Caliburn.Micro support for PasswordBox?

Question

The Caliburn.Micro homepage at http://caliburnmicro.com makes the following statement, but I cannot get CM to work with the PasswordBox control using any option I can think of from this example. You do not see how this will work in any case, since the names do not match. Does anyone have a CM example that allows me to get the PasswordBox value? Is a specific CM version required? I am running CM version 1.5.2. Ideally, without using Attached Properties, but if you can work with CM and only then it's fine. Please do not lecture on security issues as this is not a problem in my case.

---

Apply methods between your view and view model automatically using parameters and security methods

<StackPanel>
    <TextBox x:Name="Username" />
    <PasswordBox x:Name="Password" />
    <Button x:Name="Login" Content="Log in" />
</StackPanel>

public bool CanLogin(string username, string password)
{
    return !String.IsNullOrEmpty(username) && !String.IsNullOrEmpty(password);
}

public string Login(string username, string password)
{
    ...
}

Answer 1

I only managed to get it to work with dependency properties, effectively bypassing the good binding agreement that Caliburn.Micro provides. I admit that it is not your ideal, but pragmatically it is a solution that I regularly use. I believe that when I hit this trap historically, I found this post on StackOverflow that led me in that direction. For your consideration:

public class BoundPasswordBox
    {
        private static bool _updating = false;

        /// <summary>
        /// BoundPassword Attached Dependency Property
        /// </summary>
        public static readonly DependencyProperty BoundPasswordProperty =
            DependencyProperty.RegisterAttached("BoundPassword",
                typeof(string),
                typeof(BoundPasswordBox),
                new FrameworkPropertyMetadata(string.Empty, OnBoundPasswordChanged));

        /// <summary>
        /// Gets the BoundPassword property.
        /// </summary>
        public static string GetBoundPassword(DependencyObject d)
        {
            return (string)d.GetValue(BoundPasswordProperty);
        }

        /// <summary>
        /// Sets the BoundPassword property.
        /// </summary>
        public static void SetBoundPassword(DependencyObject d, string value)
        {
            d.SetValue(BoundPasswordProperty, value);
        }

        /// <summary>
        /// Handles changes to the BoundPassword property.
        /// </summary>
        private static void OnBoundPasswordChanged(
            DependencyObject d,
            DependencyPropertyChangedEventArgs e)
        {
            PasswordBox password = d as PasswordBox;
            if (password != null)
            {
                // Disconnect the handler while we're updating.
                password.PasswordChanged -= PasswordChanged;
            }

            if (e.NewValue != null)
            {
                if (!_updating)
                {
                    password.Password = e.NewValue.ToString();
                }
            }
            else 
            {
                password.Password = string.Empty;
            }
            // Now, reconnect the handler.
            password.PasswordChanged += PasswordChanged;
        }

        /// <summary>
        /// Handles the password change event.
        /// </summary>
        static void PasswordChanged(object sender, RoutedEventArgs e)
        {
            PasswordBox password = sender as PasswordBox;
            _updating = true;
            SetBoundPassword(password, password.Password);
            _updating = false;
        }
    }

Then in your XAML:

<PasswordBox pwbx:BoundPasswordBox.BoundPassword="{Binding UserPassword, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged,NotifyOnValidationError=True,ValidatesOnDataErrors=True}" />

and pwbx is located as the namespace in the Window tag:

<Window x:Class="MyProject.Views.LoginView"
             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" 
             xmlns:pwbx="clr-namespace:MyProject.Client.Controls">

ViewModel:

using Caliburn.Micro;
using MyProject.Core;
using MyProject.Repositories;
using MyProject.Types;
using MyProject.ViewModels.Interfaces;

namespace MyProject.ViewModels
{
    public class LoginViewModel : Screen, ILoginViewModel
    {
        private readonly IWindowManager _windowManager;
        private readonly IUnitRepository _unitRepository;
        public bool IsLoginValid { get; set; }
        public Unit LoggedInUnit { get; set; }

        private string _password;
        public string UserPassword
        {
            get { return _password; }
            set
            {
                _password = value;
                NotifyOfPropertyChange(() => UserPassword);
                NotifyOfPropertyChange(() => CanLogin);
            }
        }

