Question

使用Visual Studio 2013和Window Phone 8 SDK我无法获得SelectedItem的{{1}}属性来正确绑定到MVVM属性。

对于在控件中包含但存在于SDK中但存在标记为已修复的错误，该问题似乎是一个相同的问题。 http://silverlight.codeplex.com/workitem/9360

是否有其他人遇到此问题且知道修复/更新版本？

我目前正在使用解决方法背后的代码

LongListSelector

Answer 1

要获取选择的项目到ViewModel，我总是使用LongListSelector扩展 - 代码可以在这里找到：https://gist.github.com/Depechie/7524630

您需要做的是将其添加到LongListSelector的XAML中：

<phone:LongListSelector x:Name="List" ext:LongListSelectorExtension.Command="{Binding *YOURVIEWMODELCOMMAND*}" />

viewmodel上的命令将在LongListSelector上接收项源的对象类型

Answer 2

使用行为

public class LongListSelectedItemBehavior : Behavior<LongListSelector>
{
    public object SelectedItem
    {
        get { return (object)GetValue(SelectedItemProperty); }
        set { SetValue(SelectedItemProperty, value); }
    }

    // Using a DependencyProperty as the backing store for SelectedItem.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register("SelectedItem", typeof(object), typeof(LongListSelectedItemBehavior), new PropertyMetadata(null));


    protected override void OnAttached()
    {
        base.OnAttached();

        if (AssociatedObject != null)
        {
            AssociatedObject.SelectionChanged += AssociatedObject_SelectionChanged;
        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if (AssociatedObject != null)
        {
            AssociatedObject.SelectionChanged -= AssociatedObject_SelectionChanged;
        }
    }

    private void AssociatedObject_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
    {
        SelectedItem = AssociatedObject.SelectedItem;
    }

和XAML

    <phone:LongListSelector Margin="0,0,-22,0"
                                    ItemsSource="{Binding Items}">
                <i:Interaction.Behaviors>
                    <local:LongListSelectedItemBehavior SelectedItem="{Binding SelectedItem, Mode=TwoWay}" />
                </i:Interaction.Behaviors>
            </phone:LongListSelector>

无法将LongListSelector.SelectedItem绑定到MVVM属性

2 个答案: