TextBox uses the ExceptionValidationRule and UpdateSourceExceptionFilter handler : TextBox Validation « Windows Presentation Foundation « C# / CSharp Tutorial

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C# / CSharp Tutorial » Windows Presentation Foundation » TextBox Validation 
24.16.2.TextBox uses the ExceptionValidationRule and UpdateSourceExceptionFilter handler
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:c="clr-namespace:WpfApplication1"
  x:Class="WpfApplication1.Window1">
    <Window.Resources>
        <c:MyDataSource x:Key="ods"/>
        <ControlTemplate x:Key="validationTemplate">
            <DockPanel>
                <TextBlock Foreground="Red" FontSize="20">!</TextBlock>
                <AdornedElementPlaceholder/>
            </DockPanel>
        </ControlTemplate>
        <Style x:Key="textBoxInError" TargetType="{x:Type 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>
    </Window.Resources>
    <StackPanel>
        <TextBox Name="textBox3" Width="50" FontSize="15"
             Validation.ErrorTemplate="{StaticResource validationTemplate}"
             Style="{StaticResource textBoxInError}">
            <TextBox.Text>
                <Binding Path="Age3" Source="{StaticResource ods}" UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <ExceptionValidationRule/>
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>

        <CheckBox Name="cb" Checked="UseCustomHandler" Unchecked="DisableCustomHandler">Enable Custom Handler (see ToolTip)</CheckBox>
    </StackPanel>
</Window>

//File:Window.xaml.cs
using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Data;
using System.Globalization;
using System.Collections.ObjectModel;

namespace WpfApplication1
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        void UseCustomHandler(object sender, RoutedEventArgs e)
        {
            BindingExpression myBindingExpression = textBox3.GetBindingExpression(TextBox.TextProperty);
            Binding myBinding = myBindingExpression.ParentBinding;
            myBinding.UpdateSourceExceptionFilter = new UpdateSourceExceptionFilterCallback(ReturnExceptionHandler);
            myBindingExpression.UpdateSource();
        }

        void DisableCustomHandler(object sender, RoutedEventArgs e)
        {
            Binding myBinding = BindingOperations.GetBinding(textBox3, TextBox.TextProperty);
            myBinding.UpdateSourceExceptionFilter -= new UpdateSourceExceptionFilterCallback(ReturnExceptionHandler);
            BindingOperations.GetBindingExpression(textBox3, TextBox.TextProperty).UpdateSource();
        }

        object ReturnExceptionHandler(object bindingExpression, Exception exception)
        {
            return "This is from the UpdateSourceExceptionFilterCallBack.";
        }
    }
    public class AgeRangeRule : ValidationRule
    {
        private int _min;
        private int _max;

        public AgeRangeRule()
        {
        }

        public int Min
        {
            get return _min; }
            set _min = value; }
        }

        public int Max
        {
            get return _max; }
            set _max = value; }
        }

        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
        {
            int age = 0;

            try
            {
                if (((string)value).Length > 0)
                    age = Int32.Parse((String)value);
            }
            catch (Exception e)
            {
                return new ValidationResult(false, "Illegal characters or " + e.Message);
            }

            if ((age < Min|| (age > Max))
            {
                return new ValidationResult(false,
                  "Please enter an age in the range: " + Min + " - " + Max + ".");
            }
            else
            {
                return new ValidationResult(true, null);
            }
        }
    }

    public class MyDataSource
    {
        private int _age;
        private int _age2;
        private int _age3;

        public MyDataSource()
        {
            Age = 0;
            Age2 = 0;
        }

        public int Age
        {
            get return _age; }
            set _age = value; }
        }
        public int Age2
        {
            get return _age2; }
            set _age2 = value; }
        }

        public int Age3
        {
            get return _age3; }
            set _age3 = value; }
        }
    }
}
WPF Text Box Uses The Exception Validation Rule And Update Source Exception Filter Handler
24.16.TextBox Validation
24.16.1.TextBox with custom ErrorTemplate and ToolTipTextBox with custom ErrorTemplate and ToolTip
24.16.2.TextBox uses the ExceptionValidationRule and UpdateSourceExceptionFilter handlerTextBox uses the ExceptionValidationRule and UpdateSourceExceptionFilter handler
24.16.3.TextBox with UpdateSourceExceptionFilter handlerTextBox with UpdateSourceExceptionFilter handler
24.16.4.TextBox with default ErrorTemplateTextBox with default ErrorTemplate
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