listview mvvm中的WPF删除按钮

Question

我在listview中有一个按钮来删除所选项目.当我点击按钮RemoveSubjectCommand没有触发时.如果我把按钮放在列表视图之外它工作正常.这只是因为嵌套项目.我怎么解决这个问题？

<ListView HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
        HorizontalContentAlignment="Stretch" Grid.ColumnSpan="3" Grid.Row="2"
        ItemsSource="{Binding AssignedSubjects}">
    <ListView.ItemContainerStyle>
        <Style TargetType="ListViewItem">
            <Setter Property="HorizontalContentAlignment" Value="Center" />
        </Style>
    </ListView.ItemContainerStyle>
    <ListView.View>
        <GridView>
            <GridViewColumn Width="140" Header="Subjects" DisplayMemberBinding="{Binding Name}" />
            <GridViewColumn Width="auto">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <Button Content="X" Command="{Binding RemoveSubjectCommand}"  />
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
        </GridView>
    </ListView.View>
</ListView>

查看模型,

private ICommand removeSubjectCommand;
**
public ICommand RemoveSubjectCommand
{
    get { return removeSubjectCommand ?? (removeSubjectCommand = new RelayCommand(param => this.RemoveSubject(), null)); }
}
**
private void RemoveSubject()
{ ***
}

如果我下面的代码,它将正常工作.

<ListView.InputBindings>
    <KeyBinding Key="Delete" Command="{Binding RemoveSubjectCommand}" />
</ListView.InputBindings>

Answer 1

那是因为按钮的DataContext是ListBoxItem DataContext.所以你需要转到父ListView DataContext.

一种方法是给ListView一个名字,并用元素名绑定

<ListView Name="lv" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
        HorizontalContentAlignment="Stretch" Grid.ColumnSpan="3" Grid.Row="2"
        ItemsSource="{Binding AssignedSubjects}">
    <ListView.ItemContainerStyle>
        <Style TargetType="ListViewItem">
            <Setter Property="HorizontalContentAlignment" Value="Center" />
        </Style>
    </ListView.ItemContainerStyle>
    <ListView.View>
        <GridView>
            <GridViewColumn Width="140" Header="Subjects" DisplayMemberBinding="{Binding Name}" />
            <GridViewColumn Width="auto">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <Button Content="X" Command="{Binding ElementName=lv,Path=DataContext.RemoveSubjectCommand}"  />
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
        </GridView>
    </ListView.View>
</ListView>

Answer 2

您需要将Command绑定到使用FindAncestor.否则,它将尝试RemoveSubjectCommand使用ListViewItem的datacontext 绑定到a ,而不是ViewModel.

试试这个:

<Button Content="X" Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=ListView}, Path=DataContext.RemoveSubjectCommand}"  />