如何从 INotifyPropertyChanged PropertyChanged 事件的发送者对象获取属性名称

Question

我有一个 DependencyObject 基类，其中有一个方法接受对象、获取属性，并且对于属于实现 INotifyPropertyChanged 的​​类型的每个属性，我添加一个新的 PropertyChangedEventHandler。现在，在处理程序方法中，它获取对象“sender”的参数和PropertyChangedEventArgs“e”。我的问题是，如果 sender 是实现 INotifyPropertyChanged 的​​类型的属性，有谁知道如何动态获取属性名称。

这是我正在处理的内容：

public class BaseDependencyObject : DependencyObject, INotifyPropertyChanged
{
    public BaseDependencyObject()
    {

    }

    protected void SetValues(Object thisObject, Object entity)
    {
        try
        {
            PropertyInfo[] properties = entity.GetType().GetProperties();
            foreach (PropertyInfo property in properties)
            {
                var value = property.GetValue(entity, null);
                var valueIsEntity = value is System.ServiceModel.DomainServices.Client.Entity;
                var thisObjectsProperty = thisObject.GetType().GetProperty(property.Name);

                if (thisObjectsProperty != null && value != null)
                {
                    if (valueIsEntity)
                    {
                        if (thisObjectsProperty.PropertyType.GetInterface("INotifyPropertyChanged", true) != null)
                        {
                            var propertyInstance = Activator.CreateInstance(thisObjectsProperty.PropertyType);

                            ((INotifyPropertyChanged)propertyInstance).PropertyChanged += new PropertyChangedEventHandler(Object_PropertyChanged);
                        }

                        SetValues(thisObjectsProperty, value);
                    }

                    else if (thisObjectsProperty.PropertyType.GetInterface("ICollection", true) != null
                        && thisObjectsProperty.PropertyType.GetGenericArguments().Count() > 0)
                    {
                        Type genericType = thisObjectsProperty.PropertyType.GetGenericArguments()[0];

                        var observableCollection = Activator.CreateInstance(thisObjectsProperty.PropertyType) as IList;

                        if (observableCollection is INotifyCollectionChanged)
                            ((INotifyCollectionChanged)observableCollection).CollectionChanged += this.Object_CollectionChanged;

                        if (observableCollection is INotifyPropertyChanged)
                            ((INotifyPropertyChanged)observableCollection).PropertyChanged += new PropertyChangedEventHandler(Object_PropertyChanged);

                        foreach (var item in (IEnumerable)value)
                        {
                            var newItem = Activator.CreateInstance(genericType);

                            if (newItem != null)
                            {
                                SetValues(newItem, item);
                                observableCollection.Add(newItem);
                            }
                        }
                    }

                    else
                    {
                        thisObjectsProperty.SetValue(thisObject, value, null);

                    }
                }
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    protected void Object_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        switch (e.Action)
        {
            case NotifyCollectionChangedAction.Add:
                foreach (var item in e.NewItems)
                {
                    if (item is INotifyPropertyChanged)
                    {
                        ((INotifyPropertyChanged)item).PropertyChanged += new PropertyChangedEventHandler(Object_PropertyChanged);
                    }
                }
                break;

            case NotifyCollectionChangedAction.Remove:
                foreach (var item in e.OldItems)
                {
                    if (item is INotifyPropertyChanged)
                    {
                        ((INotifyPropertyChanged)item).PropertyChanged -= this.Object_PropertyChanged;
                    }
                }
                break;
        }

    }

    protected void Object_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        this.NotifyPropertyChanged(e.PropertyName);
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void NotifyPropertyChanged(string propertyName)
    {
        var handler = PropertyChanged;

        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));

    }
}

SetValues 方法的第一个参数是将在视图模型中使用的 DependencyObject 类型。第二个参数是从 DomainService 的 Context.LoadOperation 返回的实体。

我的问题归结为当 INotifyCollectionChanged.CollectionChanged 触发时我需要能够使用集合的属性名称引发 PropertyChanged 事件。因此，如果有人有任何建议，我将不胜感激。提前致谢。

编辑
弄清楚如何获取触发事件的属性名称。这是我的 PropertyChangedEventHandler 的编辑版本。

protected void Object_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        var properties = this.GetType().GetProperties().Where(x => x.PropertyType == sender.GetType()).ToArray();

        foreach (var property in properties)
        {
            this.NotifyPropertyChanged(property.Name);
        }

