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我在绑定方面遇到了一点问题。我想将 2 个按钮与SelectedItema绑定ListBox。

包含几个值并显示ListBox它们（姓名，年龄，...）。当用户选择 的一个条目时ListBox，应弹出 2 个按钮“删除”和“更改”（<- 可见），因此这意味着按钮可见性应与 的 绑定，SelectedItem并且ListBox位于 ListBox-Item 旁边（如 iPhone 的“删除”按钮）。

当我选择一个项目时，我的代码实际上使按钮可见，但问题是所有项目的所有按钮都是可见的！实际代码（需要修复）是这样的（可见性部分）：

<Button DataContext="{Binding DataContext, ElementName=Window}" FontSize="15" Grid.Row="0" Content="Delete" Visibility="{Binding Path=SelectedItem, Mode=OneWay, ElementName=lbuser, Converter={StaticResource VisibilityConverter}}" Command="{Binding Delete}"/>
<Button DataContext="{Binding DataContext, ElementName=Window}" FontSize="15" Grid.Row="1" Content="Change" Visibility="{Binding Path=SelectedItem, Mode=OneWay, ElementName=lbuser, Converter={StaticResource VisibilityConverter}}" Command="{Binding Change}" />

但是如果有人需要完整的代码，这里是：

<Grid Height="Auto">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="212"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="15"/>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
    <ListBox ScrollViewer.HorizontalScrollBarVisibility="Disabled" x:Name="lbuser" ItemsSource="{Binding Users, Mode=TwoWay}" ScrollViewer.VerticalScrollBarVisibility="Auto" Grid.ColumnSpan="2"  SelectedItem="{Binding MySelectedListView, Mode=TwoWay}" Height="390" Width="Auto" >
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="Auto"/>
                        <ColumnDefinition Width="*"/>
                    </Grid.ColumnDefinitions>

                    <Grid Grid.Column="0">
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="Auto"/>
                        </Grid.RowDefinitions>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="50"/>
                            <ColumnDefinition Width="50"/>
                            <ColumnDefinition Width="90"/>
                            <ColumnDefinition Width="15"/>
                            <ColumnDefinition Width="150"/>
                        </Grid.ColumnDefinitions>
                        <TextBlock Text="{Binding Path=Bezeichnung}" Grid.ColumnSpan="4" FontSize="22.5" FontWeight="ExtraBold"/>
                        <TextBlock Grid.Row="1" Text="Name"/>
                        <TextBlock Grid.Row="1" Grid.Column="1" Text="{Binding Path=Name}"/>
                        <TextBlock Grid.Row="1" Grid.Column="2" Text="Age"/>
                        <TextBlock Grid.Row="1" Grid.Column="4" Text="{Binding Path=Age, Converter={StaticResource EuroConverter}}"/>
                        <TextBlock Grid.Row="2" Text="E-Mail"/>
                        <TextBlock Grid.Row="2" Grid.Column="1" Text="{Binding Path=EMail}" Width="Auto"/>
                        <TextBlock Grid.Row="2" Grid.Column="2" Text="Phone"/>
                        <TextBlock Grid.Row="2" Grid.Column="4" Text="{Binding Path=Phone, Converter={StaticResource EuroConverter}}"/>
                        <TextBlock Grid.Row="3" Text="Born"/>
                        <TextBlock Grid.Row="3" Grid.Column="1" Text="{Binding Path=YearBorn}" Width="Auto"/>
                        <TextBlock Grid.Row="3" Grid.Column="2" Text="Birthplace"/>
                        <TextBlock Grid.Row="3" Grid.Column="4" Text="{Binding Path=Birthplace}"/>
                    </Grid>
                    <Grid Grid.Column="1">
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="Auto"/>
                        </Grid.RowDefinitions>

                    <Button DataContext="{Binding DataContext, ElementName=Window}" FontSize="15" Grid.Row="0" Content="Delete" Visibility="{Binding Path=SelectedItem, Mode=OneWay, ElementName=lbuser, Converter={StaticResource VisibilityConverter}}" Command="{Binding Delete}"/>
                    <Button DataContext="{Binding DataContext, ElementName=Window}" FontSize="15" Grid.Row="1" Content="Change" Visibility="{Binding Path=SelectedItem, Mode=OneWay, ElementName=lbuser, Converter={StaticResource VisibilityConverter}}" Command="{Binding Change}" />
                    </Grid>
                </Grid>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
</ListBox>
</Grid>

编辑：可见性转换器

public class VisibilityConverter : IValueConverter
{
    #region [ IValueConverter ]

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (value == null)
            return System.Windows.Visibility.Collapsed;

        return System.Windows.Visibility.Visible;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotSupportedException();
    }

    #endregion
}

该值是选定项，这意味着当 ListBox 有 2 个项目并且我单击一个项目时，VisibilityConverter 将被调用 4 次并将 Visibility 设置为 true。通过转换器的 4 次调用，该值始终是 SelectedItem。

4

1 回答 1

0

Try binding the visibility to MySelectedListView. That is the ViewModels property the selected item of the listbox is bound to. Then the value should be of the correct type.

<Button DataContext="{Binding DataContext, ElementName=Window}" FontSize="15" Grid.Row="0" Content="Delete" Visibility="{Binding Path=MySelectedListView, Mode=OneWay, Converter={StaticResource VisibilityConverter}}" Command="{Binding Delete}"/>

You should be able to omit DataContext="{Binding DataContext, ElementName=Window}" if you have not set the datacontext on a higher level.

Edit: Another option would be to bind to a ButtonVisibility property in the User view model class. In the MySelcetedListView setter set the value of the existing object to Collapsed or Hidden (whatever fits your need) and that of the new one to Visible. Binding would then be Visibility="{Binding ButtonVisibility}"

于 2013-06-04T13:47:33.280 回答