使用INotifyPropertyChanged绑定到Silverlight中的字典 [英] Binding to a dictionary in Silverlight with INotifyPropertyChanged

问题描述

在silverlight中，我不能让INotifyPropertyChanged工作，就像我想要绑定到一个字典时一样。在下面的示例中，页面绑定到字典可以，但是当我更改其中一个文本框的内容时，CustomProperties属性设置器不被调用。 CustomProperties属性设置程序仅在设置CustomProperties时调用，而不是设置其中的值时调用。我正在尝试对字典值进行一些验证，因此我希望在字典中的每个值都更改时运行一些代码。在这里有什么我可以做吗？

In silverlight, I can not get INotifyPropertyChanged to work like I want it to when binding to a dictionary. In the example below, the page binds to the dictionary okay but when I change the content of one of the textboxes the CustomProperties property setter is not called. The CustomProperties property setter is only called when CustomProperties is set and not when the values within it are set. I am trying to do some validation on the dictionary values and so am looking to run some code when each value within the dictionary is changed. Is there anything I can do here?

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"));
            }
        }
    }

}

VB

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

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}" />

推荐答案

集合需要实现 INotifyCollectionChanged界面除了 INotifyPropertyChanged界面来支持数据绑定。 ObservableCollection class 实现了它们的列表类集合，但我相信在.NET Framework中没有这样的字典集合。你可能必须自己实现。

A collection needs to implement the INotifyCollectionChanged interface in addition to the INotifyPropertyChanged interface to support data binding. The ObservableCollection class implements them for a List-like collection, but I believe there is no dictionary-like collection in the .NET Framework that does this. You likely have to implement it yourself.

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