        //this.NotifyPropertyChanged(e.PropertyName);
    }

基本上这就是我想要的，但显然我仍然没有做正确的事情。当添加另一种类型的属性 ObservableCollection 时，UIElement 仍未更新。

这是我的 DependencyObjects 和 ViewModel 的示例：

public class LOB : DependencyObject
{
    public Int32 ID
    {
        get { return (Int32)GetValue(IDProperty); }
        set
        {
            SetValue(IDProperty, value);
            NotifyPropertyChanged("ID");
        }
    }

    public static readonly DependencyProperty IDProperty =
    DependencyProperty.Register("ID", typeof(Int32), typeof(LOB), null);

    public ObservableCollection<Group> Groups
    {
        get { return (ObservableCollection<Group>)GetValue(GroupsProperty); }
        set
        {
            SetValue(GroupsProperty, value);
            NotifyPropertyChanged("Groups");
        }
    }

    public static readonly DependencyProperty GroupsProperty =
    DependencyProperty.Register("Groups", typeof(ObservableCollection<Group>), typeof(LOB), new PropertyMetadata(null, OnGroupsPropertyChanged));

    static void OnGroupsPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
    {
        if (e.NewValue != null)
        {
            ((INotifyCollectionChanged)e.NewValue).CollectionChanged += new NotifyCollectionChangedEventHandler(((LOB)obj).Object_CollectionChanged);
            ((INotifyPropertyChanged)e.NewValue).PropertyChanged += new PropertyChangedEventHandler(((LOB)obj).Object_PropertyChanged);
        }
        if (e.OldValue != null)
        {
            ((INotifyCollectionChanged)e.OldValue).CollectionChanged -= ((LOB)obj).Object_CollectionChanged;
            ((INotifyPropertyChanged)e.OldValue).PropertyChanged -= ((LOB)obj).Object_PropertyChanged;
        }
    }

}

public class Group : DependencyObject
{
    public Int32 ID
    {
        get { return (Int32)GetValue(IDProperty); }
        set
        {
            SetValue(IDProperty, value);
            NotifyPropertyChanged("ID");
        }
    }

    public static readonly DependencyProperty IDProperty =
    DependencyProperty.Register("ID", typeof(Int32), typeof(Group), null);

    public String GroupName
    {
        get { return (String)GetValue(GroupNameProperty); }
        set
        {
            SetValue(GroupNameProperty, value);
            NotifyPropertyChanged("GroupName");
        }
    }

    public static readonly DependencyProperty GroupNameProperty =
    DependencyProperty.Register("GroupName", typeof(String), typeof(Group), null);

}

public class MyViewModel : DependencyObject
{
    public static readonly DependencyProperty LobCollectionProperty =
        DependencyProperty.Register("LobCollection",
            typeof(ObservableCollection<LOB>),
            typeof(MyViewModel),
            new PropertyMetadata(null, LobCollectionPropertyChanged));

    public ObservableCollection<LOB> LobCollection
    {
        get { return (ObservableCollection<MainBusinessLine>)GetValue(LobCollectionPropertyChanged); }
        set
        {
            SetValue(MainBusinessLineCollectionProperty, value);
            NotifyPropertyChanged("LobCollection");
        }
    }

    static void LobCollectionPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
    {
        var viewModel = obj as MyViewModel;

        if (viewModel == null)
            return;

        if (e.OldValue != null)
        {
            ((INotifyCollectionChanged)e.OldValue).CollectionChanged -= viewModel.LobCollection_Changed;
        }

        if (e.NewValue != null)
        {
            ((INotifyCollectionChanged)e.NewValue).CollectionChanged += viewModel.LobCollection_Changed;
        }

    }

    void LobCollection_Changed(object sender, NotifyCollectionChangedEventArgs e)
    {
        NotifyPropertyChanged("LobCollection");
    }
}  

Answer 1

经过上面的对话，这是相当没有意义的，但我考虑了如何实现一个基类，当子类定义的属性中的集合发生更改时，该基类会触发 PropertyChanged 事件。正如我所说，这有点不标准，但我是这样做的。

class FancyCollectionAndPropertyChangedBase : INotifyPropertyChanged
{
    private Dictionary<ICollectionChanged, String> collectionNameLookup = new Dictionary<ICollectionChanged, String>();

    protected FancyCollectionAndPropertyChangedBase()
    {
        this.PropertyChanged += MyPropertyChanged;
    }

    private void MyPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if(this.collectionNameLookup.ContainsValue(e.PropertyName)
        {
            KeyValuePair<INotifyCollectionChanged, String> oldValue = this.collectionNameLookup.First(kvp => kvp.Value == e.Name);
            oldValue.Key -= MyCollectionChanged;
            this.collecitonNameLookup.Remove(oldValue.Key);

            INotifyCollectionChanged collection = this.GetType().GetProperty(e.PropertyName, BindingFlags.FlattenHierarchy).GetValue(this, null);
            collection.CollectionChanged += MyCollectionChanged;
            this.collectionNameLookup.Add(collection, e.Name);
        }
        else if(typeof(INotifyCollectionChanged).IsAssignableFrom(this.GetType().GetProperty(e.PropertyName,  BindingFlags.FlattenHierarchy).PropertyType))
        {
            // Note: I may have gotten the IsAssignableFrom statement, above, backwards. 
            INotifyCollectionChanged collection = this.GetType().GetProperty(e.PropertyName, BindingFlags.FlattenHierarchy).GetValue(this, null);
            collection.CollectionChanged += MyCollectionChanged;
            this.collectionNameLookup.Add(collection, e.Name);
        }
    }

    private void MyCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        this.NotifyPropertyChanged(this.collectionNameLookup[sender];
    }
}