Question

我有一个包含对象数组的数据网格，一切正常，直到我向错误集合添加错误（IErrorInfo）

Property Changged发生以下错误

protected virtual void SendPropertyChanged(String propertyName)
        {
            if ((this.PropertyChanged != null))
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); <//---- here
            }
        }

和DataGrid.UpdateLayout

    TimesheetArray = CreateMatrix(SelectedTimesheet.TimesheetDetails);
    RaisePropertyChanged("TimesheetArray");
    this.CrossTabDG.UpdateLayout();//----- HERE
    this.CrossTabDG.ItemsSource = this.TimesheetArray;

错误代码

System.ArgumentNullException occurred
  Message=Key cannot be null.
Parameter name: key
  Source=System
  ParamName=key
  StackTrace:
       at System.Collections.Specialized.HybridDictionary.get_Item(Object key)
       at System.ComponentModel.PropertyChangedEventManager.PrivateAddListener(INotifyPropertyChanged source, IWeakEventListener listener, String propertyName)
       at System.ComponentModel.PropertyChangedEventManager.AddListener(INotifyPropertyChanged source, IWeakEventListener listener, String propertyName)
       at MS.Internal.Data.PropertyPathWorker.ReplaceItem(Int32 k, Object newO, Object parent)
       at MS.Internal.Data.PropertyPathWorker.UpdateSourceValueState(Int32 k, ICollectionView collectionView, Object newValue, Boolean isASubPropertyChange)
       at MS.Internal.Data.ClrBindingWorker.AttachDataItem()
       at System.Windows.Data.BindingExpression.Activate(Object item)
       at System.Windows.Data.BindingExpression.AttachToContext(AttachAttempt attempt)
       at System.Windows.Data.BindingExpression.AttachOverride(DependencyObject target, DependencyProperty dp)
       at System.Windows.Data.BindingExpressionBase.Attach(DependencyObject target, DependencyProperty dp)
       at System.Windows.Data.BindingExpressionBase.OnAttach(DependencyObject d, DependencyProperty dp)
       at System.Windows.StyleHelper.GetInstanceValue(UncommonField`1 dataField, DependencyObject container, FrameworkElement feChild, FrameworkContentElement fceChild, Int32 childIndex, DependencyProperty dp, Int32 i, EffectiveValueEntry& entry)
       at System.Windows.StyleHelper.GetChildValueHelper(UncommonField`1 dataField, ItemStructList`1& valueLookupList, DependencyProperty dp, DependencyObject container, FrameworkObject child, Int32 childIndex, Boolean styleLookup, EffectiveValueEntry& entry, ValueLookupType& sourceType, FrameworkElementFactory templateRoot)
       at System.Windows.StyleHelper.GetChildValue(UncommonField`1 dataField, DependencyObject container, Int32 childIndex, FrameworkObject child, DependencyProperty dp, FrugalStructList`1& childRecordFromChildIndex, EffectiveValueEntry& entry, ValueLookupType& sourceType, FrameworkElementFactory templateRoot)
       at System.Windows.StyleHelper.GetValueFromStyleOrTemplate(FrameworkObject fo, DependencyProperty dp, EffectiveValueEntry& entry)
       at System.Windows.FrameworkElement.GetRawValue(DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry& entry)
       at System.Windows.FrameworkElement.EvaluateBaseValueCore(DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry& newEntry)
       at System.Windows.DependencyObject.EvaluateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry newEntry, OperationType operationType)
       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)
       at System.Windows.StyleHelper.InvalidateDependents(Style ownerStyle, FrameworkTemplate frameworkTemplate, DependencyObject container, DependencyProperty dp, FrugalStructList`1& dependents, Boolean invalidateOnlyContainer)
       at System.Windows.StyleHelper.OnTriggerSourcePropertyInvalidated(Style ownerStyle, FrameworkTemplate frameworkTemplate, DependencyObject container, DependencyProperty dp, DependencyPropertyChangedEventArgs changedArgs, Boolean invalidateOnlyContainer, FrugalStructList`1& triggerSourceRecordFromChildIndex, FrugalMap& propertyTriggersWithActions, Int32 sourceChildIndex)
       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.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
       at System.Windows.DependencyObject.SetValue(DependencyPropertyKey key, Object value)
       at System.Windows.Controls.Validation.AddValidationError(ValidationError validationError, DependencyObject targetElement, Boolean shouldRaiseEvent)
       at System.Windows.Data.BindingGroup.AddValidationError(ValidationError validationError)
       at System.Windows.Data.BindingGroup.ValidateOnDataTransfer()
       at System.Windows.Data.BindingGroup.OnLayoutUpdated(Object sender, EventArgs e)
       at System.Windows.ContextLayoutManager.fireLayoutUpdateEvent()
       at System.Windows.ContextLayoutManager.UpdateLayout()
       at System.Windows.UIElement.UpdateLayout()
       at TimesheetEntry.Views.TimesheetEntryViewModel.UpdateTimesheetGrid() in C:\Data Drive\Projects\DotNET\Laing_ORourke\source\TimesheetEntry\TimesheetEntry\Views\TimesheetEntry\TimesheetEntryViewModel.cs:line 405
  InnerException:

任何人都可以告诉我如何找到缺少的钥匙

1）PropertyName不为null 2）UpdateLayout（）不需要参数

没有验证错误 - 没有问题 - 但我需要它，

Answer 1

这通常在您为绑定所有者类型限定时发生，并且您指定的类型不是它在运行时绑定的类型。

例如：

<Setter Property="Canvas.Top" Value="{Binding (viewModels:FaceWithCandidates.Face).FaceRectangle.Top}" />

如果您正在验证绑定说您正在处理FaceWithCandidates并且在运行时，数据上下文包含任何其他类型，它将抛出此类异常。

在您的资产符合资格后检查您的Bindings！：）

Answer 2

我认为你已经解决了这个问题或继续前进，但我会发布这个以供将来参考。

使用带有我在TextBlock中显示的交替计数设置的ItemsControl时出现了同样的错误。它只发生在一台特定的机器上，但当我从ItemContainerStyle中删除下面的行时，异常消失了。

<TextBlock Text="{Binding (ItemsControl.AlternationIndex),
                          RelativeSource={RelativeSource Mode=TemplatedParent},
                          StringFormat='{}Item {0}'}"/>

因此，由于某些错误的XAML代码，似乎会发生此错误。您可以尝试删除controltemplate样式并查看是否有效，如果有，则添加元素直到再次出现错误，以便找出哪个元素不正确。似乎附属物是罪魁祸首，所以我会首先寻找那些。

验证时的关键空值错误

2 个答案: