C# 从 MVVM 中的 DataGrid 或 ListBox 绑定到 SelectedItems

Bind to SelectedItems from DataGrid or ListBox in MVVM

提问by Omar Mir

Just doing some light reading on WPF where I need to bind the selectedItems from a DataGrid but I am unable to come up with anything tangible. I just need the selected objects.

只是在 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。我只需要选定的对象。

DataGrid:

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">

采纳答案by Omar Mir

This will work:

这将起作用：

MultiSelectorBehaviours.vb

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

IListItemConverter.vb

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

TwoListSynchronizer.vb

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

Then for the XAML:

然后对于 XAML：

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

And finally the VM:

最后是虚拟机：

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

Credit Goes to: http://blog.functionalfun.net/2009/02/how-to-databind-to-selecteditems.html

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

回答by devuxer

My original answer was wrong (you cannot bind to SelectedItemsbecause it is a read-only property).

我原来的答案是错误的（你不能绑定，SelectedItems因为它是一个只读属性）。

One fairly MVVM-friendly way to work around this is to bind to the IsSelectedproperty of DataGridRow.

要解决这种情况的一个相当MVVM友好的方式是绑定到IsSelected的财产DataGridRow。

You can set up the binding like this:

您可以像这样设置绑定：

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

Then you need to create a DocumentViewModelthat inherits from ViewModelBase(or whatever MVVM base class you are using) and has the properties of your Documentyou want to present in the DataGrid, as well as an IsSelectedproperty.

然后您需要创建一个DocumentViewModel继承自ViewModelBase（或您正在使用的任何 MVVM 基类）并具有Document您想要在 DataGrid 中显示的IsSelected属性以及一个属性。

Then, in your main view model, you create a List(Of DocumentViewModel)called DocumentViewModelsto bind your DataGridto. (Note: if you will be adding/removing items from the list, use an ObservableCollection(T)instead.)

然后，在您的主视图模型中，您创建一个List(Of DocumentViewModel)调用DocumentViewModels来绑定您DataGrid。（注意：如果您要从列表中添加/删除项目，请改用 an ObservableCollection(T)。）

Now, here's the tricky part. You need to hook into the PropertyChangedevent of each DocumentViewModelin your list, like this:

现在，这是棘手的部分。您需要挂钩列表PropertyChanged中每个事件的事件DocumentViewModel，如下所示：

For Each documentViewModel As DocumentViewModel In DocumentViewModels
    documentViewModel.PropertyChanged += DocumentViewModel_PropertyChanged
Next

This allows you to respond to changes in any DocumentViewModel.

这使您可以响应任何DocumentViewModel.

Finally, in DocumentViewModel_PropertyChanged, you can loop through your list (or use a Linq query) to grab the info for each item where IsSelected = True.

最后，在 中DocumentViewModel_PropertyChanged，您可以循环遍历您的列表（或使用 Linq 查询）以获取其中每个项目的信息IsSelected = True。

回答by Shakti Prakash Singh

I know this post is a little old and has been answered. But I came up with a non MVVM answer. Its easy and works for me. Add another DataGrid, assuming your Selected Collection is SelectedResults:

我知道这个帖子有点旧，已经得到了回答。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" >

And in code behind, add this to the Constructor:

在后面的代码中，将其添加到构造函数中：

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

回答by Brian Hinchey

With a bit of trickery you can extend the DataGrid to create a bindable version of the SelectedItemsproperty. My solution requires the binding to have Mode=OneWayToSourcesince I only want to read from the property anyway, but it mightbe possible to extend my solution to allow the property to be read-write.

通过一些技巧，您可以扩展 DataGrid 以创建该SelectedItems属性的可绑定版本。我的解决方案需要绑定，Mode=OneWayToSource因为无论如何我只想从属性中读取，但可能可以扩展我的解决方案以允许属性进行读写。

I assume a similar technique could be used for ListBox, but I haven't tried it.

我认为 ListBox 可以使用类似的技术，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);
    }
}

回答by Mihai

I have a solution for this using a workaround that fit my needs.

