[c#] This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread



2 Answers

If I'm not mistaken, in WPF 4.5, you should be able to do this without any problem.

Now to solve this, you should use the synchronization context. Before you launch the thread, you have to store the synchronization context in the ui thread.

var uiContext = SynchronizationContext.Current;

Then you use it in your thread:

uiContext.Send(x => _matchObsCollection.Add(match), null);

Take a look at this tuto http://www.codeproject.com/Articles/31971/Understanding-SynchronizationContext-Part-I

Question

I have a DataGrid which is populating data from ViewModel by asynchronous method.My DataGrid is :

<DataGrid ItemsSource="{Binding MatchObsCollection}"  x:Name="dataGridParent" 
                      Style="{StaticResource EfesDataGridStyle}" 
                      HorizontalGridLinesBrush="#DADADA" VerticalGridLinesBrush="#DADADA" Cursor="Hand" AutoGenerateColumns="False" 
                      RowDetailsVisibilityMode="Visible"  >

I am using http://www.amazedsaint.com/2010/10/asynchronous-delegate-command-for-your.html to implement asynchronous way in my viewmodel.

Here is my viewmodel code:

public class MainWindowViewModel:WorkspaceViewModel,INotifyCollectionChanged
    {        

        MatchBLL matchBLL = new MatchBLL();
        EfesBetServiceReference.EfesBetClient proxy = new EfesBetClient();

        public ICommand DoSomethingCommand { get; set; }
        public MainWindowViewModel()
        {
            DoSomethingCommand = new AsyncDelegateCommand(
                () => Load(), null, null,
                (ex) => Debug.WriteLine(ex.Message));           
            _matchObsCollection = new ObservableCollection<EfesBet.DataContract.GetMatchDetailsDC>();                

        }       

        List<EfesBet.DataContract.GetMatchDetailsDC> matchList;
        ObservableCollection<EfesBet.DataContract.GetMatchDetailsDC> _matchObsCollection;

        public ObservableCollection<EfesBet.DataContract.GetMatchDetailsDC> MatchObsCollection
        {
            get { return _matchObsCollection; }
            set
            {
                _matchObsCollection = value;
                OnPropertyChanged("MatchObsCollection");
            }
        }        
        //
        public void Load()
        {            
            matchList = new List<GetMatchDetailsDC>();
            matchList = proxy.GetMatch().ToList();

            foreach (EfesBet.DataContract.GetMatchDetailsDC match in matchList)
            {
                _matchObsCollection.Add(match);
            }

        }

As you can see in my Load() method in my ViewModel first I am getting matchList (which is a list of a DataContract Class) from my Service.Then by foreach loop I am inserting my matchList items to my _matchObsCollection(which is an ObservableCollection of DataContract Class)).Now here I am getting the above error (as I shown in Title) "This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread"

Can anyone suggest me any solution.Moreover if possible I would like to know how to bind my DataGrid in View and also refresh it asynchronously if any better way is there.




In my case (I populate ObservableCollection with asynchronous tasks and do not have access to App instance) I use TaskScheduler.FromCurrentSynchronizationContext() to cleanup the collection on faulted:

        // some main task
        Task loadFileTask = Task.Factory.StartNew(...);

        Task cleanupTask = loadFileTask.ContinueWith(
            (antecedent) => { CleanupFileList(); },
            /* do not cancel this task */
            CancellationToken.None,
            /* run only if faulted main task */
            TaskContinuationOptions.OnlyOnFaulted,
            /* use main SynchronizationContext */
            TaskScheduler.FromCurrentSynchronizationContext());






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