我在一个选项卡页面上的用户控件中绑定上下文菜单的命令时遇到了问题。
第一次使用菜单（右键单击标签页）时，它能够正常工作，但如果我切换选项卡，则该命令将使用第一次使用的数据绑定实例。
如果我在用户控件中放置一个绑定到该命令的按钮，则它会按预期工作...
请问有人能告诉我我做错了什么吗？？
这是一个显示问题的测试项目：
App.xaml.cs：
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
CompanyViewModel model = new CompanyViewModel();
Window1 window = new Window1();
window.DataContext = model;
window.Show();
}
}
Window1.xaml:
<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vw="clr-namespace:WpfApplication1"
Title="Window1" Height="300" Width="300">
<Window.Resources>
<DataTemplate x:Key="HeaderTemplate">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Path=Name}" />
</StackPanel>
</DataTemplate>
<DataTemplate DataType="{x:Type vw:PersonViewModel}">
<vw:UserControl1/>
</DataTemplate>
</Window.Resources>
<Grid>
<TabControl ItemsSource="{Binding Path=Persons}"
ItemTemplate="{StaticResource HeaderTemplate}"
IsSynchronizedWithCurrentItem="True" />
</Grid>
</Window>
UserControl1.xaml:
<UserControl x:Class="WpfApplication1.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
MinWidth="200">
<UserControl.ContextMenu>
<ContextMenu >
<MenuItem Header="Change" Command="{Binding Path=ChangeCommand}"/>
</ContextMenu>
</UserControl.ContextMenu>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Label Grid.Column="0">The name:</Label>
<TextBox Grid.Column="1" Text="{Binding Path=Name, UpdateSourceTrigger=PropertyChanged}" />
</Grid>
</UserControl>
CompanyViewModel.cs:
public class CompanyViewModel
{
public ObservableCollection<PersonViewModel> Persons { get; set; }
public CompanyViewModel()
{
Persons = new ObservableCollection<PersonViewModel>();
Persons.Add(new PersonViewModel(new Person { Name = "Kalle" }));
Persons.Add(new PersonViewModel(new Person { Name = "Nisse" }));
Persons.Add(new PersonViewModel(new Person { Name = "Jocke" }));
}
}
PersonViewModel.cs:
public class PersonViewModel : INotifyPropertyChanged
{
Person _person;
TestCommand _testCommand;
public PersonViewModel(Person person)
{
_person = person;
_testCommand = new TestCommand(this);
}
public ICommand ChangeCommand
{
get
{
return _testCommand;
}
}
public string Name
{
get
{
return _person.Name;
}
set
{
if (value == _person.Name)
return;
_person.Name = value;
OnPropertyChanged("Name");
}
}
void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(this, e);
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
TestCommand.cs:
public class TestCommand : ICommand
{
PersonViewModel _person;
public event EventHandler CanExecuteChanged;
public TestCommand(PersonViewModel person)
{
_person = person;
}
public bool CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
_person.Name = "Changed by command";
}
}
Person.cs:
public class Person
{
public string Name { get; set; }
}