我有一个解决方案，使用适合我需要的解决方法。

Make an EventToCommandon the ListItemTemplateon MouseUpand as a CommandParametersend the SelectedItemscollection

做一个EventToCommand对ListItemTemplate上MouseUp，并作为CommandParameter发送的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>

That way you can have a command in the viewmodel that handles this or saves the selected items for later use. Have fun coding

这样你就可以在视图模型中有一个命令来处理这个或保存选定的项目以供以后使用。玩得开心编码

回答by Julio Nobre

I can assure you: SelectedItemsis indeed bindable as a XAML CommandParameter

我可以向你保证：SelectedItems确实可以作为 XAML CommandParameter绑定

After a lot of digging and googling, I have finally found a simple solution to this common issue.

经过大量的挖掘和谷歌搜索，我终于找到了这个常见问题的简单解决方案。

To make it work you must follow ALL the following rules:

要使其工作，您必须遵循以下所有规则：

1. Following Ed Ball's suggestion', on you XAML command databinding, define CommandParameterproperty BEFORE Commandproperty. This a very time-consuming bug.

   

2. Make sure your ICommand's CanExecuteand Executemethods have a parameter of objecttype. This way you can prevent silencedcast exceptions that occurs whenever databinding CommandParametertype does not match your command method's parameter type.

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

1. 遵循Ed Ball 的建议'，在 XAML 命令数据绑定上，定义CommandParameter属性 BEFORE Command属性。这是一个非常耗时的错误。

   

2. 确保您的ICommand的CanExecute和Execute方法具有对象类型的参数。这样就可以防止沉默，每当发生数据绑定转换异常CommandParameter类型不匹配您的命令方法的参数类型。

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

For example, you can either send a listview/listbox's SelectedItemsproperty to you ICommandmethods or the listview/listbox it self. Great, isn't it?

例如，您可以将列表视图/列表框的SelectedItems属性发送给您的ICommand方法或列表视图/列表框本身。很棒，不是吗？

Hope it prevents someone spending the huge amount of time I did to figure out how to receive SelectedItemsas CanExecuteparameter.

希望它可以防止有人花费大量时间来弄清楚如何将SelectedItems作为CanExecute参数接收。

回答by Parrhesia Joe

I came here for the answer and I got a lot of great ones. I combined them all into an attached property, very similar to the one offered by Omar above, but in one class. Handles INotifyCollectionChanged and switching the list out. Doesn't leak events. I wrote it so it would be pretty simple code to follow. Written in C#, handles listbox selectedItems and dataGrid selectedItems.

我来这里是为了答案，我得到了很多很棒的答案。我将它们全部组合成一个附属属性，与上面 Omar 提供的属性非常相似，但属于一个类。处理 INotifyCollectionChanged 并切换列表。不泄漏事件。我写了它，所以它会是非常简单的代码。用 C# 编写，处理列表框 selectedItems 和 dataGrid selectedItems。

This works on both DataGrid and ListBox.

这适用于 DataGrid 和 ListBox。

(I just learned how to use GitHub) GitHub https://github.com/ParrhesiaJoe/SelectedItemsAttachedWpf

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

To Use:

使用：

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

And here's the code. There is a little sample on Git.

这是代码。Git 上有一个小示例。

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;
        }
    }
 }

回答by user2304573

The solution mentioned by devuxer

devuxer 提到的解决方案

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

does not work when having large dataset. You will need to disable row virtualization, and that is exactly the case where you need it...

有大数据集时不起作用。您将需要禁用行虚拟化，而这正是您需要它的情况......

EnableRowVirtualization="False"

EnableRowVirtualization="False"

回答by Neil B

For me the easiest route was to populate the ViewModel property in the SelectionChanged event.

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);
}

回答by Harry von Borstel

What about using a converter?

使用转换器怎么样？

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

Use it in a DataGrid's ContextMenulike this:

使用它的DataGrid的ContextMenu是这样的：

       <DataGrid.ContextMenu>
            <ContextMenu>
                <MenuItem
                    CommandParameter="{Binding Path=MySelectedItems, Converter={StaticResource selectedItemsConverter}, Mode=OneWay, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}}"
                    Command="{Binding MyDoSomethingWithMySelectedItemsCommand}"
                    Header="Do Something...">
                </MenuItem>