Active Reports - Single report with multiple subreport

I have created a single Active Report with a single subreport before. Not too difficult. Mine looked like this in the code view:

//create an xml datasource for the subreport
DataDynamics.ActiveReports.DataSources.XMLDataSource xmlDS = new DataDynamics.ActiveReports.DataSources.XMLDataSource();

//load data
XmlDocument xDoc = new XmlDocument();
xDoc.LoadXml(booksXml.ToString());
xmlDS.FileURL = null;
xmlDS.RecordsetPattern = "//book";
xmlDS.LoadXML(xDoc.InnerXml);

//set report datasource
BookDetail ed = new BookDetail();
this.subReport1.Report = ed;
this.subReport1.Report.DataSource = xmlDS;

Okay, so I thought when I added a second subreport with different data, I could just do the same, but I added an if statement that skipped doing anything with the subreport if the object was null.

And, THAT was a problem, it seems. When I would run the report, nothing showed up in the second subreport, even though it should have. Even when I put a breakpoint in the subreport, the Fetch method wasn't being hit - that was a clue.

Well, I guess, even if you have null data you still gotta do something with the subsequent subreport. So, I found an example on the AR support site that explained this to me - setting up a dummy object.

//create an xml datasource for the subreport
DataDynamics.ActiveReports.DataSources.XMLDataSource finalDS = new DataDynamics.ActiveReports.DataSources.XMLDataSource();

XElement BookXml = new XElement("Books");
BookXml.Add(Book.ToXml());

//load data
XmlDocument doc = new XmlDocument();
doc.LoadXml(booksXml.ToString());
finalDS.FileURL = null;
finalDS.RecordsetPattern = "//book";
finalDS.LoadXML(doc.InnerXml);


User_Book book = Book.GetItem(b.ID, m.ID);

if book != null)
{
//set subreport datasource
BookDetail fed = new BookDetail();
this.subReport2.Report = fed;
this.subReport2.Report.DataSource = finalDS;
}
else
{
BookDetail fed = new BookDetail();
fed.DetailData = false;
this.subReport2.Report = fed;
}

Hope this helps someone!