我正在开发一个带有 MainPage 的 WPF Web 应用程序，该应用程序使用 ninject 加载页面。
基本上，如果有一种方法可以告诉 NavigationService 由于用户更新了复合键中的值而导致 Id 发生了变化，我会感到很困惑。
我会尽力解释更多。我的 MultiTagPage 有一个 MultiTagViewModel，它显示了一个由 (MultiTagDef, Key, Value) 组成的多标签值。还有一个具有相同键和 MultiTagDef 的其他值的 DataGrid。如果您双击其中一个值，则会显示相应的多标签值。
在数据库中，多标签值与复合键（Multitagdef.Name、key、value）一起存储。因此，如果有人更新多标签值，则 ID 会更改（例如从 (A, B, C) 更改为 (A, B, D)）并保存，然后如果用户继续使用数据网格中的另一个多标签值 (A, B, E)并且可能会删除该对象，然后导航服务尝试加载（A，B，C）而不是（A，B，D）。
该体系结构是为具有 ID 列的对象设计的，该列当然永远不会改变。不幸的是，在这种情况下添加 ID 列不是一个选项。那么有人对如何解决这个问题提出建议吗？每次有人保存时我是否应该尝试重新加载页面，或者我可以告诉 NavigationService 当前对象现在已更改 ID？
现在，代码：
从主页：
public partial class MainPage : IUIService
{
public static readonly DependencyProperty MainModelProperty = PropertyHelper.Register<MainPage>(x => x.MainModel);
public MainModel MainModel
{
get { return (MainModel)GetValue(MainModelProperty); }
set { SetValue(MainModelProperty, value); }
}
private static readonly ILog log = LogManager.GetLogger(typeof(MainPage));
public MainPage()
{
// Make doubly sure...
ShowsNavigationUI = false;
InitializeComponent();
App.Kernel.Rebind<IUIService>().ToConstant(this);
MainModel = App.Kernel.Get<MainModel>();
WindowTitle = MainModel.Title;
ContentFrame.Navigating += Navigating;
ContentFrame.Navigated += Navigated;
ContentFrame.NavigationFailed += NavigationFailed;
}
private void Navigating(object sender, NavigatingCancelEventArgs args)
{
object dataContext = null;
if(ContentFrame.Content is FrameworkElement) {
dataContext = ((FrameworkElement)ContentFrame.Content).DataContext;
} else if(ContentFrame.Content is FrameworkContentElement) {
dataContext = ((FrameworkContentElement)ContentFrame.Content).DataContext;
}
if(dataContext is ISaveable && ((ISaveable)dataContext).NeedsSave) {
if(MessageControl.UnsavedSync() != MessageControl.Button.Yes) {
args.Cancel = true;
}
}
}
private void Navigated(object sender, NavigationEventArgs e)
{
var mi = e.ExtraData as MenuItemModel;
if(mi == null) {
var page = e.Content as IMenuItemPage;
if(page != null) {
mi = page.MenuItem;
}
if(mi == null) {
log.DebugFormat("Navigated to {0} ({1}) without menu item", e.Content, e.Uri);
return;
}
}
MainModel.CurrentMenuItem = mi;
if(mi.Type != MenuItemType.Folder) {
Settings.Default.AddRecentMenuItem(new RecentMenuItem(mi.MenuItem));
}
}
#region Generic Edit command
private void EditCanExecute(object sender, CanExecuteRoutedEventArgs e)
{
e.Handled = true;
e.CanExecute = false;
var param = Unwrap(e.Parameter);
var paramType = GetEditType(param);
if(paramType == null || !editPages.ContainsKey(paramType)) {
return;
}
e.CanExecute = ToConstructorArgument(param) != null;
}
private void EditExecuted(object sender, ExecutedRoutedEventArgs e)
{
Edit(e.Parameter);
}
private void Edit(object param)
{
var paramType = GetEditType(param);
if(paramType == null || !editPages.ContainsKey(paramType)) {
log.WarnFormat("Page for param {0} (type {1}) not found", param, paramType);
return;
}
if(param is IList) {
var list = (IList)param;
if(list.Count > 1000) {
Show("Too many items selected", "Please select no more than 1000 items at a time", messageTheme: MessageTheme.Warning);
return;
}
}
var arg = ToConstructorArgument(param);
if(arg == null) {
log.Warn("Unexpected parameter " + param + " supplied to EditExecuted");
return;
}
var pageType = editPages[paramType];
try {
log.DebugFormat("Got a parameter of type {0}, navigating to edit page {1}", param.GetType(), pageType);
Navigate(MakePage(pageType, arg));
} catch(Exception ex) {
log.Error("Unable to load edit page for parameter " + param, ex);
}
}
private static Page MakePage(Type pageType, params IParameter[] p)
{
var page = (Page)App.Kernel.Get(pageType, p);
var dp = ClientUtil.GetViewModelProperty(page.GetType());
if(dp != null) {
page.Loaded += (o, args) => {
var skrap = App.Kernel.Get(dp.PropertyType, p);
page.SetValue(dp, App.Kernel.Get(dp.PropertyType, p));
};
page.Unloaded += (o, args) => {
try {
page.ClearValue(dp);
} catch(Exception e) {
// Often happens when datagrid is in edit mode when navigating away from page:
// http://connect.microsoft.com/VisualStudio/feedback/details/571967/wpf-datagrid-causes-crash-with-sorting-is-not-allowed-during-an-addnew-or-edititem-transaction
log.Warn("Error while unloading page", e);
}
};
ViewModelBehavior.SetUpdateUIError(page, true);
}
return page;
}
#endregion
#region Navigate command
private void NavigateCanExecute(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = e.Parameter is Type;
e.Handled = true;
}
private void NavigateExecuted(object sender, ExecutedRoutedEventArgs e)
{
var type = e.Parameter as Type;
if(type == null) {
return;
}
Navigate(MakePage(type));
e.Handled = true;
}
#endregion
#region IUIService implementation
public void Navigate(Type type, params Tuple<string, object>[] parameters)
{
Navigate(MakePage(type, parameters.Select(x => new ConstructorArgument(x.Item1, x.Item2)).ToArray()));
}
public void Navigate(Type type, MenuItemModel menuItem, params Tuple<string, object>[] parameters)
{
Navigate(MakePage(type, parameters.Select(x => new ConstructorArgument(x.Item1, x.Item2))
.Prepend(new ConstructorArgument("menuItem", menuItem))
.Prepend(new ConstructorArgument("props", menuItem.Params))
.ToArray()),
menuItem);
}
public void Navigate(Page content, object extraData = null)
{
if(ContentFrame != null) {
if(ContentFrame.Content is DependencyObject) {
foreach(var dg in WpfUtil.FindDescendants<DataGrid>((DependencyObject)ContentFrame.Content)) {
while(!dg.CommitEdit()) { /* Keep committing */ }
}
}
ContentFrame.Navigate(content, extraData);
}
}
public bool NavigateBack()
{
if(ContentFrame != null && ContentFrame.CanGoBack) {
ContentFrame.GoBack();
return true;
}
if(NavigationService != null && NavigationService.CanGoBack) {
NavigationService.GoBack();
return true;
}
return false;
}
}
如果您需要更多信息，请告诉我。