从MVVM中的DataGrid或ListBox绑定到SelectedItems

Question

在底部看到我的答案

在WPF上做一些简单的阅读，我需要从DataGrid绑定selectedItems，但我无法想出任何有形的东西。我只需要选择的对象。

数据网格：

<DataGrid Grid.Row="5" 
    Grid.Column="0" 
    Grid.ColumnSpan="4" 
    Name="ui_dtgAgreementDocuments"
    ItemsSource="{Binding Path=Documents, Mode=TwoWay}"
    SelectedItem="{Binding Path=DocumentSelection, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
    HorizontalAlignment="Stretch" 
    VerticalAlignment="Stretch" 
    Background="White"
    SelectionMode="Extended" Margin="2,5" 
    IsReadOnly="True" 
    CanUserAddRows="False" 
    CanUserReorderColumns="False" 
    CanUserResizeRows="False"
    GridLinesVisibility="None" 
    HorizontalScrollBarVisibility="Hidden"
    columnHeaderStyle="{StaticResource GreenTea}" 
    HeadersVisibility="Column" 
    BorderThickness="2" 
    BorderBrush="LightGray" 
    CellStyle="{StaticResource NonSelectableDataGridCellStyle}"
    SelectionUnit="FullRow" 
    HorizontalContentAlignment="Stretch" AutoGenerateColumns="False">

Answer 1

我可以向您保证： SelectedItems 确实可绑定为XAML CommandParameter

经过大量的挖掘和谷歌搜索，我终于找到了解决这个常见问题的简单方法。

要使其有效，您必须遵循以下所有规则：

1. 关注Ed Ball's suggestion＆＃39;，在您的XAML命令数据绑定中，在命令属性之前定义 CommandParameter 属性。这是一个非常耗时的错误。

   

2. 确保 ICommand 的 CanExecute 和执行方法的参数为 object 类型。这样，只要数据绑定 CommandParameter 类型与命令方法的参数类型不匹配，就可以防止沉默强制转换异常。

   private bool OnDeleteSelectedItemsCanExecute(object SelectedItems)  
   {
       // Your code goes here
   }
   
   private bool OnDeleteSelectedItemsExecute(object SelectedItems)  
   {
       // Your code goes here
   }
   

例如，您可以将listview / listbox的 SelectedItems 属性发送给 ICommand 方法或自己的listview / listbox。太好了，不是吗？

希望它可以防止有人花费大量时间来确定如何将 SelectedItems 作为 CanExecute 参数接收。

Answer 2

我的原始回答是错误的（您无法绑定到SelectedItems，因为它是只读属性）。

一种解决MVVM问题的方法是绑定IsSelected的{​​{1}}属性。

您可以像这样设置绑定：

DataGridRow

然后，您需要创建一个继承自<DataGrid ItemsSource="{Binding DocumentViewModels}" SelectionMode="Extended"> <DataGrid.Resources> <Style TargetType="DataGridRow"> <Setter Property="IsSelected" Value="{Binding IsSelected}" /> </Style> </DataGrid.Resources> </DataGrid> （或您正在使用的任何MVVM基类）的DocumentViewModel，并具有您希望在DataGrid中显示的ViewModelBase的属性，以及Document属性。

然后，在您的主视图模型中，您创建一个名为IsSelected的{​​{1}}来绑定您的List(Of DocumentViewModel)。 （注意：如果您要添加/删除列表中的项目，请改用DocumentViewModels。）

现在，这是棘手的部分。您需要加入列表中每个DataGrid的{​​{1}}事件，如下所示：

ObservableCollection(T)

这使您可以回复任何PropertyChanged中的更改。

最后，在DocumentViewModel中，您可以遍历列表（或使用Linq查询）来获取For Each documentViewModel As DocumentViewModel In DocumentViewModels documentViewModel.PropertyChanged += DocumentViewModel_PropertyChanged Next 中每个项目的信息。

Answer 3

通过一些技巧，您可以扩展DataGrid以创建SelectedItems属性的可绑定版本。我的解决方案要求绑定具有Mode=OneWayToSource，因为我只想从属性读取，但可能可以扩展我的解决方案以允许该属性是读写。< / p>

