Missing Parameters when using .PrintToPrinter or .ExportToDisk

Question

I am creating a viewer that will set login information and allow the users to view, print or export reports.  VB.NET 2010 WinForms Crystal Engine 13.0.9.1312.  All reports are external designed by various programmers.
The preview mode of my viewer is now working quite well (with the help of Don and Ludek most recently).  Anything I want to see on screen works great in the regular Crystal viewer.
The problem is when I want to export to pdf or print to a printer without viewing on screen in the regular Crystal viewer.
If there are no parameters in the reports, both exporting to pdf and printing to any printer selected works.
When there is one or more parameters, it crashes and points to the line
crReport.ExportToDisk(ExportFormatType.PortableDocFormat, strFile)
or
crReport.PrintToPrinter(1, True, 0, 0)
with the message Missing Parameter Values.
Through some searching (and yes I have checked on this site and Google for "Missing Parameter Values") I have found one big issue is that parameter values have to be set after the .ReportSource is set.  So before I changed my code, I never saw the Crystal Parameter prompt screen.  Now I see it but still get the crash (though once I have had it go to printer honouring the Parameter in a report, but I can't always reproduce it and never when sending to pdf).
The reports may be designed by end users who are using my program.  I will not know what reports they are or if they have even put in parameters.  I will not know if they are date, string, number, discrete, range, multiple, etc.
The original login code referred to below can be found here.
         'original login code here down to subreport login
         'rest of subroutine is just a Catch and End Try
         crViewer.ReportSource = Nothing
         crViewer.ReportSource = crReport
         'check if to be sent direct to printer and send all pages
         If Not autoforms Is Nothing AndAlso autoforms.ToPrinter Then
            crReport.PrintOptions.PrinterName = autoforms.Printer
            crReport.PrintToPrinter(1, True, 0, 0)   '-> Error Triggers Here
         End If
         'setup viewer options
         Dim intExportFormatFlags As Integer
         intExportFormatFlags = ViewerExportFormats.PdfFormat Or
                                 ViewerExportFormats.ExcelFormat Or
                                 ViewerExportFormats.ExcelRecordFormat Or
                                 ViewerExportFormats.XLSXFormat Or
                                 ViewerExportFormats.CsvFormat
         crViewer.AllowedExportFormats = intExportFormatFlags
         crViewer.ShowLogo = False
         crViewer.ToolPanelView = ToolPanelViewType.GroupTree
         'check if to be sent direct to pdf and send all pages
         If Not autoforms Is Nothing AndAlso autoforms.ToPDF Then
            Dim strPDFFilename As String = autoforms.PDFPath & "\" & autoforms.ReportName & "_" & autoforms.ReportType & ".pdf"
            'strPDFFilename = Replace(strPDFFilename, " ", "_")
            SendExport(strPDFFilename, "PDF")
         End If
         'if not preview then close form
         If Not autoforms Is Nothing AndAlso Not autoforms.Preview Then
            Me.Close()
            Exit Sub
         End If
Private Sub SendExport(ByVal strFile As String, ByVal strExportFormat As String)
      'pass current parameter values to the pdf
      Dim crParamFieldDefs As ParameterFieldDefinitions
      Dim crParamFieldDef As ParameterFieldDefinition
      Dim crParamValues As New ParameterValues
      Dim x As Integer = crViewer.ParameterFieldInfo.Count
      crParamFieldDefs = crReport.DataDefinition.ParameterFields
      'loop through each parameter and assign it the current values
      For Each crParamFieldDef In crParamFieldDefs
         crParamValues = crParamFieldDef.CurrentValues
         crParamFieldDef.ApplyCurrentValues(crParamValues)
      Next
      Select Case strExportFormat
         Case Is = "PDF"
            crReport.ExportToDisk(ExportFormatType.PortableDocFormat, strFile)  '--> Error Triggers Here
         Case Is = "xls"
            crReport.ExportToDisk(ExportFormatType.Excel, strFile)
         Case Is = "xlsx"
            crReport.ExportToDisk(ExportFormatType.ExcelWorkbook, strFile)
      End Select
End Sub
This code doesn't work on my system, but my logic is as follows (as flawed as it is).  Look through the parameters, find the current values and then assign them to the parameters again just before export.
With the code above, I am getting the enter parameter values screen in the viewer.  Therefore, my assumption is that the report now has a current value(s) for the parameter(s).  The loop will not require the program to know how may parameters there are or what the values or value types are.
There are a couple of problems with this.  When I step through it, there are no current values, because the prompt doesn't come up with stepping through the code with F8.  Second problem is that it is finding the internal parameters used for subreport linking ({?PM-xxxxx}).  Third problem is that a lot of code I have looked at does not appear like it is assigning the reportsource to a viewer at all just to export or print to printer.  So is it necessary to do as I have done here?
I am sorry this is so long and I appreciate anyone who has stuck to it this long.  I am at my wits end trying to figure out how to make this work.  I think there is a timing issue here but do not know how to resolve it.  I just want the report to trigger the prompts if there are parameters, then send the report screen, to pdf or to printer depending on the user's settings for the report (it may be any or all three options).  If you need more info, let me know.
TIA, rasinc

