asp.net-mvc - asp .net mvc 自定义模型绑定失败

Question

我写了一个自定义活页夹，但我似乎无法让它运行。这是我的代码：

 public abstract class SlideItem
{
   public string PlaceHolderName { get; set; }
    public uint PlaceHolderID { get; set; }
    public uint ItemType { get; set; }
}

public class TitleSlideItem : SlideItem
    {
       ...

        public TitleSlideItem()
        {
            ItemType = 1;
        }
    }



public class ParagraphSlideItem : SlideItem
{
     ...
     public ParagraphSlideItem()
    {
        ItemType = 2;
    }
}

 public class SlideItemBinder : IModelBinder

{
    public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {

        System.Diagnostics.Trace.WriteLine("BindModel is working");

        var values = (ValueProviderCollection)bindingContext.ValueProvider;
        var placeHolderName = (string)values.GetValue("PlaceHolderName").ConvertTo(typeof(string));
        var placeHolderID = (uint)values.GetValue("PlaceHolderID").ConvertTo(typeof(uint));
        var itemType = (uint)values.GetValue("ItemType").ConvertTo(typeof(uint));
        switch (itemType)
        {
            case 1:
                System.Diagnostics.Trace.WriteLine("TitleSlideItemBinder");
                return (SlideItem)new TitleSlideItem { PlaceHolderName = placeHolderName };
            case 2:
                System.Diagnostics.Trace.WriteLine("ParagraphSlideItem");
                return (SlideItem)new ParagraphSlideItem { PlaceHolderName = placeHolderName };
            case 3:
                System.Diagnostics.Trace.WriteLine("TextSlideItem");
                return (SlideItem)new TextSlideItem { PlaceHolderName = placeHolderName };
            case 4:
                System.Diagnostics.Trace.WriteLine("PictureSlideItem");
                return (SlideItem)new PictureSlideItem { PlaceHolderName = placeHolderName };
            default:
                System.Diagnostics.Trace.WriteLine("this should never-ever-ever-ever happen");
                //this should never-ever-ever-ever happen
                return (SlideItem)new TextSlideItem { PlaceHolderName = placeHolderName };
        }           
    }
}

我将此添加到我的 global.asax.cs 中：

     ModelBinders.Binders.Add(new KeyValuePair<Type, IModelBinder>(typeof(SlideItem), new SlideItemBinder()));           

但是当我尝试运行它时：

 [System.Web.Http.HttpPost]
 public HttpResponseMessage Create(IList<SlideContent> l)
        {

... }

我仍然收到 System.MissingMethodException 说：无法创建抽象类

我哪里错了？

真挚地，

佐利

Answer 1

检查此链接。您可能会在此处找到解决方案：ASP.NET MVC 2 - 绑定到抽象模型

答案有一个自定义模型绑定器。