我假设类似的技术可以用于ListBox，但我还没有尝试过。

public class BindableMultiSelectDataGrid : DataGrid
{
    public static readonly DependencyProperty SelectedItemsProperty =
        DependencyProperty.Register("SelectedItems", typeof(IList), typeof(BindableMultiSelectDataGrid), new PropertyMetadata(default(IList)));

    public new IList SelectedItems
    {
        get { return (IList)GetValue(SelectedItemsProperty); }
        set { throw new Exception("This property is read-only. To bind to it you must use 'Mode=OneWayToSource'."); }
    }

    protected override void OnSelectionChanged(SelectionChangedEventArgs e)
    {
        base.OnSelectionChanged(e);
        SetValue(SelectedItemsProperty, base.SelectedItems);
    }
}

Answer 4

我知道这篇文章有点陈旧，已经得到了解答。但我想出了一个非MVVM的答案。它很容易，对我有用。添加另一个DataGrid，假设您的Selected Collection是SelectedResults：

    <DataGrid x:Name="SelectedGridRows" 
        ItemsSource="{Binding SelectedResults,Mode=OneWayToSource}" 
        Visibility="Collapsed" >

在后面的代码中，将其添加到构造函数：

    public ClassConstructor()
    {
        InitializeComponent();
        OriginalGrid.SelectionChanged -= OriginalGrid_SelectionChanged;
        OriginalGrid.SelectionChanged += OriginalGrid_SelectionChanged;
    }
    private void OriginalGrid_SelectionChanged(object sender, 
        SelectionChangedEventArgs e)
    {
        SelectedGridRows.ItemsSource = OriginalGrid.SelectedItems;
    }

Answer 5

我来到这里寻找答案，我得到了很多很棒的答案。我将它们全部组合成一个附属的属性，非常类似于Omar提供的属性，但是在一个类中。处理INotifyCollectionChanged并将列表切换出来。不泄漏事件。我写了它，所以这将是非常简单的代码。用C＃编写，处理listbox selectedItems和dataGrid selectedItems。

这适用于DataGrid和ListBox。

（我刚学会了如何使用GitHub） GitHub https://github.com/ParrhesiaJoe/SelectedItemsAttachedWpf

使用：

<ListBox ItemsSource="{Binding MyList}" a:Ex.SelectedItems="{Binding ObservableList}" 
         SelectionMode="Extended"/>
<DataGrid ItemsSource="{Binding MyList}" a:Ex.SelectedItems="{Binding OtherObservableList}" />

这是代码。 Git上有一些小样本。

public class Ex : DependencyObject
{
    public static readonly DependencyProperty IsSubscribedToSelectionChangedProperty = DependencyProperty.RegisterAttached(
        "IsSubscribedToSelectionChanged", typeof(bool), typeof(Ex), new PropertyMetadata(default(bool)));
    public static void SetIsSubscribedToSelectionChanged(DependencyObject element, bool value) { element.SetValue(IsSubscribedToSelectionChangedProperty, value); }
    public static bool GetIsSubscribedToSelectionChanged(DependencyObject element) { return (bool)element.GetValue(IsSubscribedToSelectionChangedProperty); }

    public static readonly DependencyProperty SelectedItemsProperty = DependencyProperty.RegisterAttached(
        "SelectedItems", typeof(IList), typeof(Ex), new PropertyMetadata(default(IList), OnSelectedItemsChanged));
    public static void SetSelectedItems(DependencyObject element, IList value) { element.SetValue(SelectedItemsProperty, value); }
    public static IList GetSelectedItems(DependencyObject element) { return (IList)element.GetValue(SelectedItemsProperty); }

