运行时的WPF Binding.ValidationRules

2023年8月29日 332次阅读

我正在将验证规则写入XAML中的各种控件.我想在运行时而不是在XAML中将validationRules附加到控件.我在考虑使用转换器.但任何想法/想法,这将是更好的方式来实现这一目标.

示例代码：

 <TextBox Name="txtFirstName" >   <TextBox.Text>  <Binding Path="FirstName" ValidatesOnDataErrors="True" PropertyChanged" >
          <Binding.ValidationRules>
                <Binding Converter="{StaticResource validationConverter}"/>
           </Binding.ValidationRules>             
    </Binding>                                               


public class ValidationConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter,
        System.Globalization.CultureInfo culture)
    {
        Binding b = new Binding();
        b.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
        b.ValidatesOnDataErrors = true;
        b.NotifyOnValidationError = true;
        b.ValidationRules.Add(new RangeValidationRule { ErrorMessage = "Error shown from Converter ", MinValue = 10, MaxValue = 50 });
        return b;
    }

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

谢谢,

最佳答案 我使用的一种方法是创建不同的样式,并在其中内置自定义验证.然后,只需在运行时分配包含所需验证的正确Style.

编辑

下面是一个创建名为NumericTextBox的样式的基本示例：

<Style x:Key="NumericTextBox">
    <Setter Property="TextBox.VerticalAlignment"
            Value="Stretch"/>
    <Setter Property="TextBox.VerticalContentAlignment"
            Value="Center"/>
    <Setter Property="TextBox.Height"
            Value="24"/>
    <Setter Property="TextBox.Margin"
            Value="0,2,0,2"/>
    <EventSetter Event="UIElement.PreviewTextInput"
                 Handler="tbx_DigitCheck"/>
    <EventSetter Event="UIElement.PreviewKeyDown"
                 Handler="tbx_OtherCharCheck"/>
    <EventSetter Event="UIElement.PreviewDragEnter"
                 Handler="tbx_PreviewDragEnter"/>

</Style>

以下方法放在代码隐藏文件中,用于存储Style的资源字典.此方法确保只能在文本框中输入数字和有效的小数分隔符.在实际显示在文本框中之前,将检查每个字符的真实性.

Public Sub tbx_DigitCheck(ByVal sender As Object, _
                       ByVal e As TextCompositionEventArgs)

  //Retireve the sender as a textbox.
  Dim tbx As TextBox = CType(sender, TextBox)
  Dim val As Short

  //Get the current decimal separator.
  Dim dSep As String = Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator

  //Check to make sure that a decimal separator character has not
  //already been entered in the textbox.  Only make this check
  //for areas of the text that are not selected.
  If e.Text = dSep And tbx.SelectedText.Contains(dSep) Then
     //Do Nothing.  Allow the character to be typed.
  ElseIf e.Text = dSep And tbx.Text.Contains(dSep) Then
     e.Handled = True
  End If

  //Only allow the decimal separator and numeric digits.
  If Not Int16.TryParse(e.Text, val) And Not e.Text = dSep Then
     e.Handled = True
  End If

End Sub
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