WPF Binding.ValidationRules at Runtime

Question

I am in the process of writing validation rules for various controls in XAML. I would like to add validationRules to the controls at runtime, not in XAML. I was thinking about using converters. but any ideas / thoughts that would be the best way to accomplish this.

Code example:

<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(); } } 

Thanks,

Answer 1

The method I used is to create different styles in which my custom validation is embedded. Then it's just a matter of assigning the right style at runtime, which contains the necessary validation.

EDIT

The following is a basic example that creates a NumericTextBox style:

 <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> 

The following method is specified in the code file for the resource dictionary in which the style is stored. This method ensures that only numbers and a valid decimal separator can be entered in the text box. Each character is validated before it is actually displayed in the text box.

 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