得到更新,我有一个很大的问题,递归treeview不更新任何孩子的,如果我binding了的ItemSource(observablecollection)与converter。 我编写了一个小示例WPF应用程序来解释刺激性行为。的ObservableCollection与转换器中的TreeView不WPF
首先我有一个名为Folder的类。文件夹的集合是从真正的应用程序中的DataLayer提供的。下面是简单的示例类:
// Represents a Folder from the database
public class Folder
{
public string Label { get; set; }
// Data recursion
public ObservableCollection<Folder> Children { get; set; }
public Folder()
{
Children = new ObservableCollection<Folder>();
}
}
在表示层中,我需要更多属性才能在树视图中查看它。我无法改变Folder类。
// Hold additional data to a Folder
public class TreeViewFolder
{
public Folder Folder { get; set; }
public bool IsExpanded { get; set; }
}
我在我的例子中有一个ViewModel类,它生成一些根级别的测试数据。通过一个任务,模拟3秒后测试数据的变化:添加一个根和一个子文件夹。
// ViewModel to MainWindow.xaml
public class ViewModel
{
public ObservableCollection<Folder> Folders { get; set; }
public ObservableCollection<TreeViewFolder> TreeViewFolders { get; set; }
public ViewModel()
{
// childfolder
var childs = new ObservableCollection<Folder>();
childs.Add(new Folder{Label="3.1"});
// Generate some test data
Folders = new ObservableCollection<Folder>
{
new Folder {Label = "1."},
new Folder {Label = "2."},
new Folder {Label = "3.", Children = childs},
new Folder {Label = "4."}
};
// Add the test data to new TreeViewFolders
TreeViewFolders = new ObservableCollection<TreeViewFolder>
{
new TreeViewFolder{Folder = Folders[0]},
new TreeViewFolder{Folder = Folders[1]},
new TreeViewFolder{Folder = Folders[2]},
new TreeViewFolder{Folder = Folders[3]}
};
// This is the UI Thread
Execute.InitializeWithDispatcher();
// Wait for 3 seconds...
Task.Factory.StartNew(() =>
System.Threading.Thread.Sleep(3000))
// ...and then add a new main folder and one child folder
.ContinueWith((pre) =>
Execute.InvokeOnUIThread(() => {
Folders.Add(new Folder() {Label = "5."});
TreeViewFolders.Add(new TreeViewFolder{Folder = Folders[4]});
Folders[1].Children.Add(new Folder {Label = "2.1"});
}));
}
}
转换器实现的字典,以保持那些媒体链接一个TreeViewFolder所有文件夹的轨道,并能在一个文件夹或一个的ObservableCollection转换成TreeViewFolder或的ObservableCollection。未执行反向转换。
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
//DictionaryLookUp just holds a Folder <-> TreeViewFolder relation in a Dictionary<Folder, TreeViewFolder> for performance issues
// Single object
if (targetType == typeof(TreeViewFolder)) {
var inputFolder = value as Folder;
if (inputFolder == null) return null;
return DictionaryLookUp(inputFolder);
}
// Collection of Folders
// WPF SAYS IT WANTS AN IENUMERABLE??? I GIVE AN OBSERVABLECOLLECTION
if (targetType == typeof(IEnumerable)) {
var inputFolders = value as IEnumerable<Folder>;
if (inputFolders == null) return null;
var outputFolders = new ObservableCollection<TreeViewFolder>();
foreach (var folder in inputFolders) {
outputFolders.Add(DictionaryLookUp(folder));
}
return outputFolders;
}
//Error!
return null;
}
在MainWindow.xaml中,我只有两个TreeView。第一个是再次只是为了演示当我使用原始文件夹(不是TreeViewFolder)时一切正常。第二个TreeView是我需要它的。
<Window x:Class="TreeViewConverterBinding.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TreeViewConverterBinding"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<local:ViewModel />
</Window.DataContext>
<Window.Resources>
<local:FolderToTreeViewFolderConverter x:Key="FtTVFConverter" />
</Window.Resources>
<StackPanel >
<Label Content="TreeView for Folders: Binding without Converter" />
<TreeView ItemsSource="{Binding Folders}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate
DataType="{x:Type local:Folder}"
ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Label}"/>
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
<Label Content="TreeView for TreeViewFolders: Binding to same Source with Converter" />
<TreeView ItemsSource="{Binding TreeViewFolders}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate
DataType="{x:Type local:TreeViewFolder}"
ItemsSource="{Binding Folder.Children, Converter={StaticResource FtTVFConverter}}">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Folder.Label}"/>
<TextBlock Text=" Folder.Children.Count=" />
<TextBlock Text="{Binding Folder.Children.Count}"/>
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
</StackPanel>
</Window>
此外,我将一个特殊的TextBlock绑定到一个文件夹的子项的计数。
问题这里,在第二树视图TextBlock的显示计数= 1在条目中的后3秒“2”。但没有[+]出现在TreeView中。 [+]在条目“3”中。虽然。上层TreeView很棒!
谁能告诉我什么是这里的问题?我如何让[+]出现在底部TreeView的第二项中?
我知道有其他的方法与在TreeViewFolder属性(继承,反射,...),但不适合实际应用展开文件夹。 这里的主要问题是,一个文件夹只存在一次为整个应用程序,在这里,相应的TreeViewFolder存在具有不同特性的N次...
在此先感谢 罟
如果我使用icommand而不是你的task.factory来做你的添加文件夹的东西它为我工作。在这种情况下,我也摆脱了转换器。 – blindmeis
感谢您的意见。但我必须使用转换器,因为我需要TreeView的所有级别的TreeViewFolder实例。事实上,如果你只是在ItemSource绑定中删除了“,Converter = {StaticResource FtTVFConverter}”,那么我知道这一点。但这不是我所需要的... – Soko