What is the best way to pass a dataset between two modules?  I thought about using IModuleCommunicator but that does not seem to be generic enough. I am trying to write a crystal reports module that will accept as input a dataset and a report name as input.

So when they press a button (or link etc.) the crystal report module will display, the crystal report will be loaded and use the dataset as its source.

thanks

Martin

I want to try and reeuse the reports module from other modules (with very different datasources). These other modules have datasets that the users filter to display on datagrids.  If I can just pass the dataset and the report name to the reports module and I would not have to go to the datasource (again) 

My (clumsy )solution was to create a global dataset that gets set by the calling module. The reports module then uses the global dataset to populate its dataset and loads the report (based on the Report Name parameter)

here is the code for the calling module:

 ======================================================
Private Sub cmdPrint_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdPrint.Click

   GlobalVars.DataDS = Me.DataDS
   Dim sReportName As String = Server.MapPath(".") & "\DesktopModules\Modules\ReportName.rpt"

   Dim params As String
   params = "ReturnURLKey=ViewListKey"

   Response.Redirect(EditUrl("ReportName", sReportName, "IPReport", params), True)

End Sub
======================================================

from the Report module:
======================================================
Private Sub LoadCrystalReport()

 'Load the dataset from the global dataset
 Dim ds As New DataSet
 ds = GlobalVars.DataDS

 Me.Report = New ReportDocument

 Dim sReportName As String = Me.ReportName
 If FileExists(sReportName) Then
   'Load the report
   Me.Report.Load(sReportName)

   'Set the dataset
   Me.Report.SetDataSource(ds)

               
   crvShowReport.ReportSource = Me.Report
   crvShowReport.Visible = True

 End If

End Sub
======================================================

I am sure there is a better way to this thats why I thought I'd ask here.

thanks

Martin

First thanks for your help and time.

I am sorry but I think my code snippet was confusing.  I was trying to illustrate how I am passing the dataset between modules.  However the dataset is not created until the user clicks on the print "link" or "button" I save the filter parameters in a string and use those to recreate the dataset when the user prints the report. I am with you on the pitfalls of keeping the dataset instantiated; I had done some testing and quickly realized that would not work.

You bring up an interesting point about the global variables. I don't think its actually global to all users but its something I should test. They are basically public vars in a "common" module so I thought the vars would be session dependent not global.

I would tend to agree that normally the best solution would be going to the datasource but I could save myself a lot of work if I could come up with a better solution.

Here is the situation. I have a page that displays data to the users (in a grid).  What is displayed varies because there are filters on the page (filter by user, type, date range, location, etc.) The user also determines how to sort the data.  I use dynamic SQL to create my DB query in a stored procedure. I also use business objects between my UI and database. My business object has a find "Find" procedure that calls my "Find" stored procedure through my data provider. BLL.Find(parameter1 as datatype, parameter2 as datatype, etc.) So I actually don't have the query that was used to create the dataset available to me otherwise I could simply pass the SQL string. Now I maybe forced to do that but I think it would create a lot of extra work for me (and have security issues as you pointed out)

What I want to do is generalize it so that I can pass a dataset to the module (or datatable it that works) and a report name. The report module would load the report name and use the dataset to populate it.  I could then use this for different pages.  In fact thats what I doing now.  I call my reports module from about 5 other modules.

These modules all have different objects with different filters and so far seems to work but more tests need to be done (I only generate the dataset when necessary) What I'd like to know is the best way to pass data (dataset and or datatable) between modules.  Now in my case  the number of rows is not that large (maybe 2K) records at most and this application is an intranet but i am still cognizant of the speed/size issue.

In any case thanks again for your insight I appreciate it.

Martin