3

我正在尝试使用 IDataErrorInfo 验证 MVVM 应用程序中的数据，但遇到了一些问题。

当我将 TextBox 设置为无效值时，验证工作正常。但是在我将 TextBox 的值设置为有效值之后，我得到了这个异常：

A first chance exception of type 'System.ArgumentOutOfRangeException' occurred in mscorlib.dll
A first chance exception of type 'System.Reflection.TargetInvocationException' occurred in mscorlib.dll
System.Windows.Data Error: 16 : Cannot get 'Item[]' value (type 'ValidationError') from '(Validation.Errors)' (type 'ReadOnlyObservableCollection`1'). BindingExpression:Path=(0).[0].ErrorContent; DataItem='TextBox' (Name='txtRunAfter'); target element is 'TextBox' (Name='txtRunAfter'); target property is 'ToolTip' (type 'Object') TargetInvocationException:'System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
    at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
    at System.ThrowHelper.ThrowArgumentOutOfRangeException()
    at System.Collections.Generic.List`1.get_Item(Int32 index)
    at System.Collections.ObjectModel.Collection`1.get_Item(Int32 index)
    at System.Collections.ObjectModel.ReadOnlyCollection`1.get_Item(Int32 index)
    --- End of inner exception stack trace ---
    at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
    at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
    at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
    at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
    at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)
    at MS.Internal.Data.PropertyPathWorker.GetValue(Object item, Int32 level)
    at MS.Internal.Data.PropertyPathWorker.RawValue(Int32 k)'

这是视图的代码：

    <UserControl x:Class="Telbit.TeStudio.View.Controls.TestStepListingStepView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Background="{Binding BackgroundColor}">

    <UserControl.Resources>
        <Style x:Key="TestStepTextBox" TargetType="{x:Type TextBox}">
            <Setter Property="Background" Value="Transparent" />
            <Setter Property="BorderThickness" Value="1"/>
            <Setter Property="BorderBrush" Value="Transparent"/>
            <Setter Property="VerticalContentAlignment" Value="Center"/>
            <Setter Property="HorizontalContentAlignment" Value="Left"/>
            <Setter Property="TextElement.FontSize" Value="10"/>
            <Setter Property="TextElement.FontWeight" Value="Regular"/>
            <Setter Property="Validation.ErrorTemplate" Value="{x:Null}"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type TextBox}">
                        <Border x:Name="Bd" SnapsToDevicePixels="true" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
                            <ScrollViewer x:Name="PART_ContentHost" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsMouseOver" Value="true">
                                <Setter Property="BorderBrush" Value="#3d62a9"/>
                            </Trigger>
                            <Trigger Property="IsFocused" Value="true">
                                <Setter Property="BorderBrush" Value="#3d62a9"/>
                                <Setter Property="Background" Value="White"/>
                            </Trigger>
                            <Trigger Property="Validation.HasError" Value="true">
                                <Setter Property="ToolTip"
                                    Value="{Binding RelativeSource={RelativeSource Self}, 
                                    Path=(Validation.Errors)[0].ErrorContent}"/>
                                <Setter Property="Background" Value="#33FF342D"/>
                                <Setter Property="BorderBrush" Value="#AAFF342D"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </UserControl.Resources>

    ...

    <TextBox Name="txtRunAfter" Grid.Column="4" Text="{Binding RunAfter, ValidatesOnDataErrors=True, NotifyOnValidationError=True, UpdateSourceTrigger=PropertyChanged}" Style="{StaticResource TestStepTextBox}"
         LostFocus="TextBoxLostFocus" PreviewKeyDown="TextBoxPreviewKeyDown" PreviewTextInput="TextBoxPreviewTextInput"/>

    ...

