Question

我有一个非常简单的DataGrid绑定到自定义对象的集合。自定义对象使用DataAnnotations注释并实现IDataErrorInfo。

public class MyObject : IDataErrorInfo {
    [Required(ErrorMessageResourceName = "Amount_Required", ErrorMessageResourceType = typeof(Resources))]
    [Range(typeof(decimal), "0", "1000000000", ErrorMessageResourceName = "InventoryCost_Amount_Invalid", ErrorMessageResourceType = typeof(Resources))]
    public decimal? Amount { get; set; }

    [Required(ErrorMessageResourceName = "Name_Required", ErrorMessageResourceType = typeof(Resources))]
    [StringLength(50, ErrorMessageResourceName = "Name_MaxLength", ErrorMessageResourceType = typeof(Resources))]
    public string Name { get; set; }

    // standard IDataErrorInfo stuff here
 }

我希望DataGrid验证其中的任何对象，并且我将能够在代码中检测对象是否正确。我尝试了以下方式：

在UserControl

中添加所有验证错误的集合

private readonly List<Tuple<object, ValidationError>> errors = new List<Tuple<object, ValidationError>>();

在UserControl的构造函数中添加验证处理程序：
```
Validation.AddErrorHandler(this, ErrorChangedHandler);
```

处理验证已更改：

private void ErrorChangedHandler(object sender, ValidationErrorEventArgs e)
{
    Debug.WriteLine(e.Action.ToString() + ":object=" + e.OriginalSource.ToString() + ",error=" + e.Error.ToString());
    if (e.Action == ValidationErrorEventAction.Added)
    {
        errors.Add(new Tuple<object, ValidationError>(e.OriginalSource, e.Error));
    }
    else
    {
        Tuple<object, ValidationError> error = errors.FirstOrDefault(err => err.Item1 == e.OriginalSource && err.Item2 == e.Error);
        if (error != null) { errors.Remove(error); }
    }
    bool hasError = !errors.Any();
}

如果我编辑现有对象，这是正确的，但如果我尝试添加新对象，则错误更改事件流非常奇怪：TextBlock的验证错误会添加到即使我为所有两个字段添加了正确的值，也会创建并永远不会删除新对象。这是我的日志（我记录了所有验证错误）：

(I created new row,i.e. object)

添加了：对象= System.Windows.Controls.TextBlock，误差= System.Windows.Controls.ValidationError 添加了：对象= System.Windows.Controls.TextBlock，误差= System.Windows.Controls.ValidationError 添加了：对象= System.Windows.Controls.TextBox，误差= System.Windows.Controls.ValidationError 添加了：对象= System.Windows.Controls.DataGridCell，误差= System.Windows.Controls.ValidationError 删除：对象= System.Windows.Controls.DataGridCell，误差= System.Windows.Controls.ValidationError

(I put correct value for Name field)

移除：对象= System.Windows.Controls.TextBox，误差= System.Windows.Controls.ValidationError 添加了：对象= System.Windows.Controls.TextBox，误差= System.Windows.Controls.ValidationError 添加了：对象= System.Windows.Controls.DataGridCell，误差= System.Windows.Controls.ValidationError

(I put correct value for Amount field, now object (and whole row is the grid) is valid)

移除：对象= System.Windows.Controls.DataGridCell，误差= System.Windows.Controls.ValidationError 删除：对象= System.Windows.Controls.TextBox，误差= System.Windows.Controls.ValidationError

但是没有删除与TextBlock相关的前两个错误，因此所有错误的列表都不为空，并且ErrorChangedHandler中的hasError变量为false。我的XAML也很简单：

    <DataGrid x:Name="grid"
              ItemsSource="{Binding MyObjects}" 
              CanUserDeleteRows="False" Margin="11,11,11,11" 
              AutoGenerateColumns="False"
              Height="308">
        <DataGrid.Columns>
            <DataGridTextColumn Binding="{Binding Path=Name, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, 
                                ValidatesOnExceptions=True, NotifyOnValidationError=True}" 
                                Header="Name" Width="100" ElementStyle="{StaticResource TextCellElementStyle}"
                                EditingElementStyle="{StaticResource TextCellEditingStyle}"/>
            <DataGridTextColumn Binding="{Binding Path=Amount, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, 
                                ValidatesOnExceptions=True, NotifyOnValidationError=True}" 
                                Header="Amount" Width="75" ElementStyle="{StaticResource TextCellElementStyle}"
                                EditingElementStyle="{StaticResource TextCellEditingStyle}"/>
        </DataGrid.Columns>
    </DataGrid>

在WPF DataGrid中的TextBlock上未调用Validation.ErrorChangedHandler

0 个答案: