将项绑定到WPF树视图不会显示任何内容

本文关键字：显示 任何内 视图 绑定 WPF | 更新日期: 2023-09-27 18:18:00

为什么当我在xaml中设置了itemsource时，我的wpf树视图不显示内容?只有当我在CS文件中使用

设置此属性时，才会显示数据
trvFamilies.ItemsSource = families;

它可能不更新，因为我没有触发和更新在某种程度上在xaml?我不知道该怎么做才能让它正常工作。

ViewModel.cs 

using System;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Input;
namespace WpfApplication1
{
    public class ViewModel : ObservableObject
    {
        private ObservableCollection<Family> families; 
        public ObservableCollection<Family> Families
        {
            get { return families; }
            set
            {
                families = value;
                NotifyPropertyChanged("Families");
            }
        }
        public ViewModel()
        {
            // FAMILIES
            Family family1 = new Family() { Name = "The Doe's" };
            family1.Members.Add(new FamilyMember() { Name = "John Doe", Age = 42 });
            family1.Members.Add(new FamilyMember() { Name = "Jane Doe", Age = 39 });
            family1.Members.Add(new FamilyMember() { Name = "Sammy Doe", Age = 13 });
            Families.Add(family1);
            Family family2 = new Family() { Name = "The Moe's" };
            family2.Members.Add(new FamilyMember() { Name = "Mark Moe", Age = 31 });
            family2.Members.Add(new FamilyMember() { Name = "Norma Moe", Age = 28 });
            Families.Add(family2);
        }
    }
    public class Family
    {
        public Family()
        {
            this.Members = new ObservableCollection<FamilyMember>();
        }
        public string Name { get; set; }
        public ObservableCollection<FamilyMember> Members { get; set; }
    }
    public class FamilyMember
    {
        public string Name { get; set; }
        public int Age { get; set; }
    }
}

ObservableObject.cs 

using System;
using System.ComponentModel;
using System.Runtime.CompilerServices;
namespace WpfApplication1
{
    public class ObservableObject : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        public void NotifyPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}

MainWindow.xaml 

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:self="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="350" Width="300"
        WindowStartupLocation="CenterScreen">
    <Grid Margin="5">
        <TreeView Name="trvFamilies" ItemsSource="{Binding self:families}" Grid.Row="1" Grid.ColumnSpan="2">
            <TreeView.Resources>
                <HierarchicalDataTemplate DataType="{x:Type self:Family}" ItemsSource="{Binding Members}">
                    <StackPanel Orientation="Horizontal">
                        <Label VerticalAlignment="Center" FontFamily="WingDings" Content="1"/>
                        <TextBlock Text="{Binding Name}" />
                    </StackPanel>
                </HierarchicalDataTemplate>
                <DataTemplate DataType="{x:Type self:FamilyMember}">
                    <StackPanel Orientation="Horizontal">
                        <Label VerticalAlignment="Center" FontFamily="WingDings" Content="2"/>
                        <TextBlock Text="{Binding Name}" />
                    </StackPanel>
                </DataTemplate>
            </TreeView.Resources>
        </TreeView>
    </Grid>
</Window>

将项绑定到WPF树视图不会显示任何内容

当前绑定到一个公共字段:

  public List<Family> families

但是绑定源(数据)需要是一个公共属性。对于集合类型，在WPF中通常使用ObservableCollection

所以把你的属性改成:

public ObservableCollection<Family> Families { get; set; }


附加信息:

通常你绑定到的属性不驻留在视图类中(这里:不在你的窗口中)，而是在一个叫做"视图模型"的单独的类中，它应该实现INotifyPropertyChanged接口。

查看此处获取更多信息:Model-View-ViewModel-MVVM-Explained

最后，您的视图模型应该是这样的: 
public ObservableCollection<Family> Families
{
    get { return _families; }
    set
    {
        _families= value;
        RaisePropertyChanged("Families");
    }
}
public ObservableCollection<Family> _families; 
protected void RaisePropertyChanged(string propertyName)
{
    PropertyChangedEventHandler handler = PropertyChanged;
    if (handler != null)
    {
        handler(this, new PropertyChangedEventArgs(propertyName));
    }
}
public event PropertyChangedEventHandler PropertyChanged;
新的视图模型类就位后，绑定可以更改为 
ItemsSource="{Binding Families}"

最后你需要设置你的新视图模型类为DataContext在你的窗口，见这里

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