PasswordBox验证

Question

PasswordBox元素的Password属性不是文本，因此无法绑定(没有DependencyObject属性)。在用户键入时捕获密码是可能的，方法是将一条消息附加到PasswordChanged事件，传递源代码并在视图模型中获取它。然而，缺乏绑定意味着没有机会设置ValidatesOnDataErrors=True，因此IDataErrorInfo方法永远不会被调用，这意味着永远不会激活任何错误模板。有人知道怎么解决这个问题吗？也就是说，有没有其他方法可以让元素调用IDataErrorInfo索引器的视图模型？

一个合理的问题可能是，为什么要验证密码。

有两个原因：

1)让用户知道需要输入密码。

2)让用户知道密码和密码确认是否相同。

Answer 1

这里也有一个很好的提示：http://wpftutorial.net/PasswordBox.html，如果你这样做了，密码将以纯文本的形式存储在内存中。

也许更好的做法是将附加的属性"Password“从示例更改为"IsEmpty”和"PasswordHash“。

Answer 2

根据Alex下面的回答，我也使用了本文中的信息；

http://wpftutorial.net/PasswordBox.html

其中，我做了以下允许验证的操作；

XAML:

<Grid Grid.Row="2" Grid.Column="1">
    <TextBox x:Name="plain1" Text="{Binding Password, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True,NotifyOnValidationError=True}" Visibility="Hidden" />
    <PasswordBox x:Name="PasswordHelperBox" w:PasswordHelper.Attach="True" w:PasswordHelper.Password="{Binding Text, ElementName=plain1, Mode=TwoWay}" TabIndex="2" Margin="0,2,30,2"/>
</Grid>

其中"Password“是要绑定到的属性。

帮助器类；

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);
    }
}