button on xaml launches server side launch of csv file download.

06-23-2009 3:09 PM |

given the following sequence of client side call to a server side csv file creation, what do I have to do in the way of a web control or container to accomodate the HttpContext.Current.ApplicationInstance.CompleteRequest(); statement at the bottom of this post. I would expect a dialog box appear on the "web container" to launch a dialog box to save the file just created to the client's machine. Thank you !

  private void Button_Click(object sender, RoutedEventArgs e)
  {
    if (HtmlPage.Window.Confirm("Save report contents to Excel?"))
   {
      proxy.ExportDataTableToCSVCompleted += new EventHandler (proxy_ExportDataTableToCSVCompleted);
      proxy.ExportDataTableToCSVAsync();

 WILL CALL THE FOLLOWING SERVER SIDE METHOD

    #region "Export DataTable To CSV"
    [OperationContract]
    public void ExportDataTableToCSV()
    {
            DataTable dt = new DataTable();
            string strSQL = "---sql statement -----";
            SqlCommand command = new SqlCommand(strSQL, conn);
            SqlDataAdapter da = new SqlDataAdapter(command);
            string filename = "test.csv";
            exportDataTableToCsv(dt, filename);

 WHICH CALLS ANOTHER SERVER SIDE METHOD

    private void exportDataTableToCsv(DataTable formattedDataTable, string filename)
    {
            DataTable toExcel = formattedDataTable.Copy();
            HttpContext context = HttpContext.Current;
            context.Response.Clear();

            foreach (DataColumn column in toExcel.Columns)
            {
                context.Response.Write(column.ColumnName + ",");
            }

            context.Response.Write(Environment.NewLine);
            foreach (DataRow row in toExcel.Rows)
            {
                for (int i = 0; i < toExcel.Columns.Count; i++)
                {
                    context.Response.Write(row.ToString().Replace(",", string.Empty) + ",");
                }

                context.Response.Write(Environment.NewLine);
            }

            context.Response.ContentType = "text/csv";
            context.Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename + ".csv");
            HttpContext.Current.ApplicationInstance.CompleteRequest();

Re: button on xaml launches server side launch of csv file download.

06-23-2009 11:21 PM |

It would be much easier to save the file to the server and then display a link to download the newly created file that the user can then click on. You could launch the download in a new window if you wanted.

I am not sure sending a response will work since silverlight is actually running in a seperate context...

Re: button on xaml launches server side launch of csv file download.

06-24-2009 8:07 AM |

Thank you !

How would I display a link to download the newly created file? 

Or launch in new window given I just took your recommendation on the save file to server thought as pe the following.  Thanks!

            void WriteFile(StringBuilder stringCSV)
            {
                string FileLocation = "C:\\";
                string FileName = "testfile.csv";
                FileStream fileStream = null;
                StreamWriter writer = null;
                 try
                 {
                    fileStream = new FileStream(FileLocation +
                              FileName, FileMode.OpenOrCreate,
                              FileAccess.Write);
                  writer = new StreamWriter(fileStream);

                  // Force the write to the underlying file
                  writer.WriteLine(stringCSV.ToString());
                  writer.Flush();
                 }
                 finally
                 {
                  if( writer != null ) writer.Close();
                 }
            }

Re: Re: button on xaml launches server side launch of csv file download.

06-24-2009 12:50 PM |

Thank you. That sounds like a clear set of instructions. I'll report back as soon as i have a chance to code and test.

Re: Re: Re: button on xaml launches server side launch of csv file download.

06-24-2009 1:10 PM |

Sounds good, if you get stuck let me know and I will see if I can whip up an example.

Re: Re: Re: button on xaml launches server side launch of csv file download.

06-29-2009 8:14 AM |

I marked your idea as the answer..... but I haven't implemented yet...... is the purpose of the _blank to launch a popup for the user to save the file whose url has been returned from the service?  Thanks for your patience !

Re: Re: Re: button on xaml launches server side launch of csv file download.

06-30-2009 4:47 PM |

Yes the _blank will launch a new window. I am not 100% sure this is needed, but was trying to avoid the application refreshing and loosing any state that might be there. You can try it without the _blank target to see if it refreshes or not.