WPF DataGrid 验证错误未清除

Question

所以我有一个 WPF DataGrid ，绑定(bind)到 ObservableCollection .该集合通过 IDataErrorInfo 对其成员进行了验证.如果我以一种无效的方式编辑一个单元格，然后在按 Enter 之前将其移开，然后返回并使其有效，则该单元格将停止显示无效，但是，“!”行首仍然存在，ToolTip将引用先前的无效值。

Answer 1

最初的问题来自 2011 年，Datagrids Validation-System 仍然存在问题，无法使用。我花了 2 天时间试图找到一个解决方案来完成以下工作:

我的模型项实现 INotifyDataErrorInfo 和 INotifyPropertyChanged

它们位于绑定(bind)到 DataGrid

的 BindingList 中

DataGrid 应该显示来自用户输入的验证错误以及来自不同来源的模型更改

RowValidation-Error-mark 应该显示任何单元格是否有验证错误，否则隐藏，无论用户当前是否正在编辑、提交或对行不做任何事情

无效单元格应显示带有错误文本的工具提示

没有错误或故障

实现此行为的唯一方法是放弃 RowValidation 和 CellValidation，而使用 RowHeader 和 Styles。我从网络上的各种来源复制了以下代码。我还不能对此进行广泛的测试，但乍一看它看起来很有希望。
在 DataGrids XAML 中:

<DataGrid ... local:DataGridProps.ShowCellErrorBorder="False">
<DataGrid.Resources>
    <local:DataGridValidationConverter x:Key="DataGridValidationConverter" />
    <Style TargetType="TextBlock" x:Key="errTemplate">
        <Style.Triggers>
            <Trigger Property="Validation.HasError" Value="true">
                <Setter Property="ToolTip"
                      Value="{Binding Path=(Validation.Errors)[0].ErrorContent}
                        RelativeSource={x:Static RelativeSource.Self}, "/>
                <Setter Property="Background" Value="LightSalmon"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</DataGrid.Resources>

<DataGrid.RowValidationErrorTemplate>
    <ControlTemplate>
            
    </ControlTemplate>
</DataGrid.RowValidationErrorTemplate>

<DataGrid.RowHeaderTemplate>
    <DataTemplate>
        <Grid Margin="0,-2,0,-2" 
              Visibility="{Binding Path=DataContext.HasErrors,
                RelativeSource={RelativeSource Mode=FindAncestor,
                  AncestorType={x:Type DataGridRow}},
                Converter={StaticResource DataGridValidationConverter},
                FallbackValue=Hidden}">
            <Ellipse StrokeThickness="0" Fill="Red"
                    Width="{Binding Path=FontSize,
                      RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type DataGridRow}}}"
                    Height="{Binding Path=FontSize,
                      RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type DataGridRow}}}" />
            <TextBlock Text="!" FontWeight="Bold" Foreground="White" HorizontalAlignment="Center"
                    FontSize="{Binding Path=FontSize,
                      RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type DataGridRow}}}" />               
        </Grid>
    </DataTemplate>
</DataGrid.RowHeaderTemplate>

<DataGrid.Columns>
    <DataGridTextColumn Header="Vorname" ElementStyle="{StaticResource errTemplate}"
          Binding="{Binding Path=Vorname,
             ValidatesOnNotifyDataErrors=True,
             NotifyOnValidationError=True}" />
    ...
</DataGrid.Columns>
</DataGrid>

数据网格验证转换器:

public class DataGridValidationConverter : IValueConverter
{
       
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if ((bool)value)
            return Visibility.Visible;
        else
            return Visibility.Hidden;
    }

       
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

数据网格 Prop :

public class DataGridProps
{
public static readonly DependencyProperty ShowCellErrorBorderProperty = DependencyProperty.RegisterAttached(
            "ShowCellErrorBorder", typeof(bool), typeof(DataGridProps), new PropertyMetadata(true, ShowCellErrorBorderPropertyChangedCallback));

public static bool GetShowCellErrorBorder(DependencyObject element)
{
    return (bool)element.GetValue(ShowCellErrorBorderProperty);
}

public static void SetShowCellErrorBorder(DependencyObject element, bool value)
{
    element.SetValue(ShowCellErrorBorderProperty, value);
}

private static void ShowCellErrorBorderPropertyChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
    if (GetShowCellErrorBorder(dependencyObject)) return;
    var dg = dependencyObject as DataGrid;
    if (null != dg)
    {
        dg.Loaded += (sender, args) =>
        {
            var scrollView = dg.Template.FindName("DG_ScrollViewer", dg) as ScrollViewer;
            if (null == scrollView) return;
            var scrollContent = scrollView.Template.FindName("PART_ScrollContentPresenter", scrollView) as ScrollContentPresenter;
            if (null == scrollContent) return;
            scrollContent.AdornerLayer.Visibility = Visibility.Hidden;
        };
    }
}
}

模型的实现:

public Model()
{
    if (Vorname == null)
        Vorname = "";
    ...

    errorsByPropertyName = new Dictionary<string, List<string>>();
    this.PropertyChanged += Model_PropertyChanged;
    ForceRevalidation(null);
}

private string _vorname;
public string Vorname { get => _vorname; set => SetField(ref _vorname, value); }
...

public event PropertyChangedEventHandler PropertyChanged;

protected void OnPropertyChanged([CallerMemberName] string propertyName = null) =>
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

protected bool SetField<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
{
    if (EqualityComparer<T>.Default.Equals(field, value)) return false;
    field = value;
    OnPropertyChanged(propertyName);
    return true;
}

private Dictionary<string, List<string>> errorsByPropertyName;

public void ForceRevalidation(string propertyName)
{
    if (string.IsNullOrEmpty(propertyName))
    {
        foreach (PropertyInfo property in GetType().GetProperties())
        {
            ValidateProperty(property.Name);
        }
    }
    else
    {
        ValidateProperty(propertyName);
    }
}

protected virtual void OnErrorsChanged(string propertyName)
{
    ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(propertyName));
    OnPropertyChanged(nameof(HasErrors));
}

public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;

public bool HasErrors => errorsByPropertyName.Any();

public System.Collections.IEnumerable GetErrors(string propertyName)
{
    if (propertyName == null)
        propertyName = "";
    return errorsByPropertyName.ContainsKey(propertyName) ? errorsByPropertyName[propertyName] : null;
}

private void Model_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    ValidateProperty(e.PropertyName);
}

protected virtual void ValidateProperty(string propertyName)
{
    if (propertyName == null)
        propertyName = "";

    ClearErrors(propertyName);

    switch (propertyName)
    {
        case nameof(Vorname):
            if (string.IsNullOrWhiteSpace(Vorname))
                AddError(propertyName, propertyName + " is empty");
            break;
        ...
        default:
            break;

    }
}

protected void AddError(string propertyName, string error)
{
    if (!errorsByPropertyName.ContainsKey(propertyName))
        errorsByPropertyName[propertyName] = new List<string>();

    if (!errorsByPropertyName[propertyName].Contains(error))
    {
        errorsByPropertyName[propertyName].Add(error);
        OnErrorsChanged(propertyName);
    }
}

protected void ClearErrors(string propertyName)
{
    if (errorsByPropertyName.ContainsKey(propertyName))
    {
        errorsByPropertyName.Remove(propertyName);
        OnErrorsChanged(propertyName);
    }
}

我从我更大的 Model-Base-Class 中创建了这个最小的例子，希望我在这里得到了这方面的所有重要信息。