    /// <summary>
    /// Attaches a list or observable collection to the grid or listbox, syncing both lists (one way sync for simple lists).
    /// </summary>
    /// <param name="d">The DataGrid or ListBox</param>
    /// <param name="e">The list to sync to.</param>
    private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (!(d is ListBox || d is MultiSelector))
            throw new ArgumentException("Somehow this got attached to an object I don't support. ListBoxes and Multiselectors (DataGrid), people. Geesh =P!");

        var selector = (Selector)d;
        var oldList = e.OldValue as IList;
        if (oldList != null)
        {
            var obs = oldList as INotifyCollectionChanged;
            if (obs != null)
            {
                obs.CollectionChanged -= OnCollectionChanged;
            }
            // If we're orphaned, disconnect lb/dg events.
            if (e.NewValue == null)
            {
                selector.SelectionChanged -= OnSelectorSelectionChanged;
                SetIsSubscribedToSelectionChanged(selector, false);
            }
        }
        var newList = (IList)e.NewValue;
        if (newList != null)
        {
            var obs = newList as INotifyCollectionChanged;
            if (obs != null)
            {
                obs.CollectionChanged += OnCollectionChanged;
            }
            PushCollectionDataToSelectedItems(newList, selector);
            var isSubscribed = GetIsSubscribedToSelectionChanged(selector);
            if (!isSubscribed)
            {
                selector.SelectionChanged += OnSelectorSelectionChanged;
                SetIsSubscribedToSelectionChanged(selector, true);
            }
        }
    }

    /// <summary>
    /// Initially set the selected items to the items in the newly connected collection,
    /// unless the new collection has no selected items and the listbox/grid does, in which case
    /// the flow is reversed. The data holder sets the state. If both sides hold data, then the
    /// bound IList wins and dominates the helpless wpf control.
    /// </summary>
    /// <param name="obs">The list to sync to</param>
    /// <param name="selector">The grid or listbox</param>
    private static void PushCollectionDataToSelectedItems(IList obs, DependencyObject selector)
    {
        var listBox = selector as ListBox;
        if (listBox != null)
        {
            if (obs.Count > 0)
            {
                listBox.SelectedItems.Clear();
                foreach (var ob in obs) { listBox.SelectedItems.Add(ob); }
            }
            else
            {
                foreach (var ob in listBox.SelectedItems) { obs.Add(ob); }
            }
            return;
        }
        // Maybe other things will use the multiselector base... who knows =P
        var grid = selector as MultiSelector;
        if (grid != null)
        {
            if (obs.Count > 0)
            {
                grid.SelectedItems.Clear();
                foreach (var ob in obs) { grid.SelectedItems.Add(ob); }
            }
            else
            {
                foreach (var ob in grid.SelectedItems) { obs.Add(ob); }
            }
            return;
        }
        throw new ArgumentException("Somehow this got attached to an object I don't support. ListBoxes and Multiselectors (DataGrid), people. Geesh =P!");
    }
    /// <summary>
    /// When the listbox or grid fires a selectionChanged even, we update the attached list to
    /// match it.
    /// </summary>
    /// <param name="sender">The listbox or grid</param>
    /// <param name="e">Items added and removed.</param>
    private static void OnSelectorSelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        var dep = (DependencyObject)sender;
        var items = GetSelectedItems(dep);
        var col = items as INotifyCollectionChanged;

        // Remove the events so we don't fire back and forth, then re-add them.
        if (col != null) col.CollectionChanged -= OnCollectionChanged;
        foreach (var oldItem in e.RemovedItems) items.Remove(oldItem);
        foreach (var newItem in e.AddedItems) items.Add(newItem);
        if (col != null) col.CollectionChanged += OnCollectionChanged;
    }

    /// <summary>
    /// When the attached object implements INotifyCollectionChanged, the attached listbox
    /// or grid will have its selectedItems adjusted by this handler.
    /// </summary>
    /// <param name="sender">The listbox or grid</param>
    /// <param name="e">The added and removed items</param>
    private static void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        // Push the changes to the selected item.
        var listbox = sender as ListBox;
        if (listbox != null)
        {
            listbox.SelectionChanged -= OnSelectorSelectionChanged;
            if (e.Action == NotifyCollectionChangedAction.Reset) listbox.SelectedItems.Clear();
            else
            {
                foreach (var oldItem in e.OldItems) listbox.SelectedItems.Remove(oldItem);
                foreach (var newItem in e.NewItems) listbox.SelectedItems.Add(newItem);
            }
            listbox.SelectionChanged += OnSelectorSelectionChanged;
        }
        var grid = sender as MultiSelector;
        if (grid != null)
        {
            grid.SelectionChanged -= OnSelectorSelectionChanged;
            if (e.Action == NotifyCollectionChangedAction.Reset) grid.SelectedItems.Clear();
            else
            {
                foreach (var oldItem in e.OldItems) grid.SelectedItems.Remove(oldItem);
                foreach (var newItem in e.NewItems) grid.SelectedItems.Add(newItem);
            }
            grid.SelectionChanged += OnSelectorSelectionChanged;
        }
    }
 }

Answer 6

这将有效：

<强> MultiSelectorBehaviours.vb

Imports System.Collections
Imports System.Windows
Imports System.Windows.Controls.Primitives
Imports System.Windows.Controls
Imports System

Public NotInheritable Class MultiSelectorBehaviours
    Private Sub New()
    End Sub

    Public Shared ReadOnly SynchronizedSelectedItems As DependencyProperty = _
        DependencyProperty.RegisterAttached("SynchronizedSelectedItems", GetType(IList), GetType(MultiSelectorBehaviours), New PropertyMetadata(Nothing, New PropertyChangedCallback(AddressOf OnSynchronizedSelectedItemsChanged)))

    Private Shared ReadOnly SynchronizationManagerProperty As DependencyProperty = DependencyProperty.RegisterAttached("SynchronizationManager", GetType(SynchronizationManager), GetType(MultiSelectorBehaviours), New PropertyMetadata(Nothing))

    ''' <summary>
    ''' Gets the synchronized selected items.
    ''' </summary>
    ''' <param name="dependencyObject">The dependency object.</param>
    ''' <returns>The list that is acting as the sync list.</returns>
    Public Shared Function GetSynchronizedSelectedItems(ByVal dependencyObject As DependencyObject) As IList
        Return DirectCast(dependencyObject.GetValue(SynchronizedSelectedItems), IList)
    End Function

    ''' <summary>
    ''' Sets the synchronized selected items.
    ''' </summary>
    ''' <param name="dependencyObject">The dependency object.</param>
    ''' <param name="value">The value to be set as synchronized items.</param>
    Public Shared Sub SetSynchronizedSelectedItems(ByVal dependencyObject As DependencyObject, ByVal value As IList)
        dependencyObject.SetValue(SynchronizedSelectedItems, value)
    End Sub

    Private Shared Function GetSynchronizationManager(ByVal dependencyObject As DependencyObject) As SynchronizationManager
        Return DirectCast(dependencyObject.GetValue(SynchronizationManagerProperty), SynchronizationManager)
    End Function

    Private Shared Sub SetSynchronizationManager(ByVal dependencyObject As DependencyObject, ByVal value As SynchronizationManager)
        dependencyObject.SetValue(SynchronizationManagerProperty, value)
    End Sub

    Private Shared Sub OnSynchronizedSelectedItemsChanged(ByVal dependencyObject As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
        If e.OldValue IsNot Nothing Then
            Dim synchronizer As SynchronizationManager = GetSynchronizationManager(dependencyObject)
            synchronizer.StopSynchronizing()

            SetSynchronizationManager(dependencyObject, Nothing)
        End If

        Dim list As IList = TryCast(e.NewValue, IList)
        Dim selector As Selector = TryCast(dependencyObject, Selector)

        ' check that this property is an IList, and that it is being set on a ListBox
        If list IsNot Nothing AndAlso selector IsNot Nothing Then
            Dim synchronizer As SynchronizationManager = GetSynchronizationManager(dependencyObject)
            If synchronizer Is Nothing Then
                synchronizer = New SynchronizationManager(selector)
                SetSynchronizationManager(dependencyObject, synchronizer)
            End If

            synchronizer.StartSynchronizingList()
        End If
    End Sub

    ''' <summary>
    ''' A synchronization manager.
    ''' </summary>
    Private Class SynchronizationManager
        Private ReadOnly _multiSelector As Selector
        Private _synchronizer As TwoListSynchronizer

