This is second part of my article where I talk about Validation in WPF using Entlib Validation Application Block. First part of my article is located on this location : https://www.radenkozec.com/post/2009/07/07/WPF-Validation-using-Validation-Application-Block-41-Part-1-e28093-Server-side/

There are many articles about client side validation in WPF. Most of these articles are similar and use implementation of IDataErrorInfo interface on Model class.

I have use some methods  already described in other articles just to show you how easy it is to implement client side validation in WPF using VAB.

I have model class called Customer where I have implemented IDataErrorInfo. Code looks like this :

public string Error
{
get {
StringBuilder error = new StringBuilder();
ValidationResults results = Validation.ValidateFromAttributes<Customer>(this);
foreach (ValidationResult result in results)
{
error.AppendLine(result.Message);
}
return error.ToString() ;
}
}
public string this[string columnName]
{
get {
ValidationResults results = Validation.ValidateFromAttributes<Customer>(this);
foreach (ValidationResult result in results)
{
if (result.Key == columnName)
{
return result.Message;
}
}
return string.Empty;
}
}

I have called ValidateFromAttributes method of Validation class that exists in VAB to get collection of ValidationResults. It is easy as that.

In Application.Resources of my WPF application I have defined some textbox error template and style to use when validation error is occurred. For this I have borrowed some code from other articles to save on time writing templates and styles.

And final in xaml on textboxes I have added following code where I have turn on Validation and defined witch error template to use :

<TextBox x:Name="txtFirstName"  Grid.Column="1"  TextWrapping="Wrap" 
Text="{Binding FirstName, ValidatesOnDataErrors=True}" Validation.ErrorTemplate="{StaticResource TextBoxErrorTemplate}" />

References :

http://msdn.microsoft.com/en-us/magazine/cc700358.aspx

http://www.eggheadcafe.com/tutorials/aspnet/f726cd7d-cfcc-43c3-85d8-2afc75e7a08a/wpf-input-validation-with.aspx