Question

在运行以下程序时，我正在获取

构图保持不变。由于以下错误，更改被拒绝：组合产生单个组合错误。根本原因如下。查看CompositionException.Errors属性以获取更多详细信息。

1）找不到与约束'（（exportDefinition.ContractName ==“System.Collections.Generic.IEnumerable（MEF.IToolWindow）”）AndAlso（exportDefinition.Metadata.ContainsKey（“ExportTypeIdentity”）AndAlso匹配的有效导出“System.Collections.Generic.IEnumerable（MEF.IToolWindow）”。Equals（exportDefinition.Metadata.get_Item（“ExportTypeIdentity”））））'，无效导出可能已被拒绝。

导致：无法在“MEF.Program + Application”部分设置导入'MEF.Program + Application.ToolWindows（ContractName =“System.Collections.Generic.IEnumerable（MEF.IToolWindow）”）'。元素：MEF.Program + Application.ToolWindows（ContractName =“System.Collections.Generic.IEnumerable（MEF.IToolWindow）”） - ＆gt; MEF.Program +应用

代码在这里

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel.Composition;
using System.ComponentModel.Composition.Primitives;
using System.ComponentModel.Composition.Hosting;
using System.Collections;

//Without MEF
namespace MEF
{
    public interface IToolWindow
    {
        string Name { get; set; }
    }
    public interface IMenuService
    {
        IMenu GetMenu(string menuName);
    }

    public interface IMenuItem
    {
        string Name { get; set; }
        string Title { get; set; }
        Action Handler { get; set; }
    }

    public interface IMenu
    {
        string Name { get; set; }
        string Title { get; set; }
        string ToolWindow { get; set; }
        IEnumerable<IMenuItem> Items { get; set; }
        IMenuItem GetItem(string itemName);
    }

    //public interface IMenuItem<> :IMenuItem{}
class Program
{
    static void Main(string[] args)
    {
        var container = new CompositionContainer();
        var compositionBatch = new CompositionBatch();

        var someToolWindow = new SomeToolWindow();
        var application = new Application();
        var menuService = new MenuService();

        compositionBatch.AddPart(application);
        compositionBatch.AddPart(someToolWindow);
        compositionBatch.AddPart(menuService);


        container.Compose(compositionBatch);

        //application.ToolWindows = new List<IToolWindow>{someToolWindow};
        //someToolWindow.MenuService = menuService;


        foreach(var window in application.ToolWindows)
            Console.WriteLine(window.Name);
        Console.WriteLine(someToolWindow.MenuService);
        Console.ReadLine();
    }



    public class Application
    {
        [Import]
        public IEnumerable<IToolWindow> ToolWindows{get;set;}

        public IToolWindow GetWindow(string windowName)
        {
            return ToolWindows.Where(w =>w.Name == windowName).FirstOrDefault();
        }
    }

    [Export(typeof(IToolWindow))]
    public class SomeToolWindow : IToolWindow
    {
        [Import]
        public IMenuService MenuService { get; set; }
        public string Name { get; set; }
        public string Title { get; set; }

    }

    [Export(typeof(IMenuService))]
    public class MenuService:IMenuService
    {
        public IEnumerable<IMenu> Menus {get;set;}
        public IMenu  GetMenu(string menuName)
        {
            return Menus.Where(m => m.Name == menuName).FirstOrDefault();
        }
    }
}

}

任何人都有想法？

Answer 1

如果要填充列表，则需要将[导入]更改为[ImportMany]。我测试了下面的代码并且它有效。

   public class Application
   {
       [ImportMany]
       public IEnumerable<IToolWindow> ToolWindows { get; set; }

       public IToolWindow GetWindow(string windowName)
       {
           return ToolWindows.Where(w => w.Name == windowName).FirstOrDefault();
       }
   }

如果您想要打印它，还需要为SomeToolWindow添加名称。

获取错误没有找到与约束匹配的有效导出

1 个答案: