PasswordBox绑定

Question

我刚开始使用M-V-VM和WPF和了解一些有约束力的问题，有问题。

我有具有ComboBox和PasswordBox登录页面。所述ComboBox看起来像这样：

<ComboBox Name="comboBox1" SelectedItem="{Binding Path=Username}">

这工作就好了 - ！我的价值观得到更新，每次在SelectedItem的ComboBox修改

在我的视图模型我有使用这种方法的ICommand以确定是否登录按钮处于活动状态：

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

所以我的问题是我没有绑定到视图模型Password属性的PasswordBox - 所以我没有办法知道，当它被更新

。

那么，如何让PasswordBox的到我的视图模型的价值？我读过的一切只是说，不绑定出于安全原因PasswordBox。我将简单地摘下的CanLogin（密码限制），但我需要的值以沿着到的AccountService通过。

Answer 1

有趣。

看这个博客帖子，看看它是否帮助你。 http://blog.functionalfun.net/2008/06 /wpf-passwordbox-and-data-binding.html

显然的链路是死现在所以这里原始溶液（实测这里）：

可以使用附加属性来创建这样的助手：

public static class PasswordHelper
{
    public static readonly DependencyProperty PasswordProperty =
        DependencyProperty.RegisterAttached("Password",
        typeof(string), typeof(PasswordHelper),
        new FrameworkPropertyMetadata(string.Empty, OnPasswordPropertyChanged));

    public static readonly DependencyProperty AttachProperty =
        DependencyProperty.RegisterAttached("Attach",
        typeof(bool), typeof(PasswordHelper), new PropertyMetadata(false, Attach));

    private static readonly DependencyProperty IsUpdatingProperty =
       DependencyProperty.RegisterAttached("IsUpdating", typeof(bool), 
       typeof(PasswordHelper));


    public static void SetAttach(DependencyObject dp, bool value)
    {
        dp.SetValue(AttachProperty, value);
    }

    public static bool GetAttach(DependencyObject dp)
    {
        return (bool)dp.GetValue(AttachProperty);
    }

    public static string GetPassword(DependencyObject dp)
    {
        return (string)dp.GetValue(PasswordProperty);
    }

    public static void SetPassword(DependencyObject dp, string value)
    {
        dp.SetValue(PasswordProperty, value);
    }

    private static bool GetIsUpdating(DependencyObject dp)
    {
        return (bool)dp.GetValue(IsUpdatingProperty);
    }

    private static void SetIsUpdating(DependencyObject dp, bool value)
    {
        dp.SetValue(IsUpdatingProperty, value);
    }

    private static void OnPasswordPropertyChanged(DependencyObject sender,
        DependencyPropertyChangedEventArgs e)
    {
        PasswordBox passwordBox = sender as PasswordBox;
        passwordBox.PasswordChanged -= PasswordChanged;

        if (!(bool)GetIsUpdating(passwordBox))
        {
            passwordBox.Password = (string)e.NewValue;
        }
        passwordBox.PasswordChanged += PasswordChanged;
    }

    private static void Attach(DependencyObject sender,
        DependencyPropertyChangedEventArgs e)
    {
        PasswordBox passwordBox = sender as PasswordBox;

        if (passwordBox == null)
            return;

        if ((bool)e.OldValue)
        {
            passwordBox.PasswordChanged -= PasswordChanged;
        }

        if ((bool)e.NewValue)
        {
            passwordBox.PasswordChanged += PasswordChanged;
        }
    }

    private static void PasswordChanged(object sender, RoutedEventArgs e)
    {
        PasswordBox passwordBox = sender as PasswordBox;
        SetIsUpdating(passwordBox, true);
        SetPassword(passwordBox, passwordBox.Password);
        SetIsUpdating(passwordBox, false);
    }
}

使用它：

<PasswordBox w:PasswordHelper.Attach="True" 
             w:PasswordHelper.Password="{Binding Text, ElementName=plain, Mode=TwoWay}" 
             Width="100"/>

Answer 2

我发布了GIST 此处这是一个可绑定密码框。