Namespace:
System.Windows.Data
Assembly:
PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
Visual Basic (Declaration)
Public Property ValidatesOnExceptions As Boolean
Dim instance As Binding
Dim value As Boolean
value = instance.ValidatesOnExceptions
instance.ValidatesOnExceptions = value
public bool ValidatesOnExceptions { get; set; }
public:
property bool ValidatesOnExceptions {
bool get ();
void set (bool value);
}
public function get ValidatesOnExceptions () : boolean
public function set ValidatesOnExceptions (value : boolean)
<object ValidatesOnExceptions="bool" .../>
Setting this property provides an alternative to using the ExceptionValidationRule element explicitly. The ExceptionValidationRule is a built-in validation rule that checks for exceptions that are thrown during the update of the source property. If an exception is thrown, the binding engine creates a ValidationError with the exception and adds it to the Validation..::.Errors collection of the bound element. The lack of an error clears this validation feedback, unless another rule raises a validation issue.
ValidatesOnExceptions is introduced in the .NET Framework version 3.5. For more information, see .NET Framework 3.5 Architecture.
The following examples use ValidatesOnExceptions to validate user input in a TextBox. The first example creates a data type that throws an exception when the Age property is set to an invalid property.
Public Class PersonImplementsIDataErrorInfo
Implements System.ComponentModel.IDataErrorInfo
Private m_age As Integer
Public Property Age() As Integer
Get
Return m_age
End Get
Set(ByVal value As Integer)
m_age = value
End Set
End Property
Public ReadOnly Property [Error]() As String _
Implements System.ComponentModel.IDataErrorInfo.Error
Get
Return Nothing
End Get
End Property
Default Public ReadOnly Property Item(ByVal name As String) As String _
Implements System.ComponentModel.IDataErrorInfo.Item
Get
Dim result As String = Nothing
If name = "Age" Then
If Me.m_age < 0 OrElse Me.m_age > 150 Then
result = "Age must not be less than 0 or greater than 150."
End If
End If
Return result
End Get
End Property
End Class
public class PersonImplementsIDataErrorInfo : IDataErrorInfo
{
private int age;
public int Age
{
get { return age; }
set { age = value; }
}
public string Error
{
get
{
return null;
}
}
public string this[string name]
{
get
{
string result = null;
if (name == "Age")
{
if (this.age < 0 || this.age > 150)
{
result = "Age must not be less than 0 or greater than 150.";
}
}
return result;
}
}
}
The following example binds the Age property to the TextBox and sets ValidatesOnExceptions to true on the Binding. When the user enters an invalid value, a red border appears in the TextBox and the ToolTip reports the error message.
<StackPanel>
<StackPanel Margin="20">
<StackPanel.Resources>
<src:PersonImplementsIDataErrorInfo x:Key="data"/>
<!--The tool tip for the TextBox to display the validation error message.-->
<Style x:Key="textBoxInError" TargetType="TextBox">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip"
Value="{Binding RelativeSource={x:Static RelativeSource.Self},
Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
</Style>
</StackPanel.Resources>
<TextBlock>Enter your age:</TextBlock>
<TextBox Style="{StaticResource textBoxInError}">
<TextBox.Text>
<!--ValidatesOnDataErrors to is set to True, so the Binding
checks for errors raised by the IDataErrorInfo object.
An alternative syntax is to add <DataErrorValidationRule/> within
the <Binding.ValidationRules> section.-->
<Binding Path="Age" Source="{StaticResource data}"
ValidatesOnDataErrors="True"
UpdateSourceTrigger="PropertyChanged">
</Binding>
</TextBox.Text>
</TextBox>
<TextBlock>Mouse-over to see the validation error message.</TextBlock>
</StackPanel>
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5 SP1, 3.0 SP1
Reference
Other Resources