.NET WinForms DataBinding - BindingList< IBindableItem>其中IBindableItem的一些实现也可以实现IList

问题描述

这与，不幸的是我很难总结我的题目中的问题 - 所以请与我一起。

我创建了一个名为的数据库类，它实现了一个 ITreeItem 接口，并从 BindingList< ITreeItem> 。我有一个第二个课程， TreeLeaf ，它是树中的一个叶子，一个不能包含更多子项的终端。

意图是能够将数据绑定到文件夹，并具有数据绑定步行文件夹（和n级子文件夹）和树叶的树。然而，数据绑定不会下降到文件夹的底层BindingList中，因此文件夹在数据绑定时似乎没有子项目。

到目前为止，数据绑定正在使用文件夹作为 ITreeItem ，这是正确的，没有意识到文件夹是除了 ITreeItem 的实例之外的任何东西。 / p>

我的问题是：我如何暴露数据绑定文件夹是 ITreeItem ，也是 BindingList< ITreeItem> 的后代;或者如何钩住数据绑定，以帮助它走下结构？

以下是到目前为止的实现示例：

 使用System.ComponentModel; 
使用System.Windows.Forms; 
 
命名空间TreeData 
 {
 public interface ITreeItem 
 {
 string Name {get;组; 
 
 
 class TreeLeaf：ITreeItem 
 {
 public TreeLeaf（string name）
 {
 Name = name; 
} 
 
 public string Name {get;组; } 
} 
 
 class文件夹：BindingList< ITreeItem>，ITreeItem 
 {
 public Folder（string name）
 {
 Name = name ; 
} 
 
 public string Name {get;组; 
 
 
 class示例
 {
 public Example（）
 {
 var rootFolder = new Folder（Root）; 
 var subFolder1 = new Folder（Folder1）; 
 var subFolder2 = new Folder（Folder2）; 
 
 rootFolder.Add（subFolder1）; 
 rootFolder.Add（subFolder2）; 
 
 subFolder1.Add（new TreeLeaf（Item1））; 
 subFolder1.Add（new TreeLeaf（Item2））; 
 
 subFolder2.Add（new TreeLeaf（Item3））; 
 subFolder2.Add（new TreeLeaf（Item4））; 
 
 var treeDataSource = new BindingSource（）; 
 treeDataSource.DataSource = rootFolder; 
 
 //为了我的目的，'bindableControl'是
 // Infragistics UltraTree或UltraGrid。 
 //bindableControl.DataSource = treeDataSource; 
} 
} 
} 
  

解决方案

您可能需要考虑使用儿童属性？

  public class文件夹：ITreeItem 
 {
 public Folder（string name）
 {
 Name = name; 
 Children = new BindingList< ITreeItem>（）; 
} 
 
 public string Name {get;组; } 
 
 public BindingList< ITreeItem>孩子{get;私人集合} 
} 
  

This is related to another question of mine, and unfortunately I'm having a difficult time summarizing the issue in my Title--so please bear with me.

I've created a databindable class called Folder which implements a ITreeItem interface and inherits from BindingList<ITreeItem>. I have a second class, TreeLeaf, which is a leaf in the tree, a terminus that can't contain more child items.

The intent is to be able to databind to a Folder and have databinding walk the tree of folders (and n-level subfolders) and leafs. The databinding, however, doesn't descend into the underlying BindingList of a Folder, and as a result the Folder is appearing to not have child items when databound.

So far it looks like databinding is working with the folder as an instace of ITreeItem, which is correct, and not realizing that the Folder is anything other than an instance of ITreeItem.

My question is: how can I either expose to databinding that a folder is both an implementation of ITreeItem and also a descendant of BindingList<ITreeItem>; or how can I hook into the databinding to help it walk down the structure?

Here is a sample of the implementation so far:

using System.ComponentModel;
using System.Windows.Forms;

namespace TreeData
{
    public interface ITreeItem
    {
        string Name { get; set; }
    }

    class TreeLeaf : ITreeItem
    {
        public TreeLeaf(string name)
        {
            Name = name;
        }

        public string Name { get; set; }
    }

    class Folder : BindingList<ITreeItem>, ITreeItem
    {
        public Folder(string name)
        {
            Name = name;
        }

        public string Name { get; set; }
    }

    class Example
    {
        public Example()
        {
            var rootFolder = new Folder("Root");
            var subFolder1 = new Folder("Folder1");
            var subFolder2 = new Folder("Folder2");

            rootFolder.Add(subFolder1);
            rootFolder.Add(subFolder2);

            subFolder1.Add(new TreeLeaf("Item1"));
            subFolder1.Add(new TreeLeaf("Item2"));

            subFolder2.Add(new TreeLeaf("Item3"));
            subFolder2.Add(new TreeLeaf("Item4"));

            var treeDataSource = new BindingSource();
            treeDataSource.DataSource = rootFolder;

            // For my purposes the 'bindableControl' is
            // an Infragistics UltraTree or UltraGrid.
            //bindableControl.DataSource = treeDataSource;
        }
    }
}

解决方案

You might want to consider having a Children property instead?

public class Folder : ITreeItem
{
    public Folder(string name)
    {
        Name = name;
        Children = new BindingList<ITreeItem>();
    }

    public string Name { get; set; }

    public BindingList<ITreeItem> Children { get; private set; }
}

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