c# - 集合依赖项属性

我有一个自定义控件，该控件具有绑定(bind)到DependencyProperty的ObservableCollection类型的observableCollection:

<MyControl MyCollectionProperty = {Binding MyObservableCollection} ...

问题是添加到MyObservableCollection不会更新MyCollectionProperty。

我需要完全替换MyObservableCollection以使其正常工作，例如

MyObservableCollection = null;
MyObservableCollection = new ObservableCollection(){...}

有没有更好的方法来解决这个问题？

编辑:

    public ObservableCollection<string> Columns
    {
        get { return (ObservableCollection<string>)GetValue(ColumnsProperty); }
        set { SetValue(ColumnsProperty, value); }
    }

    public static readonly DependencyProperty ColumnsProperty =
        DependencyProperty.Register("Columns", typeof(ObservableCollection<string>), typeof(MyControl),
                                    new PropertyMetadata(new ObservableCollection<string>(), OnChanged));

最佳答案

下面是一个可能有用的工作示例。

在此示例中，当单击“添加”按钮时，将立即调用方法OnChanged，并将“更改”写入控制台。

控制

public class MyControl : Control
{

    public ObservableCollection<string> ExtraColumns
    {
        get { return (ObservableCollection<string>)GetValue(ExtraColumnsProperty); }
        set { SetValue(ExtraColumnsProperty, value); }
    }

    public static readonly DependencyProperty ExtraColumnsProperty =
        DependencyProperty.Register("ExtraColumns", typeof(ObservableCollection<string>), typeof(MyControl),
                                    new PropertyMetadata(new ObservableCollection<string>(), OnChanged));

    static void OnChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        (sender as MyControl).OnChanged();

    }

    void OnChanged()
    {
        if ( ExtraColumns != null )
            ExtraColumns.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(ExtraColumns_CollectionChanged);
    }

    void ExtraColumns_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
    {
        Console.WriteLine("Changed");
    }
}

window

<Window x:Class="WpfApplication18.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication18"
    Title="MainWindow" Height="350" Width="525">
  <StackPanel>
    <local:MyControl ExtraColumns="{Binding Extras}"/>
    <Button Click="Button_Click">Add</Button>
  </StackPanel>
</Window>

背后的窗口代码

public partial class MainWindow : Window
{
    private ObservableCollection<string> _extras = new ObservableCollection<string>( );
    public ObservableCollection<string> Extras
    {
        get { return _extras; }
        set
        {
            if (value != _extras)
            {
                _extras = value;
            }
        }
    }


    public MainWindow()
    {
        InitializeComponent();
        DataContext = this;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        Extras.Add("Additional");
    }
}

关于c# - 集合依赖项属性，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/15015217/