        ''' <summary>
        ''' Initializes a new instance of the <see cref="SynchronizationManager"/> class.
        ''' </summary>
        ''' <param name="selector">The selector.</param>
        Friend Sub New(ByVal selector As Selector)
            _multiSelector = selector
        End Sub

        ''' <summary>
        ''' Starts synchronizing the list.
        ''' </summary>
        Public Sub StartSynchronizingList()
            Dim list As IList = GetSynchronizedSelectedItems(_multiSelector)

            If list IsNot Nothing Then
                _synchronizer = New TwoListSynchronizer(GetSelectedItemsCollection(_multiSelector), list)
                _synchronizer.StartSynchronizing()
            End If
        End Sub

        ''' <summary>
        ''' Stops synchronizing the list.
        ''' </summary>
        Public Sub StopSynchronizing()
            _synchronizer.StopSynchronizing()
        End Sub

        Public Shared Function GetSelectedItemsCollection(ByVal selector As Selector) As IList
            If TypeOf selector Is MultiSelector Then
                Return TryCast(selector, MultiSelector).SelectedItems
            ElseIf TypeOf selector Is ListBox Then
                Return TryCast(selector, ListBox).SelectedItems
            Else
                Throw New InvalidOperationException("Target object has no SelectedItems property to bind.")
            End If
        End Function

    End Class
End Class

<强> IListItemConverter.vb

''' <summary>
''' Converts items in the Master list to Items in the target list, and back again.
''' </summary>
Public Interface IListItemConverter
    ''' <summary>
    ''' Converts the specified master list item.
    ''' </summary>
    ''' <param name="masterListItem">The master list item.</param>
    ''' <returns>The result of the conversion.</returns>
    Function Convert(ByVal masterListItem As Object) As Object

    ''' <summary>
    ''' Converts the specified target list item.
    ''' </summary>
    ''' <param name="targetListItem">The target list item.</param>
    ''' <returns>The result of the conversion.</returns>
    Function ConvertBack(ByVal targetListItem As Object) As Object
End Interface

<强> TwoListSynchronizer.vb

Imports System.Collections
Imports System.Collections.Specialized
Imports System.Linq
Imports System.Windows

''' <summary>
''' Keeps two lists synchronized. 
''' </summary>
Public Class TwoListSynchronizer
    Implements IWeakEventListener

    Private Shared ReadOnly DefaultConverter As IListItemConverter = New DoNothingListItemConverter()
    Private ReadOnly _masterList As IList
    Private ReadOnly _masterTargetConverter As IListItemConverter
    Private ReadOnly _targetList As IList


    ''' <summary>
    ''' Initializes a new instance of the <see cref="TwoListSynchronizer"/> class.
    ''' </summary>
    ''' <param name="masterList">The master list.</param>
    ''' <param name="targetList">The target list.</param>
    ''' <param name="masterTargetConverter">The master-target converter.</param>
    Public Sub New(ByVal masterList As IList, ByVal targetList As IList, ByVal masterTargetConverter As IListItemConverter)
        _masterList = masterList
        _targetList = targetList
        _masterTargetConverter = masterTargetConverter
    End Sub

    ''' <summary>
    ''' Initializes a new instance of the <see cref="TwoListSynchronizer"/> class.
    ''' </summary>
    ''' <param name="masterList">The master list.</param>
    ''' <param name="targetList">The target list.</param>
    Public Sub New(ByVal masterList As IList, ByVal targetList As IList)
        Me.New(masterList, targetList, DefaultConverter)
    End Sub

    Private Delegate Sub ChangeListAction(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))

    ''' <summary>
    ''' Starts synchronizing the lists.
    ''' </summary>
    Public Sub StartSynchronizing()
        ListenForChangeEvents(_masterList)
        ListenForChangeEvents(_targetList)