Answer 1

Hi
I'd like to look at this from the "how parameters" work point of view. Then let's see if we can drill in on some of the details.
The parameter prompt screen is driven by the viewer. E,g.; the screen will only be spawned on invocation of the viewer. If the viewer is not invoked (e.g.; direct print / export) the parameter prompt screen will not be displayed. Now, in your second post you say:
With the code above, I am getting the enter parameter values screen in the viewer.
This does not sound correct based on the above. E.g.; if the correct parameters are passed to the engine, the viewer should never be popping up the parameter screen. So to me it looks like the code for the parameter is not actually working. It looks like it is as there is no error as such. But as you get prompted, the engine is essentially saying; "I don't understand those parameters so as smart as I am, I'll use the parameter prompt screen to get them from the user on a silver platter".
Ok. Now to some troubleshooting. I'd pick a report where I know the parameter type and acceptable values ahead of time. Don't use date or date / time params to start with as these have other complication. Use the parameter code to set the value(s) - preferably one value (I like to keep things simple). If the parameter is passed to the report engine correctly, there will not be a parameter prompt and the report will simply come up in the viewer. Once this works, add in a code for printing / exporting and comment out the viewer code. The report should print / export without any issues (no parameter prompt, no error). Repeat the above with a multi-parameter report.
Then it will come to those date and date/time parameters. NULL handling, etc., etc. E.g.; this will not be trivial. And you will somehow need to know the parameter type (string / int / date) before you try to pass it into the report. More help:
Sample apps
vbnet_win_paramengine.zip
vbnet_win_paramviewer.zip
vbnet_win_multirangeparam.zip
vbnet_win_rangeparameters.zip
vbnet_win_sub_daterange_param_engine.zip
vbnet_win_sub_daterange_param_viewer.zip
The above samples are here: Crystal Reports for .NET SDK Samples - Business Intelligence (BusinessObjects) - SCN Wiki
Helpful KBAs
1688710 - When printing a Crystal report with parameters using 'PrintToPrinter' method, report does not prompt for parameter values
1214110 - How to pass a Date/Time parameter to a report at runtime using VB .NET
1496220 - Suppress the default parameter prompt when the parameter value is not passed through the code
1893554 - How to pass a NULL value to a Crystal Reports optional parameter field using Visual Studio .NET
1425379 - How to avoid being prompted for a parameter when refreshing a report running in a VS .NET application
1461315 - Error; "Missing Parameter Values" when running a parameterized report using Crystal Reports SDK for VS .NET
1215426 - Err Msg: "Missing parameter value" when printing or exporting in VS .NET
And finally this:
Crystal Reports for Visual Studio 2005 Walkthroughs
(The above doc is good for all versions of CR and VS. It has some amazingly great "stuff" in it re. parameters, etc., and more.)
- Ludek
Senior Support Engineer AGS Product Support, Global Support Center Canada
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