c# - WPF 将 UI 事件绑定(bind)到 ViewModel 中的命令

Question

我正在对一个简单的应用程序进行一些重构以遵循 MVVM，我的问题是如何将 SelectionChanged 事件从我的代码中移到 viewModel 后面？我看过一些将元素绑定(bind)到命令的示例，但没有完全理解。任何人都可以协助解决这个问题。谢谢!

任何人都可以使用下面的代码提供解决方案吗？非常感谢!

public partial class MyAppView : Window 
{
    public MyAppView()
    {
        InitializeComponent();

        this.DataContext = new MyAppViewModel ();

        // Insert code required on object creation below this point.
    }

    private void contactsList_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
    {
        //TODO: Add event handler implementation here.           
        //for each selected contact get the labels and put in collection 

        ObservableCollection<AggregatedLabelModel> contactListLabels = new ObservableCollection<AggregatedLabelModel>();

        foreach (ContactListModel contactList in contactsList.SelectedItems)
        {
            foreach (AggregatedLabelModel aggLabel in contactList.AggLabels)
            {
                contactListLabels.Add(aggLabel);
            }
        }
        //aggregate the contactListLabels by name
        ListCollectionView selectedLabelsView = new ListCollectionView(contactListLabels);

        selectedLabelsView.GroupDescriptions.Add(new PropertyGroupDescription("Name"));
        tagsList.ItemsSource = selectedLabelsView.Groups;
    }
}

Answer 1

你应该使用 EventTrigger结合 InvokeCommandAction来自 Windows.Interactivity 命名空间。这是一个例子:

<ListBox ...>
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="SelectionChanged">
            <i:InvokeCommandAction Command="{Binding SelectedItemChangedCommand}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</ListBox>

可以引用System.Windows.Interactivity通过去 Add reference > Assemblies > Extensions .

还有完整的i命名空间是:xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" .