WPF_Practice/PacticeSolution/BindingValidationRuleSample/MainWindow.xaml

<Window x:Class="BindingValidationRuleSample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:BindingValidationRuleSample"
        xmlns:model="clr-namespace:BindingValidationRuleSample.Model"
        xmlns:validation="clr-namespace:BindingValidationRuleSample.Validation"
        mc:Ignorable="d"
        Title="MainWindow" Height="200" Width="300">
    <Window.DataContext>
        <model:Student/>
    </Window.DataContext>

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <TextBlock Grid.Column="0" Grid.Row="0" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="10,2"
                   Text="Name: "/>
        <TextBlock Grid.Column="0" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="10,2"
                   Text="Age: "/>
        <TextBlock Grid.Column="0" Grid.Row="2" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="10,2"
                   Text="Phone Number: "/>

        <TextBox Grid.Column="1" Grid.Row="0" Margin="5"
                 Text="{Binding Name, Mode=TwoWay}"/>
        <TextBox x:Name="tbxAge" Grid.Column="1" Grid.Row="1" Margin="5"
                 ToolTip="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}">
            <TextBox.Text>
                <Binding Path="Age"
                         Mode="TwoWay"
                         UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <validation:AgeRangeException/>
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
        <TextBox Grid.Column="1" Grid.Row="2" Margin="5" Foreground="Blue"
                 Text="{Binding PhoneNumber, Mode=TwoWay}"/>

        <Grid Grid.Column="0" Grid.Row="4" Grid.ColumnSpan="2" Height="30">
            <Grid.ColumnDefinitions>
                <ColumnDefinition/>
                <ColumnDefinition/>
                <ColumnDefinition/>
                <ColumnDefinition/>
            </Grid.ColumnDefinitions>

            <Button Grid.Column="2" Content="OK" Margin="5 3"
                    Foreground="{Binding ElementName=tbxAge, Path=Foreground}"/>
            <Button Grid.Column="3" Content="Cancel" Margin="5 3"/>
        </Grid>
    </Grid>
</Window>