        ' Update the Target list from the Master list
        SetListValuesFromSource(_masterList, _targetList, AddressOf ConvertFromMasterToTarget)

        ' In some cases the target list might have its own view on which items should included:
        ' so update the master list from the target list
        ' (This is the case with a ListBox SelectedItems collection: only items from the ItemsSource can be included in SelectedItems)
        If Not TargetAndMasterCollectionsAreEqual() Then
            SetListValuesFromSource(_targetList, _masterList, AddressOf ConvertFromTargetToMaster)
        End If
    End Sub

    ''' <summary>
    ''' Stop synchronizing the lists.
    ''' </summary>
    Public Sub StopSynchronizing()
        StopListeningForChangeEvents(_masterList)
        StopListeningForChangeEvents(_targetList)
    End Sub

    ''' <summary>
    ''' Receives events from the centralized event manager.
    ''' </summary>
    ''' <param name="managerType">The type of the <see cref="T:System.Windows.WeakEventManager"/> calling this method.</param>
    ''' <param name="sender">Object that originated the event.</param>
    ''' <param name="e">Event data.</param>
    ''' <returns>
    ''' true if the listener handled the event. It is considered an error by the <see cref="T:System.Windows.WeakEventManager"/> handling in WPF to register a listener for an event that the listener does not handle. Regardless, the method should return false if it receives an event that it does not recognize or handle.
    ''' </returns>
    Public Function ReceiveWeakEvent(ByVal managerType As Type, ByVal sender As Object, ByVal e As EventArgs) As Boolean Implements System.Windows.IWeakEventListener.ReceiveWeakEvent
        HandleCollectionChanged(TryCast(sender, IList), TryCast(e, NotifyCollectionChangedEventArgs))

        Return True
    End Function

    ''' <summary>
    ''' Listens for change events on a list.
    ''' </summary>
    ''' <param name="list">The list to listen to.</param>
    Protected Sub ListenForChangeEvents(ByVal list As IList)
        If TypeOf list Is INotifyCollectionChanged Then
            CollectionChangedEventManager.AddListener(TryCast(list, INotifyCollectionChanged), Me)
        End If
    End Sub

    ''' <summary>
    ''' Stops listening for change events.
    ''' </summary>
    ''' <param name="list">The list to stop listening to.</param>
    Protected Sub StopListeningForChangeEvents(ByVal list As IList)
        If TypeOf list Is INotifyCollectionChanged Then
            CollectionChangedEventManager.RemoveListener(TryCast(list, INotifyCollectionChanged), Me)
        End If
    End Sub

    Private Sub AddItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
        Dim itemCount As Integer = e.NewItems.Count

        For i As Integer = 0 To itemCount - 1
            Dim insertionPoint As Integer = e.NewStartingIndex + i

            If insertionPoint > list.Count Then
                list.Add(converter(e.NewItems(i)))
            Else
                list.Insert(insertionPoint, converter(e.NewItems(i)))
            End If
        Next
    End Sub

    Private Function ConvertFromMasterToTarget(ByVal masterListItem As Object) As Object
        Return If(_masterTargetConverter Is Nothing, masterListItem, _masterTargetConverter.Convert(masterListItem))
    End Function

    Private Function ConvertFromTargetToMaster(ByVal targetListItem As Object) As Object
        Return If(_masterTargetConverter Is Nothing, targetListItem, _masterTargetConverter.ConvertBack(targetListItem))
    End Function

    Private Sub HandleCollectionChanged(ByVal sender As Object, ByVal e As NotifyCollectionChangedEventArgs)
        Dim sourceList As IList = TryCast(sender, IList)

        Select Case e.Action
            Case NotifyCollectionChangedAction.Add
                PerformActionOnAllLists(AddressOf AddItems, sourceList, e)
                Exit Select
            Case NotifyCollectionChangedAction.Move
                PerformActionOnAllLists(AddressOf MoveItems, sourceList, e)
                Exit Select
            Case NotifyCollectionChangedAction.Remove
                PerformActionOnAllLists(AddressOf RemoveItems, sourceList, e)
                Exit Select
            Case NotifyCollectionChangedAction.Replace
                PerformActionOnAllLists(AddressOf ReplaceItems, sourceList, e)
                Exit Select
            Case NotifyCollectionChangedAction.Reset
                UpdateListsFromSource(TryCast(sender, IList))
                Exit Select
            Case Else
                Exit Select
        End Select
    End Sub

