mvvm - 使用 MVVM 模式在 Telerik RadGridView 中查找选定项目

Question

我在我的应用程序中使用 Telerik RadGridView，它有一个 GridViewSelectColumn 项目，它允许我选择网格中的各种项目。我有一个操作此选择的按钮，但不确定如何获取所选项目的列表。问题是我在 Caliburn.Micro 中使用了 MVVM 模式。是否需要在 View 中找到控件并遍历选中项列表？对于一个简单的任务来说，这似乎需要做很多工作。我会很感激任何想法。

Answer 1

Telerik 的 RadGridView 的问题在于，它的 SelectedItem 集合是只读的，因此您不能将双向绑定(bind)到 SelectedItems。

解决方法是使用自定义行为在 RadGridView 和您的 ViewModels SelectedItem 集合之间进行同步

您可以使用此行为:

// Behavior for synchronizing a RadDataGrid's SelectedItems collection with a SelectedItems collection of the ViewModel (the Network)
// The problem is, that RadDataGrid.SelectedItems is a read-only collection and therefore cannot be used for two-way binding.

class SelectedSyncBehavior
    : Behavior<RadGridView>
{
    bool _collectionChangedSuspended = false;

    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.SelectedItems.CollectionChanged += GridSelectedItems_CollectionChanged;
    }

    /// <summary>
    /// Getter/Setter for DependencyProperty, bound to the DataContext's SelectedItems ObservableCollection
    /// </summary>
    public INotifyCollectionChanged SelectedItems
    {
        get { return (INotifyCollectionChanged)GetValue(SelectedItemsProperty); }
        set { SetValue(SelectedItemsProperty, value); }
    }

    /// <summary>
    /// Dependency Property "SelectedItems" is target of binding to DataContext's SelectedItems
    /// </summary>
    public static readonly DependencyProperty SelectedItemsProperty =
        DependencyProperty.Register("SelectedItems", typeof(INotifyCollectionChanged), typeof(SelectedSyncBehavior), new PropertyMetadata(OnSelectedItemsPropertyChanged));

    /// <summary>
    /// PropertyChanged handler for DependencyProperty "SelectedItems"
    /// </summary>
    private static void OnSelectedItemsPropertyChanged(DependencyObject target, DependencyPropertyChangedEventArgs args)
    {
        INotifyCollectionChanged collection = args.NewValue as INotifyCollectionChanged;
        if (collection != null)
        {
            // Hook to the Network's SelectedItems
            collection.CollectionChanged += (target as SelectedSyncBehavior).ContextSelectedItems_CollectionChanged;
        }
    }

    /// <summary>
    /// Will be called, when the Network's SelectedItems collection changes
    /// </summary>
    void ContextSelectedItems_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (_collectionChangedSuspended) return;    // Don't react recursively to CollectionChanged events

        _collectionChangedSuspended = true;

        // Select and unselect items in the grid
        if (e.NewItems != null)
            foreach (object item in e.NewItems)
                AssociatedObject.SelectedItems.Add(item);

        if (e.OldItems != null)
            foreach (object item in e.OldItems)
                AssociatedObject.SelectedItems.Remove(item);

        _collectionChangedSuspended = false;
    }

    /// <summary>
    /// Will be called when the GridView's SelectedItems collection changes
    /// </summary>
    void GridSelectedItems_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (_collectionChangedSuspended) return;    // Don't react recursively to CollectionChanged events

        _collectionChangedSuspended = true;

        // Select and unselect items in the DataContext
        if (e.NewItems != null)
            foreach (object item in e.NewItems)
                (SelectedItems as IList).Add(item);

        if (e.OldItems != null)
            foreach (object item in e.OldItems)
                (SelectedItems as IList).Remove(item);

        _collectionChangedSuspended = false;
    }

}

将此行为与 RadGridViews 一起使用，如下所示:

<i:Interaction.Behaviors>
   <behaviors:SelectedSyncBehavior SelectedItems="{Binding ViewModel.SelectedItems}" />
</i:Interaction.Behaviors>