DataErrorValidationRule Class
[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]
Represents a rule that checks for errors that are raised by the IDataErrorInfo implementation of the source object.
System.Windows.Controls.ValidationRule
System.Windows.Controls.DataErrorValidationRule
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
The DataErrorValidationRule type exposes the following members.
| Name | Description | |
|---|---|---|
 | DataErrorValidationRule | Initializes a new instance of the DataErrorValidationRule class. |
| Name | Description | |
|---|---|---|
| ValidatesOnTargetUpdated | Gets or sets a value that indicates whether the validation rule runs when the target of the Binding is updated. (Inherited from ValidationRule.) |
| ValidationStep | Gets or sets when the validation rule runs. (Inherited from ValidationRule.) |
| Name | Description | |
|---|---|---|
| Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
| Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
| GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| ToString | Returns a string that represents the current object. (Inherited from Object.) |
| Validate(Object, CultureInfo) | Performs validation checks on a value. (Overrides ValidationRule.Validate(Object, CultureInfo).) |
| Validate(Object, CultureInfo, BindingExpressionBase) | Performs validation checks on a value. (Inherited from ValidationRule.) |
| Validate(Object, CultureInfo, BindingGroup) | Performs validation checks on a value. (Inherited from ValidationRule.) |
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 Versions and Dependencies.
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> <!--By setting ValidatesOnExceptions to True, it checks for exceptions that are thrown during the update of the source property. An alternative syntax is to add <ExceptionValidationRule/> within the <Binding.ValidationRules> section.--> <Binding Path="Age" Source="{StaticResource data}" ValidatesOnExceptions="True" UpdateSourceTrigger="PropertyChanged"> <Binding.ValidationRules> <!--DataErrorValidationRule checks for validation errors raised by the IDataErrorInfo object.--> <!--Alternatively, you can set ValidationOnDataErrors="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.
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.
