在Silverlight中使用INotifyPropertyChanged绑定到字典

在Silverlight中，我无法让INotifyPropertyChanged像绑定到字典时那样工作。在下面的例子中，页面绑定到字典好，但是当我更改其中一个文本框的内容时，不会调用CustomProperties属性设置器。 CustomProperties属性设置器仅在设置了CustomProperties时调用，而不是在其中设置值时调用。我正在尝试对字典值进行一些验证，因此当字典中的每个值发生更改时，都希望运行一些代码。我能在这里做什么吗？在Silverlight中使用INotifyPropertyChanged绑定到字典

C＃

public partial class MainPage : UserControl 
{ 

    public MainPage() 
    { 
     InitializeComponent(); 

     MyEntity ent = new MyEntity(); 
     ent.CustomProperties.Add("Title", "Mr"); 
     ent.CustomProperties.Add("FirstName", "John"); 
     ent.CustomProperties.Add("Name", "Smith"); 

     this.DataContext = ent; 
    } 

} 

public class MyEntity : INotifyPropertyChanged 
{ 

    public event PropertyChangedEventHandler System.ComponentModel.INotifyPropertyChanged.PropertyChanged; 
    public delegate void PropertyChangedEventHandler(object sender, System.ComponentModel.PropertyChangedEventArgs e); 

    private Dictionary<string, object> _customProps; 
    public Dictionary<string, object> CustomProperties { 
     get { 
      if (_customProps == null) { 
       _customProps = new Dictionary<string, object>(); 
      } 
      return _customProps; 
     } 
     set { 
      _customProps = value; 
      if (PropertyChanged != null) { 
       PropertyChanged(this, new PropertyChangedEventArgs("CustomProperties")); 
      } 
     } 
    } 

}

Partial Public Class MainPage 
    Inherits UserControl 

    Public Sub New() 
     InitializeComponent() 

     Dim ent As New MyEntity 
     ent.CustomProperties.Add("Title", "Mr") 
     ent.CustomProperties.Add("FirstName", "John") 
     ent.CustomProperties.Add("Name", "Smith") 

     Me.DataContext = ent 
    End Sub 

End Class 

Public Class MyEntity 
    Implements INotifyPropertyChanged 

    Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged 

    Private _customProps As Dictionary(Of String, Object) 
    Public Property CustomProperties As Dictionary(Of String, Object) 
     Get 
      If _customProps Is Nothing Then 
       _customProps = New Dictionary(Of String, Object) 
      End If 
      Return _customProps 
     End Get 
     Set(ByVal value As Dictionary(Of String, Object)) 
      _customProps = value 
      RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("CustomProperties")) 
     End Set 
    End Property 

End Class

的XAML

<TextBox Height="23" Name="TextBox1" Text="{Binding Path=CustomProperties[Title], Mode=TwoWay}" /> 
<TextBox Height="23" Name="TextBox2" Text="{Binding Path=CustomProperties[FirstName], Mode=TwoWay}" /> 
<TextBox Height="23" Name="TextBox3" Text="{Binding Path=CustomProperties[Name], Mode=TwoWay}" />

来源

2010-04-14 Carl Rippon

集合需要实现INotifyCollectionChanged interface除了INotifyPropertyChanged interface支持数据绑定。 ObservableCollection class为类似列表的集合实现它们，但我相信在.NET Framework中没有像字典一样的集合。你可能必须自己实现它。

来源

2010-04-14 11:24:25 dtb

谢谢，我tweeked dr wpf的ObservableDictionary的实现：http://drwpf.com/blog/2007/09/16/can-i-bind-my-itemscontrol-to-a-dictionary/ – 2010-04-14 12:58:27

这是一个（有点过于简单化）的解决方案。

public class MyEntity : INotifyPropertyChanged 
{ 

    public event PropertyChangedEventHandler PropertyChanged; 

    private readonly Dictionary<string, object> _customProps = new Dictionary<string, object>(); 

    public void AddCustomProperty(string key, object value) 
    { 
     _customProps.Add(key, value); 
    } 

    public object this[string key] 
    { 
     get { return _customProps[key]; } 
     set 
     { 
      // The validation code of which you speak here. 
      _customProps[key] = value; 
      NotifyPropertyChanged("Item[" + key "]"); 
     } 
    } 

    private void NotifyPropertyChanged(string name) 
    { 
     if (PropertyChanged != null) 
      PropertyChanged(this, new PropertyChangedEventArgs(name)); 
    } 
}

的MainPage： -

public MainPage() 
    { 
     InitializeComponent(); 

     MyEntity ent = new MyEntity(); 
     ent.AddCustomProperty("Title", "Mr"); 
     ent.AddCustomProperty("FirstName", "John"); 
     ent.AddCustomProperty("Name", "Smith"); 

     this.DataContext = ent; 

    }

的MainPage XAML中： -

 <TextBox Height="23" Name="TextBox1" Text="{Binding [Title], Mode=TwoWay}" /> 
     <TextBox Height="23" Name="TextBox2" Text="{Binding [FirstName], Mode=TwoWay}" /> 
     <TextBox Height="23" Name="TextBox3" Text="{Binding [Name], Mode=TwoWay}" />

针对您的问题，重要的是你的代码中包含的属性值到字典中的分配。原来你的代码暴露了Dictionary，所有的分配工作都经过了框架组件代码。在此版本中，MyEntity具有字符串索引器，其中自定义属性直接分配并且Dictionary被设置为私有。

注意INotifyPropertyChanged的执行并不是严格需要回答你的具体问题，但我怀疑你会需要它。例如，如果你重新分配一个新的值给一个自定义属性，你会希望UI被通知。

来源

2010-04-14 12:42:17 AnthonyWJones

在Silverlight中使用INotifyPropertyChanged绑定到字典

回答

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