How to create TextBox in wpf that does not accept number using MVVM?

Method 1: Using Model Property

Inside View

<TextBox Width="200" Text="{Binding MainWindowModel.NonNumeric,UpdateSourceTrigger=PropertyChanged}">

Inside Model

 private string _nonNumeric;

        public string NonNumeric
        {
            get { return _nonNumeric; }
            set
            {
                int intvalue;
                if (!int.TryParse(value[value.Length - 1].ToString(), out intvalue))
                    SetProperty(ref _nonNumeric, value);
                else
                    value = _nonNumeric;
            }

        }

Method 2 : Using Command

Inside View

<Window x:Class="PrismDemo.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:PrismDemo.Views"
        mc:Ignorable="d" xmlns:prism="http://prismlibrary.com/"
        xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity">
<Grid>
 <TextBox Width="200">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="KeyDown">
                    <prism:InvokeCommandAction Command="{Binding KeyDownCommand}" />
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </TextBox>
</Grid>
</Window>

Inside ViewModel

 public MainWindowViewModel()
        {
             KeyDownCommand = new DelegateCommand<KeyEventArgs>(ExecuteKeyDownMenu);
        }
  private void ExecuteKeyDownMenu(KeyEventArgs e)
        {
            if (e.Key >= Key.D0 && e.Key <= Key.D9)
            {
                e.Handled = true;
            }
        }


        public ICommand KeyDownCommand { get; set; }