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Binding.ValidatesOnDataErrors Property

Gets or sets a value that indicates whether to include the DataErrorValidationRule.

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

member ValidatesOnDataErrors : bool with get, set
<object ValidatesOnDataErrors="bool" .../>

Property Value

Type: System.Boolean
true to include the DataErrorValidationRule; otherwise, false.

Setting this property provides an alternative to using the DataErrorValidationRule element explicitly. The DataErrorValidationRule is a built-in validation rule that checks for errors that are raised by the IDataErrorInfo implementation of the source object. If an error is raised, the binding engine creates a ValidationError with the error 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.

ValidatesOnDataErrors is introduced in the .NET Framework version 3.5. For more information, see .NET Framework Versions and Dependencies.

The following examples uses IDataErrorInfo and ValidatesOnDataErrors to validate user input in a TextBox. The first example creates a data type that implements IDataErrorInfo to report validation errors.

No code example is currently available or this language may not be supported.

The following example binds the Age property to the TextBox and sets ValidatesOnDataErrors 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 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>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5 SP1, 3.0 SP1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), 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.

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