Validation By Exception (Display Error message by ToolTip) in Wpf using MVVM

View

<Window x:Class="WpfPrismTutorial.Views.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:WpfPrismTutorial"
        mc:Ignorable="d"
        prism:ViewModelLocator.AutoWireViewModel="True"
        xmlns:prism="http://prismlibrary.com/"
        xmlns:valid="clr-namespace:WpfPrismTutorial.Validations"
        Title="MainWindow" Height="450" Width="800">

    <Grid VerticalAlignment="Center" HorizontalAlignment="Left">
     
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="Validation by Exception" Margin="5,5"/>
             <TextBox Text="{Binding MainWindowModel.ValidationByException,UpdateSourceTrigger=PropertyChanged,
                        ValidatesOnExceptions=True}" x:Name="txt"  Height="30" Width="300">
                <TextBox.Style>
                    <Style TargetType="TextBox" BasedOn="{StaticResource {x:Type TextBox}}">
                        <Style.Triggers>
                            <Trigger  Property="Validation.HasError" Value="true">
                                <Setter Property="ToolTip" Value="Invalid input"/>
                            </Trigger>
                        </Style.Triggers>
                    </Style>
                </TextBox.Style>
            </TextBox>
        </StackPanel>
     
    </Grid>
</Window>

ViewModel 

 public class MainWindowViewModel : BindableBase

    {

        private MainWindowModel mainWindowModel = new MainWindowModel();

        public MainWindowModel MainWindowModel

        {

            get { return mainWindowModel; }

            set { SetProperty(ref mainWindowModel, value); }

        }

    }

Model

 public class MainWindowModel : BindableBase
    {
        #region Validation By Exception

        private string _validationByException = string.Empty;

        public string ValidationByException
        {
            get { return _validationByException; }
            set

            {
                if (string.IsNullOrEmpty(value))
                    throw new Exception("Validation By Exception should not empty");
                SetProperty(ref _validationByException, value);
            }
        }
        #endregion
    }