Data export fails: Please provide writable stream for export!

[Nicole]

Hello,

I'm trying to export my GridView to csv and I'm getting the following error: Please provide writable stream for export!

   bei Telerik.Windows.Controls.GridView.GridViewDataControl.Export(Stream stream, GridViewExportOptions options) in c:\TB\221\WPF_Scrum\Release_WPF\Sources\Development\Controls\GridView\GridView\GridView\Exporting\GridViewDataControl.Exporting.cs:Zeile 17.
   bei Data_Transfer_GUI.GridViewExportProvider.<>c__DisplayClass6.<Export>b__0()
   bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)


This is my code:

var grid = pExportObject as RadGridView;
if (grid != null)
{
    string extension = "csv";
    var dialog = new SaveFileDialog();
    dialog.DefaultExt = extension;
    dialog.Filter = "CSV (*.csv)|*.csv";
    dialog.FilterIndex = 1;

    var format = ExportFormat.Html;

    if (dialog.ShowDialog() == true)
    {
        FileInfo fi = new FileInfo(dialog.FileName);

        switch (fi.Extension)
        {
            case ".xls":
                format = ExportFormat.Html;
                break;
            case ".xml":
                format = ExportFormat.ExcelML;
                break;
            case ".doc":
                format = ExportFormat.Html;
                break;
            case ".csv":
                format = ExportFormat.Csv;
                break;
        }

        using (var stream = dialog.OpenFile())
        {
            var exportOptions = new GridViewExportOptions();
            exportOptions.Format = format;
            exportOptions.ShowColumnFooters = true;
            exportOptions.ShowColumnHeaders = true;
            exportOptions.ShowGroupFooters = true;

            try
            {
                // Check if this thread has access to this object.
                grid.Dispatcher.VerifyAccess();

                // The thread has access to the object, so update the UI.
                grid.Export(stream, exportOptions);
            }
            // Cannot access objects on the thread.
            catch (InvalidOperationException ex)
            {
                // Placing job onto the Dispatcher of the UI Thread.
                grid.Dispatcher.BeginInvoke(DispatcherPriority.Normal,
                    new Action(() => grid.Export(stream, exportOptions)));
            }

        }
    }

The error occurs at this line:

grid.Dispatcher.BeginInvoke(DispatcherPriority.Normal,
    new Action(() => grid.Export(stream, exportOptions)));

When I hover the stream and open the tooltip I see that
stream.Length' threw an exception of type 'System.ObjectDisposedException'

Second thing is, that I can't understand why the InvalidOperationException is raised. The GridView is on the UI-Thread. It should be not necessary to invoke here. The export is called from a simple command which is called from the UI--Thread.

Do you have an idea why this all happens?

Thank you very much!
Kind regards

[Dimitrina]

Hello,

I am not able to reproduce any issue on the WPF Demos. Would you please check what do you do differently for your solution? 

Kind regards,
Didie
the Telerik team

[Nicole]

Hello Didie,

thank you for your answer.

I have an update:
When I hover the stream and open the tooltip I see that
stream.Length' threw an exception of type 'System.ObjectDisposedException'

How could  that be? Is the export method asynchron?

[Dimitrina]

Hi,

What if you remove this line:

grid.Dispatcher.VerifyAccess();

Then you can also set the stream position back to start:

stream.Position = 0

I am not able to reproduce such an issue locally when following the approach from the Exporting demo.

Regards,
Didie
Telerik