        private string _name;
        public string Username
        {
            get { return _name; }
            set
            {
                _name = value;
                NotifyOfPropertyChange(() => Username);
                NotifyOfPropertyChange(() => CanLogin);
            }
        }
        public LoginViewModel(IWindowManager windowManager,IUnitRepository unitRepository)
        {
            _windowManager = windowManager;
            _unitRepository = unitRepository;
            DisplayName = "MyProject - Login";
            Version = ApplicationVersionRepository.GetVersion();
        }

        public string Version { get; private set; }

        public void Login()
        {
            // Login logic
            var credentials = new UserCredentials { Username = Username, Password=UserPassword };

            var resp = _unitRepository.AuthenticateUnit(credentials);
            if (resp == null) return;
            if (resp.IsValid)
            {
                IsLoginValid = true;
                LoggedInUnit = resp.Unit;
                TryClose();
            }
            else
            {
                var dialog = new MessageBoxViewModel(DialogType.Warning, DialogButton.Ok, "Login Failed", "Login Error: " + resp.InvalidReason);
                _windowManager.ShowDialog(dialog);
            }
        }

        public bool CanLogin
        {
            get
            {
                return !string.IsNullOrEmpty(Username) && !string.IsNullOrEmpty(UserPassword);
            }
        }
    }
}

Answer 2

, , PasswordBox Caliburn.Micro Just Works & trade;:

public static class PasswordBoxHelper
{
    public static readonly DependencyProperty BoundPasswordProperty =
        DependencyProperty.RegisterAttached("BoundPassword",
            typeof(string),
            typeof(PasswordBoxHelper),
            new FrameworkPropertyMetadata(string.Empty, OnBoundPasswordChanged));

    public static string GetBoundPassword(DependencyObject d)
    {
        var box = d as PasswordBox;
        if (box != null)
        {
            // this funny little dance here ensures that we've hooked the
            // PasswordChanged event once, and only once.
            box.PasswordChanged -= PasswordChanged;
            box.PasswordChanged += PasswordChanged;
        }

        return (string)d.GetValue(BoundPasswordProperty);
    }

    public static void SetBoundPassword(DependencyObject d, string value)
    {
        if (string.Equals(value, GetBoundPassword(d)))
            return; // and this is how we prevent infinite recursion

        d.SetValue(BoundPasswordProperty, value);
    }

    private static void OnBoundPasswordChanged(
        DependencyObject d,
        DependencyPropertyChangedEventArgs e)
    {
        var box = d as PasswordBox;

        if (box == null)
            return;

        box.Password = GetBoundPassword(d);
    }

    private static void PasswordChanged(object sender, RoutedEventArgs e)
    {
        PasswordBox password = sender as PasswordBox;

        SetBoundPassword(password, password.Password);

        // set cursor past the last character in the password box
        password.GetType().GetMethod("Select", BindingFlags.Instance | BindingFlags.NonPublic).Invoke(password, new object[] { password.Password.Length, 0 }); 
    }

}

:

public sealed class Bootstrapper : BootstrapperBase
{
    public Bootstrapper()
    {
        Initialize();

        ConventionManager.AddElementConvention<PasswordBox>(
            PasswordBoxHelper.BoundPasswordProperty,
            "Password",
            "PasswordChanged");
    }

    // other bootstrapper stuff here
}

Answer 3

.

Caliburn.Micro, ViewModel.

XAML:

<PasswordBox cal:Message.Attach="[Event PasswordChanged] = [Action OnPasswordChanged($source)]" />

ViewModel:

public void OnPasswordChanged(PasswordBox source)
{
    password = source.Password;
}

, .

. , ViewModel, , , , .

Answer 4

Sorry, I can not comment to reply due to low reputation. My question is: if I have 2 password fields, the second name is "ConfirmPassword", this will not raise the PasswordChanged event. Any help?

    <PasswordBox x:Name="Password" materialDesign:HintAssist.Hint="Password" Margin="0 10"
                 Style="{StaticResource MaterialDesignFloatingHintPasswordBox}"/>
    <PasswordBox materialDesign:HintAssist.Hint="Confirm Password" Margin="0 10"
                 Style="{StaticResource MaterialDesignFloatingHintPasswordBox}"/>

Answer 5

it worked perfectly. Thank you for that.