Wpf 如果ViewModel的IsSelected属性绑定到ListBox,则仅第一项选择有效?
我有一个会议视图模型列表绑定到数据网格。 每个会议视图模型都有一个文档视图模型列表绑定到DataGrid的DataGridTemplate列中的列表框 DocumentViewModel的IsSelected属性绑定到ListBox的Item属性IsSelected 我在输出控制台中没有发现绑定错误 DocumentViewModel中的“删除文档”按钮将检查其CanExecute方法:Wpf 如果ViewModel的IsSelected属性绑定到ListBox,则仅第一项选择有效?,wpf,listbox,viewmodel,selected,Wpf,Listbox,Viewmodel,Selected,我有一个会议视图模型列表绑定到数据网格。 每个会议视图模型都有一个文档视图模型列表绑定到DataGrid的DataGridTemplate列中的列表框 DocumentViewModel的IsSelected属性绑定到ListBox的Item属性IsSelected 我在输出控制台中没有发现绑定错误 DocumentViewModel中的“删除文档”按钮将检查其CanExecute方法: private bool CanDeleteDocument() {
private bool CanDeleteDocument()
{
return _isSelected;
}
当我在列表框中选择第一个项目时,删除按钮被启用。
当我在列表框中选择第二、第三等项目时,删除按钮始终处于禁用状态
我尝试只粘贴重要的代码,并剪切其他内容:
我刚刚尝试用一个列表框(不是DataGrid的一部分)重建场景,我得到了相同的行为:/
我很乐意听到任何提示:)
XAML:
<DataGrid VirtualizingStackPanel.VirtualizationMode="Recycling"
ScrollViewer.CanContentScroll="False"
CanUserResizeRows="True"
VerticalScrollBarVisibility="Auto"
ItemsSource="{Binding MeetingViewModelList}"
AutoGenerateColumns="False"
x:Name="DailyGrid"
Height="580"
SelectionMode="Single"
CanUserSortColumns="False"
Background="#FF2DCE2D"
CanUserAddRows="False"
HeadersVisibility="All"
RowHeaderWidth="40"
RowHeight="200" >
<!--Content-->
<DataGridTemplateColumn Width="0.5*" Header="Content">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Helper:RichTextBox LostFocus="RTFBox_LostFocus" VerticalScrollBarVisibility="Auto" x:Name="RTFBox" Text="{Binding Content,IsAsync=True}" AcceptsReturn="True" AutoWordSelection="False" AllowDrop="False" SelectionBrush="#FFAC5BCB" HorizontalScrollBarVisibility="Hidden">
<Helper:RichTextBox.TextFormatter>
<Helper:RtfFormatter />
</Helper:RichTextBox.TextFormatter>
</Helper:RichTextBox>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<!--Documents-->
<DataGridTemplateColumn Visibility="{Binding Source={StaticResource spy}, Path=DataContext.DocumentsVisible}" IsReadOnly="True" Width="125" Header="Attachments">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<StackPanel Background="Green" DataContext="{Binding DocumentViewModelList}" Orientation="Vertical" >
<ListBox SelectionMode="Single" VirtualizingStackPanel.IsVirtualizing="False"
Height="100"
Width="Auto"
Focusable="True"
ScrollViewer.HorizontalScrollBarVisibility="Auto"
ScrollViewer.VerticalScrollBarVisibility="Auto"
Grid.Row="1"
Name="documentListBox"
BorderThickness="1"
ItemsSource="{Binding}"
Visibility="{Binding ElementName=documentListBox,Path=HasItems, Converter={StaticResource boolToVisibilityConverter}}"
>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding Path=Name}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
<ListBox.ItemContainerStyle>
<Style TargetType="{x:Type ListBoxItem}">
<Setter Property="IsSelected" Value="{Binding Mode=TwoWay, Path=IsSelected}" />
</Style>
</ListBox.ItemContainerStyle>
</ListBox>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Stretch">
<Button Command="{Binding Path=DeleteDocumentCommand}" HorizontalAlignment="Stretch" Content="Delete" />
<Button Command="{Binding Path=AddDocumentCommand}" HorizontalAlignment="Stretch" Content="Add" />
<Button Command="{Binding Path=OpenDocumentCommand}" HorizontalAlignment="Stretch" Content="Open" />
</StackPanel>
</StackPanel>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
我确信它可以这样工作,但是用另一种方式跟踪所选项目不是更容易吗?例如,绑定到包装实际集合的ICollectionView(例如ListCollectionView)允许使用内置的选择跟踪机制(ICollectionView的CurrentItem)。或者,您可以使用列表框的SelectedValue和SelectedValuePath。我认为问题在于delete命令不知道选择已更改 将CanDeleteChanged添加到中继命令中,并在此之后将其提升。提升属性更改(“IsSelected”)。我以前在Prism应用程序中也遇到过类似的问题 编辑。事实上,您应该添加CanDeleteChanged并在其中放置一个断点,然后查看它是否在您期望的时候被调用 抱歉,我的意思是删除中继命令上的CanExecuteChanged事件。您的代码应该在某个地方声明了中继命令。为了信息起见,这里是 公共类中继命令:ICommand { #区域字段
readonly Action<object> _execute;
readonly Predicate<object> _canExecute;
#endregion // Fields
#region Constructors
public RelayCommand(Action<object> execute)
: this(execute, null)
{
}
public RelayCommand(Action<object> execute, Predicate<object> canExecute)
{
if (execute == null)
throw new ArgumentNullException("execute");
_execute = execute;
_canExecute = canExecute;
}
#endregion // Constructors
#region ICommand Members
[DebuggerStepThrough]
public bool CanExecute(object parameter)
{