 </UserControl>

这是 ViewModel 的代码：

class TestStepListingStepViewModel : ViewModelBase, IDataErrorInfo
{
    private int _runAfter = 0;
    public int RunAfter
    {
        get
        {
            return _runAfter;
        }

        set
        {
            if (_runAfter != value)
            {
                _runAfter = value;
                OnPropertyChanged("RunAfter");
            }
        }
    }

string IDataErrorInfo.Error
    {
        get { return null; }
    }

    string IDataErrorInfo.this[string columnName]
    {
        get
        {
            string message = null;
            if (columnName == "RunAfter")
                message = validateRunAfter();

            return message;
        }
    }

    private string validateRunAfter()
    {
        if (_runAfter >= _order)
            return "Run After value must be less than its Step Order (#) value.";

        return null;
    }
}

这两天想弄清楚这是怎么回事！有一双新鲜眼睛的人能猜出来吗？

编辑：这是 TextBoxs 处理程序的代码：

public partial class TestStepListingStepView : UserControl
{
    private string mInvalidCharPattern = "[^0-9]";

    public TestStepListingStepView()
    {
        InitializeComponent();

        DataObject.AddPastingHandler(this.txtRunAfter, new DataObjectPastingEventHandler(TextBoxPasting));
    }

    private void TextBoxLostFocus(object sender, RoutedEventArgs e)
    {
        TextBox txt = sender as TextBox;

        if (txt != null && string.IsNullOrEmpty(txt.Text))
            txt.Text = "0";
    }

    // Catch the space character, since it doesn't trigger PreviewTextInput
    private void TextBoxPreviewKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Space) { e.Handled = true; }
    }

    // Do most validation here
    private void TextBoxPreviewTextInput(object sender, TextCompositionEventArgs e)
    {
        if (ValidateTextInput(e.Text) == false) { e.Handled = true; }
    }

    // Prevent pasting invalid characters
    private void TextBoxPasting(object sender, DataObjectPastingEventArgs e)
    {
        string lPastingText = e.DataObject.GetData(DataFormats.Text) as string;
        if (ValidateTextInput(lPastingText) == false) { e.CancelCommand(); }
    }

    // Do the validation in a separate function which can be reused
    private bool ValidateTextInput(string aTextInput)
    {
        if (aTextInput == null) { return false; }

        Match lInvalidMatch = Regex.Match(aTextInput, this.mInvalidCharPattern);
        return (lInvalidMatch.Success == false);
    }

}

另外，我使用的是 .Net Framework 3.5 版。我的应用程序非常复杂，因此我无法创建一个仅重新创建这部分的小项目。我希望你们中的一些人已经遇到过这个问题并且知道如何解决它。

再次感谢大家！

4

3 回答 3

7

Yep, Matt is right. I wish I looked his answer hour ago, not to spend time finding issue myself.

The other option that worked for me is to use converter class that checks if Errors list has items. So it will look like

<Trigger Property="Validation.HasError" Value="true"> 
<Setter Property="ToolTip" 
   Value="{Binding RelativeSource={RelativeSource Self}, Converter={StaticResource validationConverter},
   Path=(Validation.Errors)}"/> 

public class ValidationConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            ReadOnlyObservableCollection<ValidationError> errors = value as ReadOnlyObservableCollection<ValidationError>;
            if (errors == null) return value;
            if (errors.Count > 0)
            {
                return errors[0].ErrorContent;
            }
            return "";            
        }


        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException("This method should never be called");
        }
于 2010-06-22T19:46:32.993 回答
5

我相信问题出在 Validation.HasError 触发器中的 TextBox 模板。

<Trigger Property="Validation.HasError" Value="true">
    <Setter Property="ToolTip"
            Value="{Binding RelativeSource={RelativeSource Self}, 
            Path=(Validation.Errors)[0].ErrorContent}"/>
    <Setter Property="Background" Value="#33FF342D"/>
    <Setter Property="BorderBrush" Value="#AAFF342D"/>
</Trigger>

您正在引用验证错误的零项，当 Validation.HasError 为 True 时这很好。但是，当 Validation.HasError 设置为 False 时，您的 ToolTip 属性绑定将变为无效。

作为一种解决方法，您可以尝试在 Validation.HasError 上创建另一个触发器，其值为 False 以清除工具提示。

于 2010-06-22T17:42:48.787 回答
0

您正在引用验证错误的零项，当 Validation.HasError 为 True 时这很好。但是，当 Validation.HasError 设置为 False 时，您的 ToolTip 属性绑定将变为无效。

作为一种解决方法，您可以尝试在 Validation.HasError 上创建另一个触发器，其值为 False 以清除工具提示。

这个解决方案对我有用。感谢您的描述和帮助！

于 2015-06-23T12:45:58.243 回答