Delegate Command Example in MVVM

Introduction

The Delegate Command can be used by implementing the System.Windows.Input.ICommand interface, the following bellow code for use of delegate command :

XAML Code

<Window x:Class="CommandMVVM.View.CharacterView"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

mc:Ignorable="d"

d:DesignHeight="332" d:DesignWidth="477">

<Grid>

<Grid.ColumnDefinitions>

</Grid.ColumnDefinitions>

<Grid.RowDefinitions>

</Grid.RowDefinitions>

<ListBox Grid.Column="1" Grid.Row="3" Margin="5"

ItemsSource="{Binding Model.Powers}">

<ListBox.ItemTemplate>

</DataTemplate>

</ListBox.ItemTemplate>

</ListBox>

<!--<Button Grid.Column="1" Grid.Row="5" Content="Save"

Width="65" Height="25" HorizontalAlignment="Right"

Command="{Binding SaveCommand}"/>-->

<Button Grid.Column="1" Grid.Row="5" Content="{Binding SaveCommand2.Label}"

Width="65" Height="25" HorizontalAlignment="Right"

Command="{Binding SaveCommand2}"/>

</Grid>

</Window >

Add a new class in the ViewModes folder having following content

Code Behind

using System;

using System.Windows;

using CommandMVVM.Model;

using CommandMVVM.Framework;

namespace CommandMVVM.ViewModel

{

public class ComicCharacterViewModel : ObjectBase

{

public ComicCharacterViewModel()

: this(Character.Create())

{

}

public ComicCharacterViewModel(Character model)

{

Model = model;

SaveCommand = new SaveCharacterCommand(this);

SaveCommand2 = new DelegateCommand<object>(SaveCommand_Execute, SaveCommand_CanExecute);

}

public Character Model { get; private set; }

public SaveCharacterCommand SaveCommand { get; private set; }

public DelegateCommand<object> SaveCommand2 { get; private set; }

void SaveCommand_Execute(object arg)

{

// obviously this should not be done in the viewmodel

MessageBox.Show(string.Format("{0} character saved.", Model.Name));

}

bool SaveCommand_CanExecute(object arg)

{

return Model.Name != string.Empty;

}

For binding the ComicCharacterViewModel class to windows class write the following code in to the Initialized event

ViewModel.ComicCharacterViewModel CCVM = new ViewModel.ComicCharacterViewModel();
this.DataContext = CCVM;