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绑定到ObservableCollection时,如何使子树节点出现在WPF树视图中?

observablecollection treeview binding wpf c#

0

Edward Tanguay · 技术社区 · 15 年前

我该怎么办改变在下面的代码中, 儿童区 “节点显示为 第一节 和 第二节 :

下面的代码给出了一个XamlParseException。

XAML:

<Window x:Class="TestTr32322.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:TestTr32322"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <HierarchicalDataTemplate x:Key="sectionTemplate" 
            ItemsSource="{Binding ChildSections}"
            DataType="{x:Type local:Section}">
            <TextBlock Text="{Binding Title}" />
        </HierarchicalDataTemplate>
    </Window.Resources>
    <Grid>
        <TreeView ItemsSource="{Binding Sections}" 
                  ItemTemplate="{StaticResource sectionTemplate}">
        </TreeView>
    </Grid>
</Window>

代码落后:

using System.Windows;
using System.ComponentModel;
using System.Collections.ObjectModel;

namespace TestTr32322
{
    public partial class Window1 : Window, INotifyPropertyChanged
    {
        #region ViewModelProperty: Sections
        private ObservableCollection<Section> _sections = new ObservableCollection<Section>();
        public ObservableCollection<Section> Sections
        {
            get
            {
                return _sections;
            }

            set
            {
                _sections = value;
                OnPropertyChanged("Sections");
            }
        }
        #endregion

        public Window1()
        {
            InitializeComponent();
            DataContext = this;

            Sections = Section.GetSections();
        }

        #region INotifiedProperty Block
        public event PropertyChangedEventHandler PropertyChanged;

        protected void OnPropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;

            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion

    }

    public class Section
    {
        public string Title { get; set; }
        public string Description { get; set; }
        public ObservableCollection<Section> ChildSections { get; set; }

        public static ObservableCollection<Section> GetSections()
        {
            ObservableCollection<Section> sections = new ObservableCollection<Section>();

            {
                Section section = new Section();
                section.Title = "First Section";
                section.ChildSections.Add(new Section
                {
                    Title = "A Child Section",
                    Description = "this is the description",
                    ChildSections = new ObservableCollection<Section>()
                });
                sections.Add(section);
            }

            {
                Section section = new Section();
                section.Title = "Second Section";
                section.ChildSections.Add(new Section
                {
                    Title = "A Child  Section",
                    Description = "this is the description",
                    ChildSections = new ObservableCollection<Section>()
                });
                sections.Add(section);
            }

            return sections;
        }
    }

}

2 回复 | 直到 15 年前

1

Anvaka 15 年前

看起来你需要 HierarchicalDataTemplate . 他们在文章中有一个例子…

2

1

Community CDub 8 年前

看看这个 question 以及公认的答案。它也应该把你指向正确的方向。

基本思想是用itemssource属性定义层次结构数据模板,并使它们按类型匹配。

在你的情况下:

<HierarchicalDataTemplate DataType="{x:Type local:Section}" 
                          ItemsSource="{Binding ChildSection}">
    <TextBlock Text="{Binding Path=Title}" />
</HierarchicalDataTemplate>

编辑 : 在代码中,应在向集合添加值之前创建新集合:

// The new was missing and resulted in the end in your XAML Parse Exception
section.ChildSections = new ObservableCollection<Section>();
section.ChildSections.Add( /*... */);