合并的ObservableCollection [英] Merged ObservableCollection

问题描述

我有两个ObservableCollections，我需要一起显示在一个ListView控件。为此，我创建了MergedCollection，它将这两个集合作为一个ObservableCollection。这样我可以将ListView.ItemsSource设置为我的合并集合，并列出两个集合。添加工作正常，但是当我尝试删除一个项目，显示未处理的异常：

I have two ObservableCollections and I need to show them in one ListView control together. For this purpose I created MergedCollection which presents these two collections as one ObservableCollection. This way I can set the ListView.ItemsSource to my merged collection and both collections are listed. Adding works fine but when I try to Remove an item, unhandled exception is shown:

An unhandled exception of type 'System.InvalidOperationException' occurred in PresentationFramework.dll
Additional information: Added item does not appear at given index '2'.

MergedCollection的代码如下：

The code of MergedCollection follows:

public class MergedCollection : IEnumerable, INotifyCollectionChanged
{
    ObservableCollection<NetworkNode> nodes;
    ObservableCollection<NodeConnection> connections;

    public MergedCollection(ObservableCollection<NetworkNode> nodes, ObservableCollection<NodeConnection> connections)
    {
        this.nodes = nodes;
        this.connections = connections;

        this.nodes.CollectionChanged += new NotifyCollectionChangedEventHandler(NetworkNodes_CollectionChanged);
        this.connections.CollectionChanged += new NotifyCollectionChangedEventHandler(Connections_CollectionChanged);
    }

    void NetworkNodes_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        CollectionChanged(this, e);
    }

    void Connections_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        CollectionChanged(this, e);
    }

    #region IEnumerable Members

    public IEnumerator GetEnumerator()
    {
        for (int i = 0; i < connections.Count; i++)
        {
            yield return connections[i];
        }

        for (int i = 0; i < nodes.Count; i++)
        {
            yield return nodes[i];
        }
    }

    #endregion

    #region INotifyCollectionChanged Members

    public event NotifyCollectionChangedEventHandler CollectionChanged;

    #endregion
}

b $ b

推荐答案

有任何理由不能使用 CompositeCollection ？

异常被抛出的原因是因为你不会将内部集合的索引转换为外部集合。你只是将完全相同的事件args传递给外部事件（在 MergedCollection ），这就是为什么WPF找不到索引要找到的项目

The reason the exception is being thrown is because you're not translating the indexes of the inner collections to the outer. You're just passing the exact same event args to the outer event (on MergedCollection), which is why WPF doesn't find the items where the index is telling it to find them.

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