如何处理ObservableCollection<>由MVVM中的并行任务导致的？ [英] How to handle ObservableCollection<> result from a parallelized Task in MVVM?

问题描述

我正在单独的任务中收集数据，我想使用 ObservableCollection<> 将数据绑定到GUI组件。所以我的代码是这样的：

  private ObservableCollection< MyItem> _items; 
 public ObservableCollection< MyItem>项目
 {
 get {return _items; } 
 set 
 {
 if（_items.Equals（value））
 {
 return; 
} 
 _items = value; 
 RaisePropertyChanged（Items）; 
} 
} 
 
 private void LoadData（）
 {
任务任务= Task.Factory.StartNew（（）=> 
 {
 ObservableCollection< MyItem> itms = _htmlParser.FetchData（...）; 
 
 Dispatcher.CurrentDispatcher.Invoke（（Action）委托
 {
 Items = itms ; 
}）; 
}）; 
} 
  

从执行某些HTTP请求的组件中获取数据。我得到的错误是：

必须在DependencyObject的同一线程上创建DependencySource。

我正在使用MVVM Light工具箱框架。我也试图发送结果作为一个消息，但最终在同一个错误消息。任何想法或指针？

编辑：这是问题：

  public class MyItem 
 {
 public string Id {get;组; } 
 public string Name {get;组; } 
 public BitmapImage Image {get;组; } //< ---一个大的否否，因为它继承自DependencyObject 
 public Uri Uri {get;组; 
} 
  

我更改了 BitmapImage 到 byte [] 数据类型。

解决方案

异常你得到（必须在DependencyObject的同一个线程上创建DependencySource）表示在后台线程上创建的东西并在UI线程上使用。是否有任何UI控件被创建并存储在集合中以供UI使用？

我看到ObservableCollection本身是在后台线程上创建的，但是我不要以为是这个问题 - 不幸的是我不在办公室进行编码并确认。

I am gathering data in a separate Task and I want to data bind the result to a GUI component using an ObservableCollection<>. So my code goes something like this:

private ObservableCollection<MyItem> _items;
public ObservableCollection<MyItem> Items
{
  get { return _items; }
  set
  {
    if (_items.Equals(value))
    {
      return;
    }
    _items = value;
    RaisePropertyChanged("Items");
  }
}

private void LoadData()
{
  Task task = Task.Factory.StartNew(() =>
  {
    ObservableCollection<MyItem> itms = _htmlParser.FetchData(...);

    Dispatcher.CurrentDispatcher.Invoke((Action)delegate
    {
      Items = itms;
    });
  });
}

The data is fetched from a component doing some HTTP requests. The error I am getting is:
Must create DependencySource on same Thread as the DependencyObject.

I am using the MVVM Light toolkit framework. I also tried to send the result as a message, but that ended up in the same error message. Any ideas or pointers?

EDIT: Here's the issue:

public class MyItem
{
  public string Id { get; set; }
  public string Name { get; set; }
  public BitmapImage Image { get; set; }  // <--- A big No No because it inherits from the DependencyObject
  public Uri Uri { get; set; }
}

I changed the BitmapImage to a byte[] data type.

解决方案

The exception you're getting ("Must create DependencySource on same Thread as the DependencyObject") indicates that something's being created on a background thread and used on the UI thread. Are there any UI controls being created and stored in the collection for use by the UI?

I see that the ObservableCollection itself is being created on a background thread, but I don't think that's the issue -- unfortunately I'm not in the office to code and confirm that.

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