Question

我在WPF中构建我的第一个MVVM应用程序。在这一刻，我试图通过双击列表框中的项目来举起活动。此事件由View处理，如下面的代码所示。

现在我想向ViewModel发送列表框中双击的项目索引。我该怎么做？

PS：ClassObject和ClassDiagram都是自定义类，它们具有相同的属性＆＃34; Name＆＃34;

查看

public partial class ProjectView : UserControl
    {
        public ProjectView()
        {
            InitializeComponent();
            this.DataContext = new ProjectViewModel();
        }

        public void listBoxProject_MouseDoubleClick(object sender,MouseButtonEventArgs e)
        {
            MessageBox.Show(listBoxProject.SelectedIndex.ToString()); //Send index to ViewModel
        }
    }

XAML

<ListBox x:Name="listBoxProject" ItemsSource="{Binding CollectionList}" HorizontalAlignment="Stretch" Margin="-1,32,-1,-1" VerticalAlignment="Stretch" Width="auto" Background="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"
            DisplayMemberPath="Name"
            SelectedValuePath="Name"
            >
    <ListBox.ItemContainerStyle>
        <Style TargetType="{x:Type ListBoxItem}" BasedOn="{StaticResource {x:Type ListBoxItem}}">
            <EventSetter Event="MouseDoubleClick" Handler="listBoxProject_MouseDoubleClick"/>
        </Style>
    </ListBox.ItemContainerStyle>
</ListBox>

视图模型

namespace VITUMLEditor.ViewModels
{
    public class ProjectViewModel:BaseViewModel
    {
        private readonly CompositeCollection collectionList = new CompositeCollection();

        public ICommand AddClassCommand
        {
            get { return new DelegateCommand(AddClass); }
        }

        public ICommand AddClassDiagramCommand
        {
            get { return new DelegateCommand(AddClassDiagram); }
        }

        private void AddClass()
        {
            collectionList.Add(new ClassObject("Class" + ClassObject.Key, VisibilityEnum.Public));
        }

        private void AddClassDiagram()
        {
            collectionList.Add(new ClassDiagram("ClassDiagram" + ClassDiagram.Key));
        }

        public CompositeCollection CollectionList
        {
            get { return collectionList; }
        }
    }
}

Answer 1

In principle, you should do this with a Command. But then you've got to write code to make the double click invoke the command. The following is simple enough, and good enough for a very great number of common cases. We have dozens of these in production code and they're causing us no pain, because the view-viewmodel relationships in question are all 1:1 and will remain so. Just bear in mind that it's Impure MVVM, and can arbitrarily limit your options down the line.

Add an appropriately-named and parametered method to the viewmodel:

distance

And call it from the view:

public void ActivateItem(object item)
{
    //  Better if these two classes share a common base class or interface with 
    //  a virtual function to be called in this case, but there I go ranting from 
    //  the pulpit again. 
    if (item is ClassObject)
    {
        //  Stuff
    }
    else if (item is ClassDiagram)
    {
        //  Other stuff
    }
}

MVVM查看事件到ViewModel

1 个答案: