如何在单击命令上设置文本框值

Question

在我的Resources.xaml（资源词典）上我有一个数据模板：

<DataTemplate x:Key="ProductDetailsContentTemplate">
    <StackPanel Orientation="Vertical" >
        <Viewbox Margin="27,0,28,0" Height="200" >
            <Image UWPUtil:ImageExtensions.CachedUriSource="{Binding ImageUri}" />
        </Viewbox>
        <TextBlock Text="Description" Style="{StaticResource CaptionTextBlockStyle}" FontWeight="Bold" FontSize="24"/>
        <TextBlock Text="{Binding ProductDescription}" Style="{StaticResource SubtitleTextBlockStyle}" FontSize="30"/>

        <TextBlock Text="Barcode" Style="{StaticResource CaptionTextBlockStyle}" FontWeight="Bold" FontSize="24"/>
        <TextBlock Text="{Binding Barcode}" Style="{StaticResource SubtitleTextBlockStyle}" FontSize="30"/>

        <TextBlock Text="Weight" Style="{StaticResource CaptionTextBlockStyle}" FontWeight="Bold" FontSize="24"/>
        <TextBlock Text="{Binding Weight}" Style="{StaticResource SubtitleTextBlockStyle}" FontSize="30"/>

        <TextBlock Text="Quantity" Style="{StaticResource CaptionTextBlockStyle}" FontWeight="Bold" FontSize="24"/>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="25*"/>
                <ColumnDefinition Width="50*"/>
                <ColumnDefinition Width="25*"/>
            </Grid.ColumnDefinitions>
            <Button x:Name="SubtractQytyButton" Grid.Column="0" Content="-" FontSize="24" HorizontalAlignment="Stretch"
                        Margin="5,0" Style="{StaticResource TestButtonStyle}" FontWeight="ExtraBold"
                        Click="SubQytyButton_Click"/>
            <TextBox x:Name="QuantityTextBox" Grid.Column="1" HorizontalAlignment="Stretch" FontSize="24" Margin="5,0"
                         KeyDown="Quantity_Keydown" TextChanging="Quantity_TextChanging"
                         Text="{Binding Quantity, Mode=TwoWay, Converter={StaticResource DecmialConverter}}" MaxLength="5" TextAlignment="Center"/>
            <Button  x:Name="AddQytyButton" Grid.Column="2" Content="+" FontSize="24" HorizontalAlignment="Stretch"
                         Margin="5,0" Style="{StaticResource TestButtonStyle}" FontWeight="ExtraBold"
                         Click="AddQytyButton_Click"/>
        </Grid>
    </StackPanel>
</DataTemplate><br>

我使用 Mads Kristensen 的 File Nesting 文件嵌套它，这是线程：https://marketplace.visualstudio.com/items?itemName=MadsKristensen.FileNesting

所以我的 ResourceDictionary 上有一个 Resources.xaml.cs 我的问题是我想在 AddQytyButton 和 SubQytyButton 单击命令上设置我的 QuantityTextBox 值，这是我的单击命令事件：

private void AddQytyButton_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
    {
        //does not exist in the current context
        QuantityTextBox.Text = "test";
    }

或

private void AddQytyButton_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
    {
        Button btn = sender as Button;
        // this is not working as null reference
        var textbox = (btn.Parent as StackPanel).Children[1] as TextBox;
    }

谢谢，
尼科廷

Answer 1

您应该将 btn.Parent 转换为 Grid 而不是 StackPanel，因为您在 XAML.

中使用前者

var textbox = (btn.Parent as Grid).Children[1] as TextBox;

如何在单击命令上设置文本框值

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