Asynchronous data loading with Entity Data Source?

[Samuel]

I have a GridView where the ItemsSource is bound to the PagedSource property of a DataPager.  The DataPager ItemsSource is bound to an EntityDataSource.  The problem is that this is blocking my UI thread.  The GridView has a "DataLoadMode" property which can be set to Asynchronous... but the pager doesn't.  How would I go about loading the data to the pager asynchronously?  I tried doing this in another thread but I keep getting a cross-thread exception even though I use the dispatcher to set the property to which the pager is bound.

 

<telerik:RadGridView x:Name="RadGridView1"
                                         Grid.Row="0"
                                         Margin="5,5,5,0"
                                         HorizontalAlignment="Stretch"
                                         VerticalAlignment="Stretch"
                                         AlternateRowBackground="LightBlue"
                                         AlternationCount="2"
                                         AutoGenerateColumns="False"
                                         CanUserDeleteRows="False"
                                         CanUserFreezeColumns="False"
                                         CanUserInsertRows="False"
                                         DataLoadMode="Asynchronous"
                                         GroupRenderMode="Nested"
                                         IsReadOnly="True"
                                         ItemsSource="{Binding ElementName=DataPager1,
                                                               Path=PagedSource}"
                                         RowIndicatorVisibility="Collapsed"
                                         ShowGroupPanel="False"
                                         telerik:StyleManager.Theme="Summer">
                        <telerik:RadGridView.Columns>

                            <telerik:GridViewDataColumn Width="60"
                                                        DataMemberBinding="{Binding StoreNumber}"
                                                        Header="Store"
                                                        ShowDistinctFilters="True"
                                                        ShowFieldFilters="False"
                                                        TextAlignment="Center" />

                            <telerik:GridViewDataColumn Width="80"
                                                        DataFormatString="dd-MMM-yyyy"
                                                        DataMemberBinding="{Binding ASNDate}"
                                                        Header="Ship Date"
                                                        ShowDistinctFilters="False"
                                                        SortingState="Descending"
                                                        TextAlignment="Center" />

                            <telerik:GridViewDataColumn Width="Auto"
                                                        MinWidth="80"
                                                        DataMemberBinding="{Binding PONumber}"
                                                        Header="PO"
                                                        ShowDistinctFilters="False"
                                                        TextAlignment="Center" />

                            <telerik:GridViewDataColumn Width="80"
                                                        DataFormatString="dd-MMM-yyyy"
                                                        DataMemberBinding="{Binding PODate}"
                                                        Header="PO Date"
                                                        ShowDistinctFilters="False"
                                                        TextAlignment="Center" />

                            <telerik:GridViewDataColumn Width="Auto"
                                                        MinWidth="80"
                                                        DataMemberBinding="{Binding InvoiceNumber}"
                                                        Header="Invoice"
                                                        ShowDistinctFilters="False"
                                                        TextAlignment="Center" />

                            <telerik:GridViewDataColumn Width="Auto"
                                                        DataMemberBinding="{Binding ToteID}"
                                                        Header="Tote"
                                                        ShowDistinctFilters="True"
                                                        TextAlignment="Center">
                                <telerik:GridViewDataColumn.CellTemplate>
                                    <DataTemplate>
                                        <TextBlock Width="Auto"
                                                   Height="Auto"
                                                   HorizontalAlignment="Center"
                                                   VerticalAlignment="Center">
                                            <Hyperlink Click="OnToteClick" Tag="{Binding}">
                                                <TextBlock Width="Auto"
                                                           Height="Auto"
                                                           HorizontalAlignment="Center"
                                                           VerticalAlignment="Center"
                                                           Text="{Binding ToteID}" />
                                            </Hyperlink>
                                        </TextBlock>
                                    </DataTemplate>
                                </telerik:GridViewDataColumn.CellTemplate>
                            </telerik:GridViewDataColumn>

                            <telerik:GridViewDataColumn Width="80"
                                                        DataFormatString="dd-MMM-yyyy"
                                                        DataMemberBinding="{Binding Closed}"
                                                        Header="Completed"
                                                        ShowDistinctFilters="False" />

                            <telerik:GridViewDataColumn Width="Auto"
                                                        DataMemberBinding="{Binding ClosedByName}"
                                                        Header="Complete By"
                                                        ShowDistinctFilters="True"
                                                        ShowFieldFilters="False"
                                                        TextAlignment="Center" />

                        </telerik:RadGridView.Columns>
                    </telerik:RadGridView>

                    <telerik:RadDataPager x:Name="DataPager1"
                                          Grid.Row="1"
                                          Width="{Binding ActualWidth,
                                                          ElementName=RadGridView1}"
                                          Margin="5,0,5,5"
                                          DisplayMode="FirstLastPreviousNextNumeric"
                                          PageSize="{Binding PageSize,
                                                             Mode=TwoWay}"
                                          Source="{Binding ShipmentData}"
                                          telerik:StyleManager.Theme="Summer" />

 

public class ShipmentsViewModel : ViewModelBase
    {
        private readonly TIMS.Data.TIMSContext ctx =new Data.TIMSContext();

        public ShipmentsViewModel()
        {

        }

        #region Properties

        private int PageSizeValue = 20;
        public int PageSize
        {
            get { return PageSizeValue; }
            set
            {
                SetPropertyValue((() => PageSize), ref PageSizeValue, value);
            }
        }


        private QueryableEntityCollectionView<TIMS.Data.Entities.ToteView> ShipmentDataValue;
        public QueryableEntityCollectionView<TIMS.Data.Entities.ToteView> ShipmentData
        {
            get {
                    return ShipmentDataValue;
            }
            private set
            {
                SetPropertyValue((() => ShipmentData), ref ShipmentDataValue, value);
            }
        }

        #endregion

        #region Methods

        public override void OnNavigatedTo(Uri view, object data)
        {
            try
            {
                IsBusy = true;
                System.Threading.ThreadPool.QueueUserWorkItem(delegate
                {
                    var shipments = new QueryableEntityCollectionView<Data.Entities.ToteView>(((IObjectContextAdapter)ctx).ObjectContext, "ToteViews");
                    if (App.Store != null)
                    {
                        shipments.FilterDescriptors.Add(new FilterDescriptor("StoreNumber", FilterOperator.IsEqualTo, App.Store.Value, false));
                    }


                    App.Current.Dispatcher.Invoke(new Action(delegate
                    {
                        ShipmentDataValue = shipments;
                        IsBusy = false;
                    }));

                });
            }
            catch (Exception e)
            {
                App.Current.Dispatcher.BeginInvoke(new Action(delegate
                {
                    var dlg = new ChildWindows.ErrorDialog("0012:  An unknown error occured.");
                    App.LogError(e);
                    dlg.ShowDialog();
                    IsBusy = false;
                }));
            }
        }

        #endregion

        #region Commands


        #endregion
    }

[Dimitrina]

Hello,

For the time being, RadEntityFrameworkDataSource does not support async loading. I have made a Feature Request on this public: Asynchronous support.
You can vote for it and also follow the item to get notified once there is a change in its Status.

For the time being, I can suggest you considering RadDataServiceDataSource, which handles all operations asynchronously. 

Regards,
Dimitrina
Telerik