Question

我设法创建了Command，如下所示：

代码隐藏

public static RoutedCommand GetValueCommand = new RoutedCommand();
private void ExecutedGetValueCommand(object sender, ExecutedRoutedEventArgs e)
{
    MessageBox.Show("Custom Command Executed");
    Button b = (sender) as Button;
    MessageBox.Show(b.CommandParameter.ToString());
}
private void CanExecuteGetValueCommand(object sender, CanExecuteRoutedEventArgs e)
{
    e.CanExecute = true;
}

XAML

<UserControl.CommandBindings>
    <CommandBinding Command="{x:Static local:ReturnsUserControl.GetValueCommand}"
                    Executed="ExecutedGetValueCommand"
                    CanExecute="CanExecuteGetValueCommand" />
</UserControl.CommandBindings>

<ListView>
    <ListView.View>
        <GridView>
            <GridViewColumn>
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal"
                                    VerticalAlignment="Center"
                                    HorizontalAlignment="Center">
                            <TextBlock Text="{Binding ProductDescription}"/>
                         </StackPanel>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
            <GridViewColumn>
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal"
                                    VerticalAlignment="Center"
                                    HorizontalAlignment="Center">
                            <TextBox x:Name="txtExchangeQuantity"
                                     Tag="{Binding ProductBarcode}"/>
                            <Button Content="Add"
                                    Tag="{Binding ProductBarcode}"
                                    Command="{x:Static local:ReturnsUserControl.GetValueCommand}"
                                     CommandParameter="{Binding Text,ElementName=txtExchangeQuantity}"/>
                         </StackPanel>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
        </GridView>
    </ListView.View>
</ListView>

当我点击按钮时，CommandParameter总是返回null，即使我在文本框中放了一些东西，我也确定该命令正常工作，因为Custom Command Executed显示了。

我想在这里实现的是获取与TextBox Tag Button值的Tag的值>（相同的条形码），因为TextBox和Button都有多个实例，Tag是唯一可以配对的实例。

Answer 1

正如我们在评论中所说的那样，您应该寻找ExecutedRoutedEventArgs.Parameter而不是检查事件处理程序中的sender。

使用CommandParameter时，TextBox的Text属性返回null

1 个答案: