使用AutoMapper展平嵌套列表

Question

我試圖在.NET 3.5中將嵌套對象展平為DTO對象。 到目前為止，我所看到的大部分內容都是使用AutoMapper來執行此操作（不幸的是，由於我需要使用.NET 3.5，因此使用v1.x）：

這是我的類結構的一段代碼：

public class RootObject
{
    [JsonProperty("BaseSupplier")]
    public BaseSupplier BaseSupplier { get; set; }

    [JsonProperty("BaseOrderShipmentLineitem")]
    public IList<BaseOrderShipmentLineitem> BaseOrderShipmentLineitem { get; set; }
}

public class BaseSupplier
{
    [JsonProperty("id")]
    public int Id { get; set; }

    [JsonProperty("name")]
    public string Name { get; set; }
}

public class BaseOrderShipmentLineitem
{
    [JsonProperty("id")]
    public int Id { get; set; }

    [JsonProperty("qty_delivered")]
    public int QtyDelivered { get; set; }

    [JsonProperty("BaseOrderLineitem")]
    public BaseOrderLineitem BaseOrderLineitem { get; set; }    
}

public class BaseOrderLineitem
{
    [JsonProperty("id")]
    public int Id { get; set; }

    [JsonProperty("product_sku")]
    public string ProductSku { get; set; }
}

public class ShipmentDetailsDTO
{
    public int BaseOrderShipmentLineitemId { get; set; }
    public string BaseSupplierName { get; set; }
    public string Sku { get; set; }
}

我一直在嘗試這樣的事情：

Mapper.CreateMap<BaseOrderLineitem, ShipmentDetailsDTO>()
    .ForMember(d => d.Sku, opts => opts.MapFrom(s => s.ProductSku));
Mapper.CreateMap<BaseOrderShipmentLineitem, ShipmentDetailsDTO>();
Mapper.CreateMap<RootObject, ShipmentDetailsDTO>()
    .ForMember(d => d.Sku, opts => opts.MapFrom(s => Mapper.Map<IEnumerable<BaseOrderLineitem>, IEnumerable<ShipmentDetailsDTO>>(s.BaseOrderShipmentLineitem.SelectMany(q => q.BaseOrderLineitem)).FirstOrDefault().Sku))
    ;

var model = Mapper.Map<IEnumerable<RootObject>, IEnumerable<ShipmentDetailsDTO>>(obj);

有了上面的代碼，我在s.BaseOrderShipmentLineitem.SelectMany(q => q.BaseOrderLineitem)上遇到了一個錯誤：

Cannot implicitly convert type 'IEnumerable<?>' to 'IEnumerable<BaseOrderLineitem>'. An explicit conversion exists (are you missing a cast?)

我不確定這只是我是否忽略的簡單事情。

Answer 1

一種簡單得多的方法是使用一些LINQ編寫一個簡單的擴展方法來自己進行投影。 它更簡單，更透明：

public static class MyConversionExtensions
{
    public static IEnumerable<ShipmentDetailsDTO> ToShipmentDetails(this RootObject root)
    {
        return root.BaseOrderShipmentLineitem.Select(x => new ShipmentDetailsDTO() {
            BaseOrderShipmentLineitemId = x.BaseOrderLineitem.Id,
            BaseSupplierName = root.BaseSupplier.Name,
            Sku = x.BaseOrderLineitem.ProductSku
        });
    }
}

用法：

var shipmentDetails = myRootObject.ToShipmentDetails();