>),
                ConverterClassTypeArguments = new[] { tFrom, tTo }
            }; 
        }
    }


class GenericIEnumerableConverter_DifferentTypes<TFrom, TTo> : ICustomConverter
    {
        private Func<TFrom, TTo> _converter;
        public IEnumerable<TTo> Convert(IEnumerable<TFrom> from, object state)
        {
            if (from == null)
            {
                return null;
            } 

            TTo[] result = new TTo[from.Count()];
            int idx = 0;
            foreach (var f in from)
            {
                result[idx++] = _converter(f);
            }

            return result;
        } 

        public void Initialize(Type from, Type to, MapConfigBaseImpl mappingConfig)
        {
            var staticConverters = mappingConfig.GetStaticConvertersManager() ?? StaticConvertersManager.DefaultInstance;

            var staticConverterMethod = staticConverters.GetStaticConverter(typeof(TFrom), typeof(TTo));

           if (staticConverterMethod != null)
            {
                _converter = (Func<TFrom, TTo>)Delegate.CreateDelegate(
                    typeof(Func<TFrom, TTo>),
                    null,
                    staticConverterMethod
                );
            }
            else
            {
                _subMapper = ObjectMapperManager.DefaultInstance.GetMapperImpl(typeof(TFrom), typeof(TTo), mappingConfig);

                _converter = ConverterBySubmapper;
            }
        } 

        ObjectsMapperBaseImpl _subMapper;

        private TTo ConverterBySubmapper(TFrom from)
        {
            return (TTo)_subMapper.Map(from);
        }
    }


class GenericIEnumerableConverter_OneTypes<T>
    {

        public IEnumerable<T> Convert(IEnumerable<T> from, object state)
        {
            if (from == null)
          {
                return null;
            }

            return from;
        }
    }

此代码只是一个尽可能少适应的副本可以应用于具有多层次结构的对象。

您可以使用以下命令使用上述代码：

  new DefaultMapConfig().ConvertGeneric(
    typeof(IEnumerable<>),
    typeof(IEnumerable<>),
    new GenericIEnumerableConverterProvider());

这节省了我的一天，我也希望能救你的！呵呵呵

EmitMapper的集合列表映射问题

2 个答案: