command

PacticeSolution/CommandSample/App.xaml

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+<Application x:Class="CommandSample.App"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:local="clr-namespace:CommandSample"
+             StartupUri="MainWindow.xaml">
+    <Application.Resources>
+         
+    </Application.Resources>
+</Application>

PacticeSolution/CommandSample/App.xaml.cs

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+using System;
+using System.Collections.Generic;
+using System.Configuration;
+using System.Data;
+using System.Linq;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace CommandSample
+{
+    /// <summary>
+    /// Interaction logic for App.xaml
+    /// </summary>
+    public partial class App : Application
+    {
+    }
+}

PacticeSolution/CommandSample/AssemblyInfo.cs

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+using System.Windows;
+
+[assembly: ThemeInfo(
+    ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
+                                     //(used if a resource is not found in the page,
+                                     // or application resource dictionaries)
+    ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
+                                              //(used if a resource is not found in the page,
+                                              // app, or any theme specific resource dictionaries)
+)]

PacticeSolution/CommandSample/CommandSample.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net6.0-windows</TargetFramework>
+    <Nullable>enable</Nullable>
+    <UseWPF>true</UseWPF>
+  </PropertyGroup>
+
+</Project>

PacticeSolution/CommandSample/Commands/MessageCommand.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Input;
+
+namespace CommandSample.Commands
+{
+    internal class MessageCommand : ICommand
+    {
+        private Action<string> _execute;
+        private Predicate<string> _canExecute;
+
+        public event EventHandler? CanExecuteChanged
+        {
+            add { CommandManager.RequerySuggested += value; }
+            remove { CommandManager.RequerySuggested -= value; }
+        }
+
+        public MessageCommand(Action<string> execute, Predicate<string> canExecute)
+        {
+            _execute = execute;
+            _canExecute = canExecute;
+        }
+
+        public bool CanExecute(object? parameter)
+        {
+            bool result = _canExecute.Invoke(parameter as string);
+            return result;
+        }
+
+        public void Execute(object? parameter)
+        {
+            if (_execute == null)
+                return;
+
+            _execute.Invoke(parameter as string);
+        }
+    }
+}

PacticeSolution/CommandSample/MainWindow.xaml

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+<Window x:Class="CommandSample.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:CommandSample"
+        xmlns:vm="clr-namespace:CommandSample.ViewModels"
+        mc:Ignorable="d"
+        Title="MainWindow" Height="300" Width="300">
+    <Window.DataContext>
+        <vm:MessageViewModel/>
+    </Window.DataContext>
+    
+    <StackPanel>
+        <TextBox x:Name="tbMain"/>
+        <Button Content="Click" 
+                Command="{Binding DisplayMessageCommand}"
+                CommandParameter="{Binding ElementName=tbMain, Path=Text}"/>
+    </StackPanel>
+</Window>

PacticeSolution/CommandSample/MainWindow.xaml.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+
+namespace CommandSample
+{
+    /// <summary>
+    /// Interaction logic for MainWindow.xaml
+    /// </summary>
+    public partial class MainWindow : Window
+    {
+        public MainWindow()
+        {
+            InitializeComponent();
+        }
+    }
+}

PacticeSolution/CommandSample/ViewModels/MessageViewModel.cs

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+using CommandSample.Commands;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace CommandSample.ViewModels
+{
+    internal class MessageViewModel
+    {
+        public MessageCommand DisplayMessageCommand { get; set; }
+
+        public MessageViewModel()
+        {
+            this.DisplayMessageCommand = new MessageCommand(DisplayMessage, AddMessage);
+        }
+
+        public void DisplayMessage(string param)
+        {
+            MessageBox.Show($"Clicked! (Param: {param})");
+        }
+
+        public bool AddMessage(string param)
+        {
+            if (string.IsNullOrEmpty(param))
+                return false;
+
+            return true;
+        }
+    }
+}