我该如何在WPF中将数据绑定到仅有getter而没有setter的属性,并从视图模型中访问它?我正在使用 PasswordBox
并希望将其 SecureString
属性绑定到ViewModel属性。我该怎么做?
我该如何在WPF中将数据绑定到仅有getter而没有setter的属性,并从视图模型中访问它?我正在使用 PasswordBox
并希望将其 SecureString
属性绑定到ViewModel属性。我该怎么做?
并且我使用了 System.Windows.Interactivity 库。
public sealed class PropertyManager : TriggerAction<FrameworkElement>
{
#region Fields
private bool _bindingUpdating;
private PropertyInfo _currentProperty;
private bool _propertyUpdating;
#endregion
#region Dependency properties
/// <summary>
/// Identifies the <see cref="Binding" /> dependency property.
/// </summary>
public static readonly DependencyProperty BindingProperty =
DependencyProperty.Register("Binding", typeof(object), typeof(PropertyManager),
new PropertyMetadata((o, args) =>
{
var propertyManager = o as PropertyManager;
if (propertyManager == null ||
args.OldValue == args.NewValue) return;
propertyManager.TrySetProperty(args.NewValue);
}));
/// <summary>
/// Identifies the <see cref="SourceProperty" /> dependency property.
/// </summary>
public static readonly DependencyProperty SourcePropertyProperty =
DependencyProperty.Register("SourceProperty", typeof(string), typeof(PropertyManager),
new PropertyMetadata(default(string)));
/// <summary>
/// Binding for property <see cref="SourceProperty" />.
/// </summary>
public object Binding
{
get { return GetValue(BindingProperty); }
set { SetValue(BindingProperty, value); }
}
/// <summary>
/// Name property to bind.
/// </summary>
public string SourceProperty
{
get { return (string)GetValue(SourcePropertyProperty); }
set { SetValue(SourcePropertyProperty, value); }
}
#endregion
#region Methods
/// <summary>
/// Invokes the action.
/// </summary>
/// <param name="parameter">
/// The parameter to the action. If the action does not require a parameter, the parameter may be
/// set to a null reference.
/// </param>
protected override void Invoke(object parameter)
{
TrySetBinding();
}
/// <summary>
/// Tries to set binding value.
/// </summary>
private void TrySetBinding()
{
if (_propertyUpdating) return;
PropertyInfo propertyInfo = GetPropertyInfo();
if (propertyInfo == null) return;
if (!propertyInfo.CanRead)
return;
_bindingUpdating = true;
try
{
Binding = propertyInfo.GetValue(AssociatedObject, null);
}
finally
{
_bindingUpdating = false;
}
}
/// <summary>
/// Tries to set property value.
/// </summary>
private void TrySetProperty(object value)
{
if (_bindingUpdating) return;
PropertyInfo propertyInfo = GetPropertyInfo();
if (propertyInfo == null) return;
if (!propertyInfo.CanWrite)
return;
_propertyUpdating = true;
try
{
propertyInfo.SetValue(AssociatedObject, value, null);
}
finally
{
_propertyUpdating = false;
}
}
private PropertyInfo GetPropertyInfo()
{
if (_currentProperty != null && _currentProperty.Name == SourceProperty)
return _currentProperty;
if (AssociatedObject == null)
throw new NullReferenceException("AssociatedObject is null.");
if (string.IsNullOrEmpty(SourceProperty))
throw new NullReferenceException("SourceProperty is null.");
_currentProperty = AssociatedObject
.GetType()
.GetProperty(SourceProperty);
if (_currentProperty == null)
throw new NullReferenceException("Property not found in associated object, property name: " +
SourceProperty);
return _currentProperty;
}
#endregion
}
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:behaviors="clr-namespace:YOUR NAMESPACE WHERE YOU PUT THE PropertyManager CLASS"
您还需要指定要更新值的事件,在本例中为PasswordChanged
,并指定您要绑定的属性,在本例中为Password
:
<PasswordBox>
<i:Interaction.Triggers>
<i:EventTrigger EventName="PasswordChanged">
<behaviors:PropertyManager
Binding="{Binding Path=MyPasswordProperty, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
SourceProperty="Password" />
</i:EventTrigger>
</i:Interaction.Triggers>
</PasswordBox>
这个类功能强大,可以与任何属性一起使用,并支持双向绑定。
XAML中的绑定:
<PasswordBox Text="{Binding SecureString, Mode=OneWay}"...
如果你不想从XAML绑定中更改它
public string SecureString
{
get { return _secureString;}
private set
{
if(_secureString == value) return;
_secureString = value;
RaisePropertyChanged(() => SecureString);
}
public void SetSecureString(string newSecureString)
{
SecureString = newSecureString;
}
PasswordBox
控件上的SecureString
属性是只读属性,这意味着你无法从标记或代码中设置它。 - Ibrahim NajjarPasswordBox
从XAML设置一个类型为SecureString
的属性到你的视图模型吗? - Ibrahim Najjar