CurrentPosition 属性未正确更新

Question

让我再试一次...这里是 XAML。您可以看到 CollectionViewSource、将其用作 DataContext 的 Grid、ListView 和 Delete 按钮。发生的事情是，当我单击 ListView 中的一行（并且触发样式触发器以选择 ListViewItem）时，该行被选中。当我单击删除按钮时，onclick 会触发，但 CurrentPosition 属性设置为 -1。是什么阻止了 CurrentPosition 属性被更新。

XAML

<Window x:Class="PretzelsUI.Admin.Ovens"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="" 
    Height="344" 
    Width="474" 
    mc:Ignorable="d" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:my="clr-namespace:Pretzels.Model;assembly=Pretzels.Model"
    ResizeMode="NoResize"
    WindowStartupLocation="CenterOwner"
    Background="{StaticResource WindowGradient}"       
    Loaded="Window_Loaded">
<Window.Resources>
    <CollectionViewSource x:Key="ovenViewSource" d:DesignSource="{d:DesignInstance my:Oven, CreateList=True}" />
</Window.Resources>
<Grid DataContext="{StaticResource ovenViewSource}">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <Border Grid.Row="0" BorderBrush="{StaticResource formTitleBorderBrush}" BorderThickness="2" Name="border1" CornerRadius="30" Padding="7" Background="{StaticResource formTitleBackgroundBrush}" VerticalAlignment="Center" Margin="11">
        <TextBlock Name="textBlock1" Text="Ovens" FontSize="18" FontWeight="Bold" Foreground="{StaticResource formTitleForegroundBrush}" />
    </Border>
    <ListView IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding}" Name="ovenListView" SelectionMode="Single" Height="177"  Grid.Row="1" TabIndex="2" Margin="5,5,5,0">
        <ListView.ItemContainerStyle>
            <Style TargetType="ListViewItem">
                <Setter Property="Control.HorizontalContentAlignment" Value="Stretch" />
                <Setter Property="Control.VerticalContentAlignment" Value="Stretch" />
                <!--<Style.Triggers>
                    <Trigger Property="IsKeyboardFocusWithin" Value="True">
                        <Setter Property="IsSelected" Value="True" />
                    </Trigger>
                </Style.Triggers>-->
            </Style>
        </ListView.ItemContainerStyle>
        <ListView.View>
            <GridView>                    
                <GridViewColumn x:Name="nameColumn" Header="Name" Width="100">
                    <GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <TextBox Margin="-6,-1" Text="{Binding Path=OvenName, Mode=TwoWay, ValidatesOnExceptions=true, NotifyOnValidationError=true, UpdateSourceTrigger=PropertyChanged}" Width="Auto" />
                        </DataTemplate>
                    </GridViewColumn.CellTemplate>
                </GridViewColumn>
                <GridViewColumn x:Name="descriptionColumn" Header="Description" Width="300">
                    <GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <TextBox Margin="-6,-1" Text="{Binding Path=OvenDescription, Mode=TwoWay, ValidatesOnExceptions=true, NotifyOnValidationError=true}" Width="Auto" MaxLength="100"/>
                        </DataTemplate>
                    </GridViewColumn.CellTemplate>
                </GridViewColumn>
            </GridView>
        </ListView.View>
    </ListView>
    <StackPanel Grid.Row="2" Name="stackPanel2" Margin="0,30,0,0" Orientation="Horizontal" VerticalAlignment="Center" HorizontalAlignment="Center">
        <Button Content="New" Height="23"  Margin="2,0,2,0" TabIndex="3" Name="btnAdd" Width="75" Click="btnInsrt_Click" />
        <Button Content="Save" Height="23" Margin="2,0,2,0" TabIndex="4" Name="btnSave" Width="75" Click="btnSave_Click" />
        <Button Content="Delete" Height="23" Margin="2,0,2,0" TabIndex="5" Name="btndelete" Width="75" Click="btndelete_Click" />
    </StackPanel>
</Grid>

C#

 public partial class Ovens : Window
{
    private PretzelEntities dbcontext = new PretzelEntities();
    //private OvenCollection EntityData;
    private CollectionViewSource ViewSource;
    private BindingListCollectionView OvenView;

    public Ovens()
    {
        InitializeComponent();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        ViewSource = (CollectionViewSource)this.FindResource("ovenViewSource");

        ViewSource.Source = from s in dbcontext.Ovens select s;
        OvenView = (BindingListCollectionView)(ViewSource.View);
    }


    private void btndelete_Click(object sender, RoutedEventArgs e)
    {
            if (OvenView.CurrentPosition > -1)
            {
                if (MessageBox.Show("Do you really want to delete this Oven?", "Delete Confirmation", MessageBoxButton.YesNo) == MessageBoxResult.Yes)
                {
                    this.OvenView.RemoveAt(this.OvenView.CurrentPosition);
                }
            }
            else
            {
                MessageBox.Show("Nothing to Delete.", "Error", MessageBoxButton.OK);
            }
    }




enter code here

---

我认为发生的情况是，当触发器触发 ListCollectionView 的 CurrentItem/CurrentPosition 时，没有正确更新。当我单击其中一行中的文本框时，我不确定是否手动执行此操作（尽管我知道可用的方法）。不知道该怎么做，我可能只是使用 VisualTreeHelper 手动定位选定的 ListViewItem。

Answer 1

我终于放弃了样式触发器，只为 ListView 行内的文本框/组合框处理了 GotFocus 事件。在处理程序中，我能够获取 ListViewItem 并将 IsSelected 设置为 true。像冠军一样工作。

private void TextBox_GotFocus(object sender, RoutedEventArgs e)
    {
        Control ctrl = sender as Control;
        ContentPresenter cp = (ContentPresenter)ctrl.TemplatedParent;
        GridViewRowPresenter gp = (GridViewRowPresenter)cp.Parent;
        Grid g = (Grid)gp.Parent;
        ListViewItem lvi = (ListViewItem)g.TemplatedParent;
        lvi.IsSelected = true;
    }

Answer 2

做了一些测试，问题出在样式触发器上。

<Trigger Property="IsKeyboardFocusWithin" Value="True">
                        <Setter Property="IsSelected" Value="True" />
                    </Trigger>

当我单击 ListViewItem 内的任何内容（即 TextBox/ComboBox）时，我正在使用样式触发器来选择 ListViewItem。当此触发器到位时，如果我选择一个 TextBox，则行选择，但 ListCollectionView 的 CurrentPosition 始终为 -1。如果我删除触发器并实际选择行本身（单击文本框外），则 CurrentPosition 设置正确。我的问题是为什么...我需要手动设置 CurrentPosition。任何帮助表示赞赏。

Answer 3

IMO，最好像这样在代码中设置这一切：

void InitializeDataContext()
{
    var ovens = (from s
                 in dbcontext.Ovens
                 select s).ToList();

    ICollectionView view = new CollectionViewSource
    {
        Source = ovens
    }.View;

    ViewSource = view;
    ovenListView.ItemsSource = ViewSource;
}

您可以在 Window_Loaded 中调用该方法，消除 Window_Loaded 中的其他代码，然后消除绑定，因为您已经在代码中完成了这一切。在视图 (MVVM) 中没有任何代码的情况下设置这一切确实会更好，但这超出了这个问题的范围。