docs-desktop/dotnet-desktop-guide/framework/wpf/data/how-to-implement-validation-logic-on-custom-objects.md

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title	ms.date	dev_langs	helpviewer_keywords	ms.assetid
How to: Implement Validation Logic on Custom Objects	08/02/2018	csharp vb	checking for validation errors [WPF] validation errors [WPF], checking for implementing validation logic on custom objects [WPF] custom objects [WPF], implementing validation logic on	751fda9b-44f9-4d63-b4f2-1df07ac41e0f

How to: Implement Validation Logic on Custom Objects

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

Example

You can provide validation logic on the business layer if your source object implements xref:System.ComponentModel.IDataErrorInfo, as in the following example, which defines a Person object that implements xref:System.ComponentModel.IDataErrorInfo:

[!code-csharpBusinessLayerValidation#IDataErrorInfo] [!code-vbBusinessLayerValidation#IDataErrorInfo]

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

[!code-xamlBusinessLayerValidation#BoundTextBox]

Alternatively, instead of using the xref:System.Windows.Controls.DataErrorValidationRule, you can set the xref:System.Windows.Data.Binding.ValidatesOnDataErrors%2A property to true.

See also

• xref:System.Windows.Controls.ExceptionValidationRule
• Implement Binding Validation
• How-to Topics