PasswordBox绑定

Question

我刚开始使用MV-VM和WPF,并且遇到了解一些绑定问题的问题.

我有一个登录页面,其中包含a ComboBox和a PasswordBox.该ComboBox如下所示:

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

这工作得很好 - 每次SelectedItem更改时我的值都会更新ComboBox!

在我的ViewModel中,我有一个ICommand使用此方法来确定Login按钮是否处于活动状态:

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

所以我的问题是我没有PasswordBox绑定ViewModel上的Password属性 - 所以我没有办法告诉它什么时候更新.

那么如何获取PasswordBoxViewModel 的值呢？我读过的所有内容都说不出PasswordBox于安全原因而绑定.我只是取消了CanLogin()的密码限制,但我需要将值传递给AccountService.

Answer 1

有趣.

看看这篇博客文章,看看它是否对你有帮助. http://blog.functionalfun.net/2008/06/wpf-passwordbox-and-data-binding.html

显然链接现在已经死了,所以这里是原始解决方案(在此处找到):

您可以使用附加属性来创建这样的帮助:

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);
    }
}

用它:

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

Answer 2

我在这里发布了一个GIST ,它是一个可绑定的密码框.