Caliburn.Micro 是否支持 PasswordBox？

Question

http://caliburnmicro.com 的 Caliburn.Micro 主页提出以下声明，但我无法使用从该示例中想到的任何变体使 CM 与 PasswordBox 控件一起使用。无论如何都看不到这将如何工作，因为名称的大小写不同。有没有人有一个 CM 示例可以让我获得 PasswordBox 的值？是否需要特定版本的 CM？我正在运行 CM 的 1.5.2 版。理想情况下不使用附加属性，但如果可以使用 CM 并且唯一的方法就可以了。请不要就安全问题进行讲座，因为这对我来说不是问题。

---

使用参数和保护方法自动在视图和视图模型之间应用方法

<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

这是一个更加简化的示例，包括一个绑定约定，以便在 Caliburn.Micro Just Works™ 中绑定 PasswordBox：

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 }); 
    }

}

然后，在您的引导程序中：

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

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

    // other bootstrapper stuff here
}

Answer 2

这里提供的解决方案似乎是不必要的复杂。

我们可以非常轻松地使用 Caliburn.Micro 操作将我们的密码发送到 ViewModel。

XAML：

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

视图模型：

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

然后记得清除密码字段，以免它们留在内存中。

注意：显然，此解决方案不允许您从 ViewModel 轻松更改密码，如果有必要，那么最好使用附加属性方法。

Answer 3

我只能让它与依赖属性一起工作，有效地绕过了 Caliburn.Micro 提供的约定绑定优点。我承认这不是您的理想，但实际上这是我经常使用的解决方案。我相信当我在历史上遇到这个障碍时，我在 StackOverflow 上找到了 this post，这使我朝着这个方向前进。供您参考：

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;
        }
    }

然后，在您的 XAML 中：

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

并且 pwbx 在 Window 标签上作为命名空间被发现：

<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">

视图模型：

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);
            }
        }
    }
}