return _canExecute == null ? true : _canExecute(parameter);
}
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public void Execute(object parameter)
{
_execute(parameter);
}
#endregion // ICommand Members
只读操作\u执行;
只读谓词_canExecute;
#endregion//字段
#区域构造函数
公共中继命令(操作执行)
:此(执行,空)
{
}
公共RelayCommand(操作执行,谓词canExecute)
{
if(execute==null)
抛出新的ArgumentNullException(“执行”);
_执行=执行;
_canExecute=canExecute;
}
#endregion//构造函数
#区域ICommand成员
[调试步骤至]
公共布尔CanExecute(对象参数)
{
返回_canExecute==null?true:_canExecute(参数);
}
公共事件事件处理程序CanExecuteChanged
{
添加{CommandManager.RequerySuggested+=value;}
删除{CommandManager.RequerySuggested-=value;}
}
public void Execute(对象参数)
{
_执行(参数);
}
#endregion//ICommand成员
}Hm。。。并不是说我现在想放弃这个想法,而是你说Alex是对的。我非常专注于使用ViewModel选择ISS。我现在做了如下操作:SelectedItem=“{Binding SelectedDocumentViewModel,Mode=TwoWay}”并且在DocumentViewModel:private bool CanDeleteDocument(){if(SelectedDocumentViewModel!=null)返回true;else返回false;}有效,但是我想知道为什么IsSelected不起作用!;-)我猜这是因为ListBoxItem的IsSelected属性是由ListBox在内部操纵的,这会干扰绑定,但我可能会偏离这一点。不太确定。对不起。。。但是如何将属性添加到RelayCommand?请给我一个代码片段,我不知道代码应该是什么样子。另一个问题是,尽管documentListBox是空的,但按钮已启用。。。我认为这个问题是由于删除按钮位于DocumentViewModel中。由于没有currentMeeting.DocumentList.Count>0,我可以绑定到,因为在加载整个会议时,我必须启用/禁用Delete按钮。我应该将删除按钮和其他按钮移动到控制器上,对吗?但即使这样,我在控制器上也只有一个按钮命令,但在视图中,我有10个会议,每个会议都有一个删除文档按钮。不工作…似乎我必须将按钮放在DocumentListViewModel中,就像它们在WAF for wpf中那样!?好的,我现在制作了DocumentListViewModel,它是一个多么痛苦的绑定尝试和错误。但现在我都在工作了!删除按钮被禁用如果文档列表是空的或者没有选择任何文档,我应该开始一个博客:PSorry最近几天都没有选中。对于CanDeleteChanged,您应该查看RelayCommand的构造函数参数。
public class MeetingViewModel: ViewModelBase
{
private ObservableCollection<DocumentViewModel> _documentViewModelList = new ObservableCollection<DocumentViewModel>();
private Meeting _meeting;
public MeetingViewModel(Meeting meeting)
{
_meeting= meeting;
_meeting.Documents.ForEach(doc => DocumentViewModelList.Add(new DocumentViewModel(doc)));
}
public ObservableCollection<DocumentViewModel> DocumentViewModelList
{
get { return _documentViewModelList; }
set
{
_documentViewModelList = value;
this.RaisePropertyChanged("DocumentViewModelList");
}
}
public string Content
{
get { return _meeting.Content; }
set
{
if (_meeting.Content == value)
return;
_meeting.Content = value;
this.RaisePropertyChanged("Content");
}
}
}
public class DocumentViewModel : ViewModelBase
{
private Document _document;
private RelayCommand _deleteDocumentCommand;
private RelayCommand _addDocumentCommand;
private RelayCommand _openDocumentCommand;
public DocumentViewModel(Document document)
{
_document = document;
}
private void DeleteDocument()
{
throw new NotImplementedException();
}
private bool CanDeleteDocument()
{
return _isSelected;
}
private void AddDocument()
{
}
private void OpenDocument()
{
}
public RelayCommand DeleteDocumentCommand
{
get { return _deleteDocumentCommand ?? (_deleteDocumentCommand = new RelayCommand(() => DeleteDocument(), () => CanDeleteDocument())); }
}
public RelayCommand AddDocumentCommand
{
get { return _addDocumentCommand ?? (_addDocumentCommand = new RelayCommand(() => AddDocument())); }
}
public RelayCommand OpenDocumentCommand
{
get { return _openDocumentCommand ?? (_openDocumentCommand = new RelayCommand(() => OpenDocument())); }
}
private bool _isSelected;
public bool IsSelected
{
get { return _isSelected; }
set
{
if (_isSelected == value)
return;
_isSelected = value;
this.RaisePropertyChanged("IsSelected");
}
}
public string Name
{
get { return _document.DocumentName; }
set
{
if (_document.DocumentName == value)
return;
_document.DocumentName = value;
this.RaisePropertyChanged("Name");
}
}
}
readonly Action<object> _execute;
readonly Predicate<object> _canExecute;
#endregion // Fields
#region Constructors
public RelayCommand(Action<object> execute)
: this(execute, null)
{
}
public RelayCommand(Action<object> execute, Predicate<object> canExecute)
{
if (execute == null)
throw new ArgumentNullException("execute");
_execute = execute;
_canExecute = canExecute;
}
#endregion // Constructors
#region ICommand Members
[DebuggerStepThrough]
public bool CanExecute(object parameter)
{
return _canExecute == null ? true : _canExecute(parameter);
}
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public void Execute(object parameter)
{
_execute(parameter);
}
#endregion // ICommand Members