TreeView 不显示存储在数据中的子项 [英] TreeView not displaying children stored in data
问题描述
在我的程序中，我有一个带有数据支持(视图模型和数据模型)的 TreeView.添加到 TreeView 的每个项目都会添加一个子项目，但由于某种原因，子项目在运行时没有反映.但是，我能够在调试过程中看到子项，并且 TreeView's 数据模型中的Children"属性在它的 setter 中包含 NotifyPropertyChange.
In my program I have a TreeView with data backings (View Model & Data Model). Each item added to the TreeView gets a child item added with it, but for some reason the children are not reflecting during run time. However, I am able to see the children during debugging and my "Children" property in the TreeView's data model includes NotifyPropertyChange in it's setter.
注意:之前我有一个类似的问题，即新添加的节点(这些子节点的父节点)也不会显示.此问题已通过在树的 xaml 中设置 DisplayMemberPath="DisplayName.Value" 得到纠正.
Note: Earlier I had a similar problem where newly added nodes (parents of these children) wouldn't be displayed either. This problem was corrected by setting DisplayMemberPath="DisplayName.Value" in the tree's xaml.
TreeView 的 xaml:
TreeView ItemsSource="{Binding UserControl_DataModel.TreeViewViewModel.ObservableCollection<TreeViewDataModel>}" DisplayMemberPath="DisplayName.Value".../>
这是创建新节点并将其添加到TreeView (TreeViewViewModel) 的地方:
This is where new nodes are created and added to the TreeView (TreeViewViewModel):
private TreeViewDataModel createNewNode(StringItem nodeName)
{
var newNode = new TreeViewDataModel ()
{
DisplayName = nodeName
};
newNode.Children.Add(new TreeViewDataModel () { DisplayName = nodeName});
return newNode;
}
public void addNewLocNode(StringItem nodeName)
{
TreeObservableCollection.Add(createNewNode(nodeName));
}
注意:StringItem 是一个自定义类.在StringItem 中，Value 返回项目的字符串值.(例如:StringItem.Value)
Note: StringItem is a custom class. In StringItem, Value returns the string value of the item. (Ex: StringItem.Value)
TreeViewDataModel 中的子属性:
Children property in TreeViewDataModel:
public ObservableCollection<TreeViewDataModel> Children
{
get { return _children ?? (_children = new ObservableCollection<TreeViewDataModel>()); }
set
{
_children = value;
NotifyPropertyChange(() => Children);
}
}
为什么我的 TreeView 中没有显示子节点，我该如何解决?
Why aren't the child nodes showing up in my TreeView, and how can I fix this?
推荐答案
你没有足够的代码让我知道你是如何设置的.我试图让它与你已经拥有的相似.不过我想你应该能够弄清楚.
You don't have enough code for me to know exactly how you have things set up. I tried to keep it similar to what you already have. I think you should be able to figure it out though.
截图:
XAML:
<Window x:Class="WpfApplication9.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:app="clr-namespace:WpfApplication9"
Title="MainWindow" Height="350" Width="525">
<Grid>
<TreeView ItemsSource="{Binding TreeObservableCollection}"> <!-- DisplayMemberPath="DisplayName.Value" - Can't set both DisplayMemberPath and ItemTemplate -->
<TreeView.ItemTemplate>
<HierarchicalDataTemplate DataType="{x:Type app:TreeViewDataModel}" ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding DisplayName.Value}" />
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
</Grid>
代码:
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace WpfApplication9
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public ObservableCollection<TreeViewDataModel> TreeObservableCollection { get; set; }
public MainWindow()
{
InitializeComponent();
TreeObservableCollection = new ObservableCollection<TreeViewDataModel>();
this.DataContext = this;
this.Loaded += MainWindow_Loaded;
}
void MainWindow_Loaded(object sender, RoutedEventArgs e)
{
addNewLocNode(new StringItem("A"));
addNewLocNode(new StringItem("B"));
addNewLocNode(new StringItem("C"));
addNewLocNode(new StringItem("D"));
}
private TreeViewDataModel createNewNode(StringItem nodeName)
{
var newNode = new TreeViewDataModel()
{
DisplayName = nodeName
};
newNode.Children.Add(new TreeViewDataModel() { DisplayName = nodeName });
return newNode;
}
public void addNewLocNode(StringItem nodeName)
{
TreeObservableCollection.Add(createNewNode(nodeName));
}
}
public class StringItem
{
public string Value { get; set; }
public StringItem(string val)
{
Value = val;
}
}
public class TreeViewDataModel : System.ComponentModel.INotifyPropertyChanged
{
public StringItem DisplayName { get; set; }
private ObservableCollection<TreeViewDataModel> _children;
public ObservableCollection<TreeViewDataModel> Children
{
get { return _children ?? (_children = new ObservableCollection<TreeViewDataModel>()); }
set
{
_children = value;
NotifyPropertyChange("Children");
}
}
private void NotifyPropertyChange(string name)
{
if (PropertyChanged != null)
PropertyChanged(this, new System.ComponentModel.PropertyChangedEventArgs(name));
}
#region INotifyPropertyChanged Members
public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;
#endregion
}
}
替代方式:
<Window x:Class="WpfApplication9.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:app="clr-namespace:WpfApplication9"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<HierarchicalDataTemplate DataType="{x:Type app:TreeViewDataModel}" ItemsSource="{Binding Children}">
<TextBlock Text="{Binding DisplayName.Value}" />
</HierarchicalDataTemplate>
</Window.Resources>
<Grid>
<TreeView ItemsSource="{Binding TreeObservableCollection}" />
</Grid>
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