我允许用户通过视图中的 ContextMenu 菜单项删除项目，并且我希望在视图中自动看到效果。到目前为止，视图中的项目会一直保留到应用程序重新启动，在这种情况下它不再可见。这对于认为该项目已从应用程序中完全删除的用户来说是非常混乱的。我的问题是，我做错了什么可以解决这个问题？
应用程序.xaml.cs
//PictureRepository is a class that gathers pictures from IsolatedStorage
public static PictureRepository PictureList
{
get
{
return PictureRepository.Instance;
}
}
图片库.cs
#region Constants
public const string IsolatedStoragePath = "Pictures";
#endregion
#region Fields
private readonly ObservableCollection<Picture> _pictures = new ObservableCollection<Picture>();
#endregion
#region Properties
public ObservableCollection<Picture> Pictures
{
get { return _pictures; }
}
#endregion
#region Singleton Pattern
private PictureRepository()
{
LoadAllPicturesFromIsolatedStorage();
}
public static readonly PictureRepository Instance = new PictureRepository();
#endregion
/// <summary>
/// Saves to local storage
/// This method gets two parameters: the captured picture instance and the name of the pictures folder in the isolated storage
/// </summary>
/// <param name="capturedPicture"></param>
/// <param name="directory"></param>
public void SaveToLocalStorage(CapturedPicture capturedPicture, string directory)
{
//call IsolatedStorageFile.GetUserStoreForApplication to get an isolated storage file
var isoFile = IsolatedStorageFile.GetUserStoreForApplication();
//Call the IsolatedStorageFile.EnsureDirectory extension method located in the Common IsolatedStorageFileExtensions class to confirm that the pictures folder exists.
isoFile.EnsureDirectory(directory);
//Combine the pictures folder and captured picture file name and use this path to create a new file
string filePath = Path.Combine(directory, capturedPicture.FileName);
using (var fileStream = isoFile.CreateFile(filePath))
{
using (var writer = new BinaryWriter(fileStream))
{
capturedPicture.Serialize(writer);
}
}
}
/// <summary>
/// To load all saved pictures and add them to the pictures list page
/// </summary>
public CapturedPicture LoadFromLocalStorage(string fileName, string directory)
{
//To open the file, add a call to the IsolatedStorageFile.GetUserStoreForApplication
var isoFile = IsolatedStorageFile.GetUserStoreForApplication();
//Combine the directory and file name
string filePath = Path.Combine(directory, fileName);
//use the path to open the picture file from the isolated storage by using the IsolatedStorageFile.OpenFile method
using (var fileStream = isoFile.OpenFile(filePath, FileMode.Open, FileAccess.Read))
{
//create a BinaryReader instance for deserializing the CapturedPicture instance
using (var reader = new BinaryReader(fileStream))
{
var capturedPicture = new CapturedPicture();
//create a new instance of the type CapturedPicture called CapturedPicture.Deserialize to deserialize the captured picture and return it
capturedPicture.Deserialize(reader);
return capturedPicture;
}
}
}
/// <summary>
/// To load all the pictures at start time
/// </summary>
private void LoadAllPicturesFromIsolatedStorage()
{
//add call to the IsolatedStorageFile.GetUserStoreForApplication to open an isolated storage file
var isoFile = IsolatedStorageFile.GetUserStoreForApplication();
//Call the IsolatedStorageFile.EnsureDirectory extension method located in the Common IsolatedStorageFileExtensions class to confirm that the pictures folder exists
isoFile.EnsureDirectory(IsolatedStoragePath);
//Call the IsolatedStorageFile.GetFileNames using the pictures directory and *.jpg as a filter to get all saved pictures
var pictureFiles = isoFile.GetFileNames(Path.Combine(IsolatedStoragePath, "*.jpg"));
//var pictureFiles = isoFile.GetFileNames(Path.Combine(IsolatedStoragePath, ""));
//Iterate through all the picture files in the list and load each using the LoadFromLocalStorage you created earlier
foreach (var pictureFile in pictureFiles)
{
var picture = LoadFromLocalStorage(pictureFile, IsolatedStoragePath);
_pictures.Add(picture);
}
}
MainPage.xaml.cs
protected override void OnNavigatedTo(NavigationEventArgs e)
{
//Recent is the ListBox in the view that is populated from the ObservableCollection
if (Settings.AscendingSort.Value)
{
//Recent.ItemsSource = PictureRepository.Instance.Pictures.OrderBy(x => x.DateTaken);
Recent.ItemsSource = App.PictureList.Pictures.OrderBy(x => x.DateTaken);
}
else
{
//Recent.ItemsSource = PictureRepository.Instance.Pictures.OrderByDescending(x => x.DateTaken);
Recent.ItemsSource = App.PictureList.Pictures.OrderByDescending(x => x.DateTaken);
}
}
//My attempt at deleting the item from both the View and IsolatedStorage
private void deleteContextMenuItem_Click(object sender, RoutedEventArgs e)
{
var listBoxItem = ((MenuItem)sender).DataContext as CapturedPicture;
fileName = listBoxItem.FileName;
if (fileName != null)
{
try
{
//Neither of the following remove the item from the View immediately
App.PictureList.Pictures.Remove(listBoxItem);
PictureRepository.Instance.Pictures.Remove(listBoxItem);
//To open the file, add a call to the IsolatedStorageFile.GetUserStoreForApplication
var isoFile = IsolatedStorageFile.GetUserStoreForApplication();
//Combine the directory and file name
string filePath = Path.Combine(PictureRepository.IsolatedStoragePath, fileName);
isoFile.DeleteFile(filePath);
}
catch
{
MessageBoxResult r = MessageBox.Show("There was an error deleting the image.", "Notice", MessageBoxButton.OK);
if (r == MessageBoxResult.OK)
return;
}
}
}
如您所见，我正在尝试从视图和独立存储中删除该项目。截至目前，从 IsolatedStorage 中的删除工作正常，但我似乎无法让视图自动更新？我必须等到应用程序重新启动并且在OnNavigatedTo事件中重新填充 ListBox 才能看到任何更改。