    Private Sub MoveItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
        RemoveItems(list, e, converter)
        AddItems(list, e, converter)
    End Sub

    Private Sub PerformActionOnAllLists(ByVal action As ChangeListAction, ByVal sourceList As IList, ByVal collectionChangedArgs As NotifyCollectionChangedEventArgs)
        If sourceList Is _masterList Then
            PerformActionOnList(_targetList, action, collectionChangedArgs, AddressOf ConvertFromMasterToTarget)
        Else
            PerformActionOnList(_masterList, action, collectionChangedArgs, AddressOf ConvertFromTargetToMaster)
        End If
    End Sub

    Private Sub PerformActionOnList(ByVal list As IList, ByVal action As ChangeListAction, ByVal collectionChangedArgs As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
        StopListeningForChangeEvents(list)
        action(list, collectionChangedArgs, converter)
        ListenForChangeEvents(list)
    End Sub

    Private Sub RemoveItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
        Dim itemCount As Integer = e.OldItems.Count

        ' for the number of items being removed, remove the item from the Old Starting Index
        ' (this will cause following items to be shifted down to fill the hole).
        For i As Integer = 0 To itemCount - 1
            list.RemoveAt(e.OldStartingIndex)
        Next
    End Sub

    Private Sub ReplaceItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
        RemoveItems(list, e, converter)
        AddItems(list, e, converter)
    End Sub

    Private Sub SetListValuesFromSource(ByVal sourceList As IList, ByVal targetList As IList, ByVal converter As Converter(Of Object, Object))
        StopListeningForChangeEvents(targetList)

        targetList.Clear()

        For Each o As Object In sourceList
            targetList.Add(converter(o))
        Next

        ListenForChangeEvents(targetList)
    End Sub

    Private Function TargetAndMasterCollectionsAreEqual() As Boolean
        Return _masterList.Cast(Of Object)().SequenceEqual(_targetList.Cast(Of Object)().[Select](Function(item) ConvertFromTargetToMaster(item)))
    End Function

    ''' <summary>
    ''' Makes sure that all synchronized lists have the same values as the source list.
    ''' </summary>
    ''' <param name="sourceList">The source list.</param>
    Private Sub UpdateListsFromSource(ByVal sourceList As IList)
        If sourceList Is _masterList Then
            SetListValuesFromSource(_masterList, _targetList, AddressOf ConvertFromMasterToTarget)
        Else
            SetListValuesFromSource(_targetList, _masterList, AddressOf ConvertFromTargetToMaster)
        End If
    End Sub




    ''' <summary>
    ''' An implementation that does nothing in the conversions.
    ''' </summary>
    Friend Class DoNothingListItemConverter
        Implements IListItemConverter

        ''' <summary>
        ''' Converts the specified master list item.
        ''' </summary>
        ''' <param name="masterListItem">The master list item.</param>
        ''' <returns>The result of the conversion.</returns>
        Public Function Convert(ByVal masterListItem As Object) As Object Implements IListItemConverter.Convert
            Return masterListItem
        End Function

        ''' <summary>
        ''' Converts the specified target list item.
        ''' </summary>
        ''' <param name="targetListItem">The target list item.</param>
        ''' <returns>The result of the conversion.</returns>
        Public Function ConvertBack(ByVal targetListItem As Object) As Object Implements IListItemConverter.ConvertBack
            Return targetListItem
        End Function
    End Class

End Class

然后是XAML：

<DataGrid ..... local:MultiSelectorBehaviours.SynchronizedSelectedItems="{Binding SelectedResults}" />

最后是VM：

Public ReadOnly Property SelectedResults As ObservableCollection(Of StatisticsResultModel)
    Get
        Return _objSelectedResults
    End Get
End Property

