Understanding Commands in WPF: A Cleaner Alternative to Button Click Events

Many WPF developers start by using Button Click events for handling user actions. At first, this seems simple and straightforward. But very soon, the code-behind file becomes huge , and maintaining it turns into a challenge. One big problem arises: when the logic changes, the button does not enable or disable automatically , and testing button click logic becomes very difficult. So the big question is: Is there a better way to handle button actions in WPF? The answer is Commands . In this post, we’ll learn how to use Commands in WPF with a simple, practical example. We’ll cover: What a Command is How it works Why using Commands is better than Click events How buttons can automatically enable or disable based on conditions What is a Command in WPF? In WPF, a Command acts as a middle layer between the UI and your logic. Instead of the button directly calling a method, it triggers a Command , and the Command decides: What code should run Whether the button s...
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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
    }

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