Passing Parameters to Sub Reports in RDLC Under VS 2010 - asp.net

Question

Currently I'm working on a reporting website in VS 2010 using ASP.Net 4.0 and the 2010 RDLC designer. The report I'm building is similar to a Master-detail report, but I'm trying to do it with nested tables.
My issue is that I'm trying to pass a field value from my main report to a sub report. The table setup looks something like this:
2 Tables
First Table: [RecordID, Name, Date,]
Second Table: [RecordID, Description, DueDate]
What I want to do is a table like this:
-------------------
| Name | Date |
------------------------------------
| Description1 | DueDate |
------------------------------------
| Description2 | DueDate |
------------------------------------
| Name2 | Date2 |
-----------------
With the entries for Description and DueDate bieng part of the sub report.
When I try to pass the RecordID in to the subreport as a parameter, which I have to manually define in the XML of the subreport because I can't find anywhere in the designer UI that will allow me to add report parameters to RDLC files, I get an error from the main report that says:
An error occurred during local report processing.
Value cannot be null. Parameter name: value
So it appears to be erroring out before it ever reaches the point where it does the subreport loading.
I am getting data sent to the main report just fine, and if I remove the parameter from the subreport the data comes through. But if I add the parameter the report throws the error.
Does anyone have any ideas on what might be causing this?

Answer 1

I actually ended up figuring this out.
If you're using Visual Studio 2010 you need to go into the report definition file and make sure the Report Data window is open.
If you can't find it go to View and click on Report Data.
Once you have the window open right click on the Parameters folder and add the parameter there.
In the parameter declaration box make sure you select Allow Null Value and Allow Blank Value if it's a Text type. This should stop that error from happening.
For some reason, even though I always had a value, with local reporting it initializes the report parameter with null causing it to throw that error if you do not allow nulls/blanks.

Answer 2

Nobody seems to understand that the sub-report data needs to be shown /filtered based on the main report column values. Sorry for complaining but after spending quite a time, I figured this out.
We need to define report parameters as mentioned above in the subreport, we need to pass the parameter values to the datasource used by sub-report to display the subreport data. Given below is the snippet.. I have used ObjectDataSource to populate the subreport.
Public Sub SubreportProcessingEventHandler(ByVal sender As Object, ByVal e As SubreportProcessingEventArgs)
'e.Parameters.Item(0) is the report parameter defined in Sub-report
ObjectDataSource2.SelectParameters("Param1") = New Parameter("Param1", DbType.Int32, e.Parameters.Item(0).Values(0))
ObjectDataSource2.SelectParameters("Param2") = New Parameter("Param2", DbType.String, e.Parameters.Item(1).Values(0))
e.DataSources.Add(New ReportDataSource("SubReportDataSourceName", ObjectDataSource2))
End Sub

Answer 3

I just ran into same thing converting a report from VS2005. Anyhow, another thing I found was that the parameter had to be set in TWO places...
First, in the sub-report version, you have to declare the parameter(s) you are EXPECTING to receive coming in and its respective type.
In addition, from the MAIN report, if you right-click to the sub report, properties, there is a section for the "Parameters" that you want to pass TO the sub report. This would be from whatever record basis in the master report that will drive the sub report.
Just wanted to pass this on as clarification to others who may encounter or just be learning about handling sub reports in VS2010.