我正在使用此技术在视图之间导航:https://social.technet.microsoft.com/wiki/contents/articles/30898.simple-navigation-technique-in-wpf-using-mvvm.aspx
我有主ViewModel,菜单按钮绑定到SelectedViewModel属性更改命令:
class MainViewModel : INotifyPropertyChanged
{
public ICommand SomeViewCommand { get; set; }
public ICommand OtherViewCommand { get; set; }
private object selectedViewModel;
public event PropertyChangedEventHandler PropertyChanged;
public object SelectedViewModel
{
get { return selectedViewModel; }
set { selectedViewModel = value; OnPropertyChanged("SelectedViewModel"); }
}
public MainViewModel()
{
SomeViewCommand = new RelayCommand<object, object>(null, (object o) => OpenSomeView());
OtherViewCommand = new RelayCommand<object, object>(null, (object o) => OpenOtherView());
}
private void OpenSomeView()
{
SelectedViewModel = new SomeViewModel();
}
private void OpenOtherView(object obj)
{
if(SelectedViewModel != null && SelectedViewModel.GetType() == typeof(SomeViewModel))
{
SomeViewModel s = (SomeViewModel)SelectedViewModel;
// always 0
if (s.NumberOfChanges > 0)
{
MessageBox.Show("test", "Error");
}
// SelectedViewModel = new OtherViewModel(); after confirmation dialog
}
else
SelectedViewModel = new OtherViewModel();
}
private void OnPropertyChanged(string propName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
}
}
如果我在SomeView中,我想在切换到OtherView之前检查其属性(更改次数),并向用户显示确认对话框以确认其操作。我需要当前值,但任何属性似乎都有其初始化值。为什么呢?
这样做最干净的方法是什么?我知道可以通过使属性静态来完成,但这对我来说似乎很脏。
答案 0 :(得分:0)
在OnPropertyChanged方法中,您可以设置NumberOfChanges。