在XAML中强制绑定更新

Question

我有一个带有列表框和几个文本框的视图，这些文本框绑定到列表框中显示的对象的属性。在打开时，列表框中填充了数据，我在样式中有以下内容，以确保在有项目但没有选择任何项目时，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>

这是可行的。填充列表时，列表中的第一项始终处于选中状态。

不幸的是，即使选择了第一项，绑定到selectedItems属性的文本框(通过其父网格datacontext)似乎也没有收到通知。

任何人都知道有一种方法可以强制它们更新(如果可能的话，使用XAML )。目前，绑定是这样的：

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

编辑

下面的XAML显示了使用PackageList SelectedItem作为数据上下文的网格PackageDetailsGrid：

<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

下面是一个文本的xaml，它的TextBox属性被绑定到列表视图的SelectedItem属性。它包含用于在未选择任何内容时自动选择第一项的代码。

这就是你正在寻找的解决方案吗？如果没有，我需要更多的信息，也就是你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>