我有一个 ViewModelMain 我正在更改我当前的视图和当前的 ViewModels。
public ViewModelBase CurrentVm { get; set; }
public UserControl Content
{
get { return _content; }
set
{
_content = value;
RaisePropertyChanged(() => Content); // this is the Line where i get the Exception
}
}
当我从一个带有 LocBinding 的特定视图导航到另一个没有 LocBinding 的视图时，就会出现问题。
在当前视图中，我有一个带有组合框的 locBinding
<ComboBox MinWidth="45" MaxWidth="80" Grid.Column="1" ItemsSource="{Binding AmountUnits.View}" ItemTemplate="{StaticResource NameResourceKeyTextBoxItemTemplate}" />
物品模板：
<DataTemplate x:Key="NameResourceKeyTextBoxItemTemplate" >
<StackPanel>
<StackPanel.Resources>
<lex:LocExtension x:Key="LocalizedHeader" x:Name="LocalizedHeader"/>
</StackPanel.Resources>
<Engine:LocBinding Source="{Binding Name, Mode=OneWay}" Target="{x:Reference LocalizedHeader}" />
<TextBlock Text="{x:Reference LocalizedHeader}" />
</StackPanel>
</DataTemplate>
绑定的属性（在我的 ViewModel 中）：
private CollectionViewSource _amountUnits;
public CollectionViewSource AmountUnits
{
get { return _amountUnits; }
set { _amountUnits = value;
RaisePropertyChanged(() => AmountUnits);
}
}
AmountUnits.Source =
AmountUnit.GetAll().Select(x => new MaterialInputProp(x.Id, x.TransKey)
{
Name = x.TransKey,
IsSelected = x.IsSelected
}).ToList();
这一切都很好......虽然当我在我的ViewModelMain中更改我的视图并且我的当前视图的PropertyChanged被提升时，我得到一个NullReferenceException..：/它不在乎我的新ViewModel是空的还是复杂的......当我我正在更改我的用户控制内容我得到了异常..：/
例如。我如何在我的 ViewModelMain 中更改我的视图
CurrentVm = new MaterialInputViewModel(mc.NewValue);
Content = new InputView();
在内容设置器中它打破了......
堆栈跟踪：
at WPFLocalizeExtension.Engine.LocBinding.OnPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp, Boolean preserveCurrentValue)
at System.Windows.Data.BindingExpressionBase.Invalidate(Boolean isASubPropertyChange)
at System.Windows.Data.BindingExpression.TransferValue(Object newValue, Boolean isASubPropertyChange)
at System.Windows.Data.BindingExpression.Activate(Object item)
at System.Windows.Data.BindingExpression.OnDataContextChanged(DependencyObject contextElement)
at System.Windows.Data.BindingExpression.HandlePropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args)
at System.Windows.Data.BindingExpressionBase.OnPropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args)
at System.Windows.Data.BindingExpression.OnPropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args)
at System.Windows.DependentList.InvalidateDependents(DependencyObject source, DependencyPropertyChangedEventArgs sourceArgs)
at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
...
如果您需要更多信息，请询问...我需要帮助！这很紧急... ：/