RelayCommand 中的对象发送者始终为空
我正在使用 RelayCommand 来处理按钮单击，我需要获取发送者参数，但它始终为空，知道为什么吗？
ViewModel.cs
private RelayCommand _expandClickCommand;
public ICommand ExpandClickCommand
{
get
{
if (_expandClickCommand == null)
{
_expandClickCommand = new RelayCommand(ExpandClickCommandExecute, ExpandClickCommandCanExecute);
}
return _expandClickCommand;
}
}
public void ExpandClickCommandExecute(object sender)
{
//sender is always null when i get here!
}
public bool ExpandClickCommandCanExecute(object sender)
{
return true;
}
View.xaml
<ListBox ItemsSource="{Binding Path=MyList}">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Button Grid.Column="0" Grid.Row="0" Content="Expand" Command="{Binding DataContext.ExpandClickCommand,ElementName=SprintBacklog}"/>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
我需要获取 ExpandClickCommand 中当前 ListboxItem 的索引
I am using RelayCommand to handle a button click, I need to get the sender parameter but it is always null, any idea why?
ViewModel.cs
private RelayCommand _expandClickCommand;
public ICommand ExpandClickCommand
{
get
{
if (_expandClickCommand == null)
{
_expandClickCommand = new RelayCommand(ExpandClickCommandExecute, ExpandClickCommandCanExecute);
}
return _expandClickCommand;
}
}
public void ExpandClickCommandExecute(object sender)
{
//sender is always null when i get here!
}
public bool ExpandClickCommandCanExecute(object sender)
{
return true;
}
View.xaml
<ListBox ItemsSource="{Binding Path=MyList}">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Button Grid.Column="0" Grid.Row="0" Content="Expand" Command="{Binding DataContext.ExpandClickCommand,ElementName=SprintBacklog}"/>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I need to get the index of the currect ListboxItem in ExpandClickCommand
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
该对象很可能不是发送者，而是由控件传递的
CommandParameter。您可以将按钮的CommandParameter绑定到其自身以模仿sender。（但这可能对您没有太大帮助，因此请考虑一下您传入的内容可以帮助您获得该值。）
That object in all likelihood is not the sender but the
CommandParameterthat is passed by the control. You could bind theCommandParameterof the button to itself to immitate thesender.(But that might not really help you that much, so think about what you pass in that helps you get that value.)