Bind the Button to a Command : Command « Windows Presentation Foundation « C# / CSharp Tutorial






<Window x:Class="WpfApplication1.Window1"
   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
   Title="WPF" Height="240" Width="300">
    <StackPanel>
        <TextBlock Text="First Name"/>
        <TextBox   Text="{Binding Path=FirstName}"/>
        <TextBlock Text="Age"/>
        <TextBox Text="{Binding Path=Age}"/>
        
        <Button Command="{Binding Path=Add}" Content="Add"/>
        <ComboBox x:Name="cboOccupation" IsEditable="False" Width="100">
             <ComboBoxItem>Student</ComboBoxItem>
             <ComboBoxItem>Skilled</ComboBoxItem>
             <ComboBoxItem>Professional</ComboBoxItem>
        </ComboBox>
        <Button Command="{Binding Path=SetOccupation}" CommandParameter="{Binding ElementName=cboOccupation, Path=Text}" Content="Set Occupation"/>
        <TextBlock Text="Status"/>
        <TextBlock Text="{Binding Path=Status, UpdateSourceTrigger=PropertyChanged}"/>
        
    </StackPanel>
</Window>

//File:Window.xaml.cs

using System.Windows;
using System;
using System.ComponentModel;
using System.Windows.Input;
namespace WpfApplication1
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            this.DataContext = new Employee(){FirstName = "A"};
        }
    }
    public class Employee : INotifyPropertyChanged
    {
        private string firstName;
        private int age;
        private string occupation;
        private string status;

        private AddEmployeeCommand addEmployeeCommand;
        private SetOccupationCommand setOccupationCommand;
        public string Status
        {
            get
            {
                return status;
            }
            set
            {
                if(status!= value)
                {
                    status= value;
                    OnPropertyChanged("Status");
                }
            }
        }
        public string FirstName
        {
            get
            {
                return firstName;
            }
            set
            {
                if(firstName != value)
                {
                    firstName = value;
                    OnPropertyChanged("FirstName");
                }
            }
        }
        public int Age
        {
            get
            {
                return age;
            }
            set
            {
                if(this.age != value)
                {
                    this.age = value;
                    OnPropertyChanged("Age");
                }
            }
        }
        public string Occupation
        {
            get
            {
                return occupation;
            }
            set
            {
                if(this.occupation != value)
                {
                    this.occupation = value;
                    OnPropertyChanged("Occupation");
                }
            }
        }
        public AddEmployeeCommand Add
        {
            get
            {
                if(addEmployeeCommand == null)
                    addEmployeeCommand = new AddEmployeeCommand(this);

                return addEmployeeCommand;
            }
        }
        public SetOccupationCommand SetOccupation
        {
            get
            {
                if(setOccupationCommand == null)
                    setOccupationCommand = new SetOccupationCommand(this);

                return setOccupationCommand;
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string propertyName)
        {
            if(this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }

    public class AddEmployeeCommand : ICommand
    {
        private Employee person;

        public AddEmployeeCommand(Employee person)
        {
            this.person = person;

            this.person.PropertyChanged += new PropertyChangedEventHandler(person_PropertyChanged);
        }

        private void person_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            if(CanExecuteChanged != null)
            {
                CanExecuteChanged(this, EventArgs.Empty);
            }
        }
        public bool CanExecute(object parameter)
        {
            if(!string.IsNullOrEmpty(person.FirstName))
               if(person.Age > 0)
                    if(string.IsNullOrEmpty(person.Status))
                            return true;

            return false;
        }

        public event EventHandler CanExecuteChanged;

        public void Execute(object parameter)
        {
            person.Status = string.Format("Added {0}", person.FirstName);
        }
    }

    public class SetOccupationCommand : ICommand
    {
        private Employee person;

        public SetOccupationCommand(Employee person)
        {
            this.person = person;

            this.person.PropertyChanged += new PropertyChangedEventHandler(person_PropertyChanged);
        }

        private void person_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            if(CanExecuteChanged != null)
            {
                CanExecuteChanged(this, EventArgs.Empty);
            }
        }

        public bool CanExecute(object parameter)
        {
            if(!string.IsNullOrEmpty(parameter as string))
                if(!string.IsNullOrEmpty(person.Status))
                    return true;

            return false;
        }

        public event EventHandler CanExecuteChanged;

        public void Execute(object parameter)
        {
            person.Occupation = parameter.ToString();

            person.Status = string.Format("Added {0},{1}", person.FirstName, person.Occupation);
        }
    }
}
WPF Bind The Button To A Command








24.135.Command
24.135.1.Built-In Command BindingsBuilt-In Command Bindings
24.135.2.Help commandHelp command
24.135.3.Button CommandTarget BindingButton CommandTarget Binding
24.135.4.Creating CommandBinding and attaching an Executed and CanExecute handlerCreating CommandBinding and attaching an Executed and CanExecute handler
24.135.5.Creating a KeyBinding between the Open command and Ctrl-RCreating a KeyBinding between the Open command and Ctrl-R
24.135.6.Command Handler Command Binding in XamlCommand Handler Command Binding in Xaml
24.135.7.Command Handler Key BindingCommand Handler Key Binding
24.135.8.Bind the Button to a CommandBind the Button to a Command
24.135.9.Command EnablingCommand Enabling
24.135.10.Using CommandBinding and ExecutedRoutedEventHandler to bind Application event to an event handler methodUsing CommandBinding and ExecutedRoutedEventHandler to bind Application event to an event handler method
24.135.11.Create CommandBindings in Xaml and bind to ButtonCreate CommandBindings in Xaml and bind to Button
24.135.12.Bind TextBox save command to CommandBindingBind TextBox save command to CommandBinding
24.135.13.Use TextBox.CommandBindingst to bind commandUse TextBox.CommandBindingst to bind command
24.135.14.Parse command line arguments and make them available to an application.Parse command line arguments and make them available to an application.
24.135.15.Handle a Button Click with Shared button click handlerHandle a Button Click with Shared button click handler
24.135.16.File Menu, new MenuItemFile Menu, new MenuItem
24.135.17.Cancel an eventCancel an event
24.135.18.Bind the command to the event handlers with CommandBindings