XAML 中的强制绑定更新

Question

我有一个带有列表框的视图和几个绑定到列表框中显示的对象的属性的文本框。打开时，列表框填充了数据，并且我在样式中有以下内容，以确保在有项目但未选择任何项目时选择第一个项目。

    <Style.Triggers>
        <MultiTrigger>
            <MultiTrigger.Conditions>
                <Condition Property="SelectedItem" Value="{x:Null}"/>
                <Condition Property="HasItems" Value="True"/>
            </MultiTrigger.Conditions>
            <Setter Property="SelectedIndex" Value="0"/>
        </MultiTrigger>
    </Style.Triggers>

这有效。填充列表时，始终会选择列表中的第一项。

不幸的是，即使选择了第一个项目，绑定到 selectedItems 属性的文本框（通过其父网格数据上下文）似乎也没有收到通知。

任何人都知道强制更新的方法（如果可能的话，使用 XAML）。目前，绑定如下所示：

<TextBox Text="{Binding Weight, ConverterParameter=\{0:F\}, Converter={StaticResource FormattingConverter}, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" />

编辑

下面是显示使用 PackageList SelectedItem 作为其数据上下文的网格 PackageDetailsGrid 的 XAML：

<StackPanel Orientation="Vertical" d:LayoutOverrides="Height">
    <TextBlock Text="Packages" Style="{DynamicResource TitleText}"/>
    <ListBox x:Name="PackageList" Style="{StaticResource SnazzyList}" FocusVisualStyle="{x:Null}" Margin="0" ItemsSource="{Binding Source={StaticResource Packages}}" HorizontalContentAlignment="Stretch" Height="132.5" Background="#18000000">
    </ListBox>
    <Grid Margin="0,0,8,0">
        <Button Content="Add" Margin="20,0,0,0" Width="87" HorizontalAlignment="Left" Style="{DynamicResource ClearButton}" Command="{Binding AddPackageCommand}" Visibility="{Binding ShipmentRecord.TransitStatus, Converter={StaticResource ShippedToVisibilityConverter}}"/>
        <Button Content="Delete" Margin="0,0,20,0" Style="{DynamicResource ClearButton}" HorizontalAlignment="Right" Width="87" Height="21.4666666666667" Command="{Binding DeletePackageCommand}" CommandParameter="{Binding SelectedItem, ElementName=PackageList, Mode=Default}" Visibility="{Binding ShipmentRecord.TransitStatus, Converter={StaticResource ShippedToVisibilityConverter}}"/>
    </Grid>
</StackPanel>
<Grid x:Name="PackageDetailsGrid" Margin="0" Grid.Column="1" DataContext="{Binding Items.CurrentItem, ElementName=PackageList, Mode=Default}">
    <StackPanel Margin="0">
        <Grid Margin="0,0,0,8">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="40*"/>
                <ColumnDefinition Width="60*"/>
            </Grid.ColumnDefinitions>
            <TextBlock Text="Dimensions" Foreground="White" FontWeight="Bold"/>
            <StackPanel Grid.Column="1" Orientation="Horizontal" d:LayoutOverrides="Height">
                <TextBox Text="{Binding Height, ConverterParameter=\{0:F\}, Converter={StaticResource FormattingConverter}, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" Width="48" TextWrapping="Wrap" Margin="0" HorizontalAlignment="Left" IsEnabled="{Binding CanEnterPackageDetails}">
                    <i:Interaction.Behaviors>
                        <local:SelectAllOnFocusTextboxBehavior/>
                    </i:Interaction.Behaviors>
                </TextBox>
                <TextBlock Text="X" Style="{DynamicResource XTextBlockStyle}"/>
                <TextBox Text="{Binding Width, ConverterParameter=\{0:F\}, Converter={StaticResource FormattingConverter}, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" Width="48" TextWrapping="Wrap" Margin="0" HorizontalAlignment="Left" IsEnabled="{Binding CanEnterPackageDetails}">
                    <i:Interaction.Behaviors>
                        <local:SelectAllOnFocusTextboxBehavior/>
                    </i:Interaction.Behaviors>
                </TextBox>
                <TextBlock Text="X" Style="{DynamicResource XTextBlockStyle}"/>
                <TextBox Text="{Binding Length, ConverterParameter=\{0:F\}, Converter={StaticResource FormattingConverter}, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" Width="48" TextWrapping="Wrap" Margin="0" HorizontalAlignment="Left" IsEnabled="{Binding CanEnterPackageDetails}">
                    <i:Interaction.Behaviors>
                        <local:SelectAllOnFocusTextboxBehavior/>
                    </i:Interaction.Behaviors>
                </TextBox>
            </StackPanel>
        </Grid>
    </StackPanel>
</Grid>

Answer 1

下面是 TextBox 的一些 xaml，其 Text 属性绑定到列表视图的 SelectedItem 属性。它包括用于在未选择任何内容时自动选择第一项的代码。

这是您正在寻找的解决方案吗？如果没有，我需要更多信息，即您正在处理的所有相关代码。

<StackPanel>
    <TextBox Text="{Binding SelectedItem, ElementName=MyListView}" />

    <ListView x:Name="MyListView">
        <ListView.Style>
            <Style TargetType="ListView">
                <Style.Triggers>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="SelectedItem" Value="{x:Null}"/>
                            <Condition Property="HasItems" Value="True"/>
                        </MultiTrigger.Conditions>
                        <Setter Property="SelectedIndex" Value="0"/>
                    </MultiTrigger>
                </Style.Triggers>
            </Style>
        </ListView.Style>

        <ListView.Items>
            <System:String>hello</System:String>
            <System:String>world</System:String>
        </ListView.Items>
    </ListView>
</StackPanel>