UWP TreeView-绑定后面的数据更新使“可扩展”图标消失 [英] UWP TreeView - Update of data behind a binding makes the Expandable icon to disappear
问题描述
使用TreeView，我有一个Patient结构：
With a TreeView I have a Patient structure:
private ObservableCollection<MTreeViewPaz> _Patients;
public ObservableCollection<MTreeViewPaz> Patients
{
get { return _Patients; }
private set { Set(ref _Patients, value); }
}
并绑定到树视图：
<winui:TreeView
x:Name="treeView"
Grid.Row="1"
Expanding="treeView_Expanding"
ItemInvoked="OnItemInvoked"
ItemTemplate="{StaticResource ItemTemplate}"
ItemsSource="{x:Bind Patients, Mode=OneWay}"
SelectionMode="Single" />
带有项目模板：
<DataTemplate x:Key="ItemTemplate" x:DataType="model:MTreeViewBase">
<winui:TreeViewItem IsExpanded="False" ItemsSource="{x:Bind Visits}">
<controls1:TreeViewControl Data="{x:Bind}" />
</winui:TreeViewItem>
</DataTemplate>
和CustomControl：
and CustomControl:
<UserControl
x:Class="TitoDoc2020.Views.TreeViewControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="using:TitoDoc2020.Views"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:model="using:TitoDoc2020.Models"
d:DesignHeight="300"
d:DesignWidth="400"
mc:Ignorable="d">
<UserControl.Resources>
<DataTemplate x:Name="PAZTemplate" x:DataType="model:MTreeViewPaz">
<StackPanel Orientation="Horizontal">
<FontIcon
Margin="{StaticResource XXSmallTopRightBottomMargin}"
FontFamily="{StaticResource SymbolThemeFontFamily}"
Glyph="" />
<TextBlock
Margin="{StaticResource XXSmallTopRightBottomMargin}"
VerticalAlignment="Center"
Text="{x:Bind Name}" />
</StackPanel>
</DataTemplate>
<DataTemplate x:Name="VisitTemplate" x:DataType="model:MTreeViewVisit">
<StackPanel Orientation="Horizontal">
<FontIcon
Margin="{StaticResource XXSmallTopRightBottomMargin}"
FontFamily="{StaticResource SymbolThemeFontFamily}"
Foreground="{x:Bind ImageColor}"
Glyph="{x:Bind ImageSrc}" />
<TextBlock
Margin="{StaticResource XXSmallTopRightBottomMargin}"
VerticalAlignment="Center"
Text="{x:Bind VisitDescr}" />
</StackPanel>
</DataTemplate>
</UserControl.Resources>
<Grid>
<ContentControl x:Name="MainContent" />
</Grid>
</UserControl>
然后我有4个AppBarTogleButton选择患者的排序顺序。
他们每个人都调用相同的过程：
I have then 4 AppBarTogleButton to select the sorting order of the Patients. Each of them invoke the same procedure:
private async void AppBarToggleButton_Checked(object sender, RoutedEventArgs e)
{
string sorting = await ApplicationData.Current.LocalSettings.ReadAsync<string>("TreeViewSort");
switch (((Windows.UI.Xaml.Controls.AppBarToggleButton)sender).Name)
{
case "DescDate":
if (sorting == "DescDate")
{
return;
}
AsceDate.IsChecked = false;
AsceAlph.IsChecked = false;
DescAlph.IsChecked = false;
break;
case "AsceDate":
if (sorting == "AsceDate")
{
return;
}
DescDate.IsChecked = false;
AsceAlph.IsChecked = false;
DescAlph.IsChecked = false;
break;
case "DescAlph":
if (sorting == "DescAlph")
{
return;
}
AsceDate.IsChecked = false;
DescDate.IsChecked = false;
AsceAlph.IsChecked = false;
break;
case "AsceAlph":
if (sorting == "AsceAlph")
{
return;
}
AsceDate.IsChecked = false;
DescDate.IsChecked = false;
DescAlph.IsChecked = false;
break;
default:
break;
}
await ApplicationData.Current.LocalSettings.SaveAsync("TreeViewSort", ((Windows.UI.Xaml.Controls.AppBarToggleButton)sender).Name);
_sorting = ((Windows.UI.Xaml.Controls.AppBarToggleButton)sender).Name;
await SortTreeAsync(false);
}
并在SortTreeAsync中：
and in the SortTreeAsync:
private async Task SortTreeAsync(bool setCheck)
{
ObservableCollection<MTreeViewPaz> _patients;
if (treeView.Visibility == Visibility.Collapsed)
{
return;
}
treeView.Visibility = Visibility.Collapsed;
switch (_sorting)
{
case "DescDate":
if (setCheck) DescDate.IsChecked = true;
Patients = new ObservableCollection<MTreeViewPaz>(
from i in Patients orderby i.Data descending, i.Cognome, i.Nome select i);
/* await treeView.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
Patients = _patients;
});
*/
break;
case "AsceDate":
if (setCheck) AsceDate.IsChecked = true;
Patients = new ObservableCollection<MTreeViewPaz>(
from i in Patients orderby i.Data, i.Cognome, i.Nome select i);
break;
case "DescAlph":
if (setCheck) DescAlph.IsChecked = true;
Patients = new ObservableCollection<MTreeViewPaz>(
from i in Patients orderby i.Cognome descending, i.Nome descending, i.Data descending select i);
break;
case "AsceAlph":
if (setCheck) AsceAlph.IsChecked = true;
Patients = new ObservableCollection<MTreeViewPaz>(
from i in Patients orderby i.Cognome, i.Nome, i.Data descending select i);
break;
default:
DescDate.IsChecked = true;
break;
}
treeView.Visibility = Visibility.Visible;
return;
}
我用新分类的病人更新了病人。
的问题是，我几次更改了排序顺序后，>扩展了叶子分配器：
I update the Patients with the new sorted one. The issue is that after I change the sorting order couple of time the > to expand the leafs disapper:
我检查了一下，数据结构是完全相同的（除了顺序）并纠正
I've checked and the data structure is absolutely identical (apart from the order) and correct
这怎么可能？
---其他信息---
--- Additional info ---
您可以看到子结构仍然存在
As you can see the child structure is still there
推荐答案
UWP TreeView-绑定后面的数据更新使Expandable图标消失
UWP TreeView - Update of data behind a binding makes the Expandable icon to disappear
请检查此行< winui：TreeViewItem IsExpanded = False ItemsSource = {x：Bind Visits}> ，您使用的是 x：绑定无法响应访问属性的OneTime模型已更改，请使用 OneWay 或对其进行编辑TwoWay 模型并请确保您已为 Visits 属性调用了OnPropertyChanged事件。
Please check this line <winui:TreeViewItem IsExpanded="False" ItemsSource="{x:Bind Visits}">, you used x:Bind OneTime model that will not response Visits property changed, please edit it with OneWay or TwoWay model and please sure you have call OnPropertyChanged event for Visits property.
< winui：TreeViewItem IsExpanded = False ItemsSource = {x：Bind Visits，Mode = OneWay}>
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