ValidationRule.ValidatesOnTargetUpdated Property
[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]
Gets or sets a value that indicates whether the validation rule runs when the target of the Binding is updated.
Namespace: System.Windows.Controls
Assembly: PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
<object ValidatesOnTargetUpdated="bool" .../>
Property Value
Type: System.Booleantrue if the validation rule runs when the target of the Binding is updated; otherwise, false.
The following example checks whether the TextBox is empty. The ValidationRule, ValueIsNotNull, has ValidatesOnTargetUpdated set to true, so that when the application starts, the ValidationRule runs and displays a message if the TextBox is empty.
<TextBox Width="150" Validation.Error="ItemError"> <TextBox.Text> <Binding Source="{StaticResource myObject}" Path="PropertyB" UpdateSourceTrigger="PropertyChanged" NotifyOnValidationError="True"> <Binding.ValidationRules> <src:ValueIsNotNull ValidatesOnTargetUpdated="True" /> </Binding.ValidationRules> </Binding> </TextBox.Text> </TextBox>
The following example shows the ValidationRule that is used in the previous example and the event handler for the Error event.
public class ValueIsNotNull : ValidationRule { public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo) { string str = value as string; if (!string.IsNullOrEmpty(str)) { return ValidationResult.ValidResult; } else { return new ValidationResult(false, "Value must not be null"); } } }
Windows 8 Consumer Preview, Windows Server 8 Beta, Windows 7, Windows Server 2008 SP2, Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