信用转到：http://blog.functionalfun.net/2009/02/how-to-databind-to-selecteditems.html

Answer 7

我有一个解决方案，使用适合我需要的解决方法。

在EventToCommand上的ListItemTemplate上MouseUp和CommandParameter发送SelectedItems集合

 <i:Interaction.Triggers>
     <i:EventTrigger EventName="MouseUp">
         <helpers:EventToCommand Command="{Binding DataContext.SelectionChangedUpdate,
                                 RelativeSource={RelativeSource AncestorType=UserControl}}"
                                 CommandParameter="{Binding ElementName=personsList, Path=SelectedItems}" />
    </i:EventTrigger>                         
</i:Interaction.Triggers>

通过这种方式，您可以在viewmodel中拥有一个处理此命令的命令，或者保存所选项目供以后使用。 享受有趣的编码

Answer 8

对我来说，最简单的方法是在SelectionChanged事件中填充ViewModel属性。

private void MyDataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    (DataContext as MyViewModel).SelectedItems.Clear();
    foreach (var i in MyDataGrid.SelectedItems) (DataContext as MyViewModel).SelectedItems.Add(i as ItemType);
}

Answer 9

此问题在WPF问题队列中被标记为“增强”：

https://github.com/dotnet/wpf/issues/3140

---

也许最终将进行修复/更新，并立即提供解决方案。

Answer 10

使用转换器如何？

public class SelectedItemsConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var dg = value as DataGrid;
        return dg?.SelectedItems;
    }
...

像这样在DataGrid的{​​{1}}中使用它：

ContextMenu

Answer 11

直接绑定做视图模型，有点棘手的版本：​​

1）创建ICommand：

public class GetSelectedItemsCommand : ICommand
{
    public GetSelectedItemsCommand(Action<object> action)
    {
        _action = action;
    }

    private readonly Action<object> _action;

    public bool CanExecute(object parameter)
    {
        return true;
    }

    public event EventHandler CanExecuteChanged;

    public void Execute(object parameter)
    {
        _action(parameter);
    }
}

2）创建DataGrid

<DataGrid x:Name="DataGridOfDesperatePeople" SelectionMode="Extended">
    <i:Interaction.Triggers>
         <i:EventTrigger EventName="SelectionChanged">
              <i:InvokeCommandAction CommandParameter="{Binding ElementName=DataGridOfDesperatePeople, Path=SelectedItems}" Command="{Binding SelectedItemsCommand }" />
          </i:EventTrigger>
    </i:Interaction.Triggers>
</DataGrid>

3）在视图模型中创建

public List<YourClassOfItemInTheGrid> SelectedItems { get; set; }  = new List<YourClassOfItemInTheGrid>();

public ICommand SelectedItemsCommand
{
    get
    {
        return new GetSelectedItemsCommand(list =>
        {

            SelectedItems.Clear();
            IList items = (IList)list;
            IEnumerable<YourClassOfItemInTheGrid> collection = items.Cast<YourClassOfItemInTheGrid>();
            SelectedItems = collection.ToList();
        });
    }
}

Answer 12

这是一个简单的解决方案。这样，您可以将任何数据传递/更新到ViewModel

Designer.xaml

<DataGrid Grid.Row="1" Name="dgvMain" SelectionChanged="DataGrid_SelectionChanged" />

Designer.cs

ViewModel mModel = null;
public Designer()
{
    InitializeComponent();

    mModel = new ViewModel();
    this.DataContext = mModel;
}

private void DataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    mModel.SelectedItems = dgvMain.SelectedItems;
}

ViewModel.cs

public class ViewModel
{
    public IList SelectedItems { get; set; }
}

Answer 13

devuxer提到的解决方案

<DataGrid.Resources>
        <Style TargetType="DataGridRow">
            <Setter Property="IsSelected"
                    Value="{Binding IsSelected}" />
        </Style>
    </DataGrid.Resources>

拥有大型数据集时

不起作用。您将需要禁用行虚拟化，这正是您需要它的情况......

EnableRowVirtualization = “假”