WPF TreeView - 如何绑定父/子类

Question

我有一个要绑定到 TreeView 的表。

NODE    NAME        PARENT
----    -----       -------
1       Bill        NULL
2       Jane        NULL
3       John        1
4       Mike        2
5       Bob         4
6       Jody        1
7       Larry       5
8       Heather     2
9       Steve       8

这是我的课：

public class Node
{
    public int ID { get; set; }
    public string Name { get; set; }
    public int? Parent { get; set; }

    public Node()
    {
    }

    public Node(int id, string name)
    {
        ID = id;
        Name = name;
        Parent = null;
    }

    public Node(int id, string name, int? parent)
    {
        ID = id;
        Name = name;
        Parent = parent;
    }

    public override string ToString()
    {
        return string.Format("[{0}] {1}", ID, Name);
    }

}

所以最终的结果应该是这样的：

---[1] Bill
  |-----[3] John
  |-----[4] Jody

---[2] Jane
  |-----[4] Mike
  |    |------[5] Bob
  |          |------[7] Larry
  |-----[8] Heather
       |------[9] Steve

目前我正在使用后面的代码构建它。 首先，我找到所有没有父项的项目。然后从代码中将它们添加到 TreeView：

    var TopNodes = Nodes.Where(n => n.Parent == null);

    foreach (Node n in TopNodes)
    {
        TreeViewItem newItem = new TreeViewItem();
        newItem.Tag = n.ID;
        newItem.Header = n.Name;

        newItem.Items.Add("..Loading..");
        tvTest.Items.Add(newItem);
    }

然后，当项目展开时，我填充父项，如下所示：

private void tvTest_Expanded(object sender, RoutedEventArgs e)
{
                item.Items.Clear();

        int parentID = (int)item.Tag;

        var children = Nodes.Where(x => x.Parent == parentID);

        foreach (Node n in children)
        {
            TreeViewItem newItem = new TreeViewItem();
            newItem.Tag = n.ID;
            newItem.Header = n.Name;

            newItem.Items.Add("..Loading..");
            item.Items.Add(newItem);
        }

}

如果我可以直接绑定这些数据，我觉得我会有更大的灵活性。尤其是当我开始着手对数据实施 CRUD 功能时。

感谢您给我的任何建议。

Answer 1

您可以使用 HierarchicalDataTemplate 实现此目的。

1. 修改您的 Node 类，使其包含一个名为 Children 的属性，类型为 List<Node>。这将包含该节点的所有子节点的列表。
2. 然后在您的视图模型中公开一个名为 TopNodes 的公共属性，类型为 List<Node>，它将返回顶级节点的列表。

3. 最后在xaml视图中，定义TreeView如下：

   <TreeView Name="TreeViewNodes" ItemsSource="{Binding TopNodes}">
       <TreeView.ItemTemplate>
           <HierarchicalDataTemplate DataType="{x:Type local:Node}" ItemsSource="{Binding Children}">
               <TextBlock Text="{Binding Path=Name}" />
           </HierarchicalDataTemplate>
       </TreeView.ItemTemplate>
   </TreeView>
   

您仍然必须从视图模型中相应地填充您的节点对象，但这样您就不必直接从视图模型中引用 TreeViewItem，因为这不是遵循 MVVM 模式时推荐的方式。

我希望这能回答你的问题:)

Answer 2

希望下面的例子对你有帮助

Xaml 前端

           <TreeView Grid.Row="1" Background="Transparent" ItemsSource="{Binding Directories}" Margin="0,10,0,0" Name="FolderListTreeView"
                Height="Auto" HorizontalAlignment="Stretch" Width="300"  local:ControlBehaviour.ControlEvent="TreeView.SelectedItemChanged" >
                <TreeView.Resources>
                    <HierarchicalDataTemplate DataType="{x:Type local:FileSystem}" ItemsSource="{Binding SubDirectories}">
                        <Label Content="{Binding Path= Name}" Name="NodeLabel" />
                    </HierarchicalDataTemplate>
                </TreeView.Resources>
            </TreeView>

包含子目录及其子目录的类

public class FileSystem :NotifyChange, IEnumerable
{
    #region Private members
    private ObservableCollection<FileSystem> subDirectoriesField;
    #endregion

    #region Public properties
    /// <summary>
    /// Gets and sets all the Files in the current folder
    /// </summary>
    public ObservableCollection<FileSystem> SubDirectories
    {
        get
        {
            return subDirectoriesField;
        }
        set
        {
            if (subDirectoriesField != value)
            {
                subDirectoriesField = value;
                RaisePropertyChanged("SubDirectories");
            }
        }
    }
    /// <summary>
    /// Gets or sets name of the file system 
    /// </summary>
    public string Name
    {
        get;
        set;
    }
    /// <summary>
    /// Gets or sets full path of the file system
    /// </summary>
    public string FullPath
    {
        get;
        set;
    }
    /// <summary>
    /// object of parent, null if the current node is root
    /// </summary>
    public FileSystem Parent
    {
        get;
        set;
    }
    public FileSystem(string fullPath, FileSystem parent)
    {
        Name = fullPath != null ? fullPath.Split(new char[] { System.IO.Path.DirectorySeparatorChar },
            StringSplitOptions.RemoveEmptyEntries).Last()
        FullPath = fullPath;
        Parent = parent;
        FileType = type;
        AddSubDirectories(fullPath);
    }

    public IEnumerator GetEnumerator()
    {
        return SubDirectories.GetEnumerator();
    }

    private void AddSubDirectories(string fullPath)
    {
        string[] subDirectories = Directory.GetDirectories(fullPath);
        SubDirectories = new ObservableCollection<FileSystem>();
        foreach (string directory in subDirectories)
        {
            SubDirectories.Add(new FileSystem(directory, this));
        }
    }
}

然后视图模型将如下所示

public class ViewModel:NotifyChange
{
   private ObservableCollection<FileSystem> directories;
   public ObservableCollection<FileSystem> Directories
    {
        get
        {
            return directoriesField;
        }
        set
        {
            directoriesField = value;
            RaisePropertyChanged("Directories");
        }
    }
    public ViewModel()
    {
       //The below code has to be moved to thread for better user expericen since when UI is loaded it might not respond for some time since it is looping through all the drives and it;s directories
       Directories=new  ObservableCollection<FileSystem>();
       Directories.Add(new FileSystem("C:\\", null);
       Directories.Add(new FileSystem("D:\\", null);
       Directories.Add(new FileSystem("E:\\", null);
    }
}

将 DataContext 设置为 ViewModel