Data binding 程序在使用可观察集合WP7导航时爆炸
在缅因州,在我的按钮上单击事件处理程序我执行:Data binding 程序在使用可观察集合WP7导航时爆炸,data-binding,collections,observable,Data Binding,Collections,Observable,在缅因州,在我的按钮上单击事件处理程序我执行: private void addIconButton_Click(object sender, EventArgs e) { if (test) { MessageBox.Show("enters addIcon Main"); Note note = new Note(); note.Modified = DateTimeOff
private void addIconButton_Click(object sender, EventArgs e)
{
if (test)
{
MessageBox.Show("enters addIcon Main");
Note note = new Note();
note.Modified = DateTimeOffset.Now;
if (note != null)
{
Settings.NotesList.Add(note); //this causes the issue.
//Settings.NotesList[0] = note;
}
Settings.CurrentNoteIndex = 0;
test = false;
MessageBox.Show("right before navigate");
this.NavigationService.Navigate(new Uri("/DetailsPage.XAML", UriKind.Relative));
MessageBox.Show("after navigate");
}
//DetailsPage mynewPage = new DetailsPage();
//this.Content = mynewPage;
}
在我的导航上,我做:
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
MessageBox.Show("enters onNav Main");
DataContext = null;
DataContext = Settings.NotesList;
Settings.CurrentNoteIndex = -1;
Listbox.SelectedIndex = -1;
if (Settings.NotesList != null)
{
if (Settings.NotesList.Count == 0)
{
Notes.Text = "No Notes";
}
else
{
Notes.Text = "";
}
}
}
在前端代码中,我执行以下操作:
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<ListBox x:Name="Listbox" SelectionChanged="listbox_SelectionChanged" ItemsSource="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<Border Width="800" MinHeight="60">
<StackPanel>
<TextBlock x:Name="Title" VerticalAlignment="Center" FontSize="{Binding TextSize}" Text="{Binding Name}"/>
<TextBlock x:Name="Date" VerticalAlignment="Center" FontSize="{Binding TextSize}" Text="{Binding Modified,
Mode=TwoWay, Converter={StaticResource dateConverter}}"/>
</StackPanel>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Grid>
当我单击应用程序按钮并在调用navigationService后立即调用invent处理程序时,我得到:
// Code to execute on Unhandled Exceptions
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
if (System.Diagnostics.Debugger.IsAttached)
{
// An unhandled exception has occurred; break into the debugger
System.Diagnostics.Debugger.Break();
}
}
仅当Settings.NotesList.Add(note)时才会发生这种情况;添加到addIconButton\u单击方法中
有什么建议吗 我通过在构造函数内的Notes类中为实例变量设置默认值来修复它
public class Note
{
public DateTimeOffset Modified { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public int TextSize { get; set; }
}
// Code to execute on Unhandled Exceptions
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
if (System.Diagnostics.Debugger.IsAttached)
{
// An unhandled exception has occurred; break into the debugger
System.Diagnostics.Debugger.Break();
}
}