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DataErrorValidationRule Class

Represents a rule that checks for errors that are raised by the IDataErrorInfo implementation of the source object.

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

'Declaration
Public NotInheritable Class DataErrorValidationRule _
	Inherits ValidationRule
'Usage
Dim instance As DataErrorValidationRule
<DataErrorValidationRule .../>

The WPF data binding model enables you to associate ValidationRules with a Binding object. If your source object implements the IDataErrorInfo interface, you can use the built-in rule DataErrorValidationRule to check for errors raised by the IDataErrorInfo implementation.

An alternative syntax to setting the DataErrorValidationRule explicitly is to set the ValidatesOnDataErrors property to true on your Binding or MultiBinding object.

You can create a custom rule by creating a class that derives from ValidationRule. For more information and a detailed discussion of data validation, see Data Binding Overview.

DataErrorValidationRule is introduced in the .NET Framework version 3.5. For more information, see .NET Framework 3.5 Architecture.

This example shows how to implement validation logic on a custom object and then bind to it.

You can provide validation logic on the business layer if your source object implements IDataErrorInfo, as in the following example:

public class Person : 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;
        }
    }
}

In the following example, the text property of the text box binds to the Age property of the Person object, which has been made available for binding through a resource declaration that is given the x:Key data. The DataErrorValidationRule checks for the validation errors raised by the IDataErrorInfo implementation.

<TextBox Style="{StaticResource textBoxInError}">
  <TextBox.Text>
    <Binding Path="Age" Source="{StaticResource data}"
             UpdateSourceTrigger="PropertyChanged">
      <Binding.ValidationRules>
        <!--DataErrorValidationRule checks for validation 
            errors raised by the IDataErrorInfo object
            Alternatively, you can set ValidatesOnDataErrors="True"
            on the Binding.-->
        <DataErrorValidationRule/>
      </Binding.ValidationRules>
    </Binding>
  </TextBox.Text>
</TextBox>

Alternatively, instead of using the DataErrorValidationRule, you can set the ValidatesOnDataErrors property to true.

For the complete sample, see Business Layer Validation Sample.

System.Object
  System.Windows.Controls.ValidationRule
    System.Windows.Controls.DataErrorValidationRule

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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

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