Jasper sub-reports of sub-reports - programmatically - jasper-reports

Question

There are many examples of running sub-reports in Jasper on the web, but nobody seems to have had the problem that I have, when running a sub-report that contains another sub-report.
We store our report definitions in a Relational Database, and generate and run the reports out of a java service. We only use the GUI to design and test each report, to start with.
The reports are compiled and filled at runtime, and I can cause a sub-report to run, by using the well documented feature of adding the compiled sub-report to the main report at fill time using the report expression to use a sub-report as a parameter.
That is all fine. However, how can I fill the first sub-report with the compile output of the next sub-report down the tree?
To explain a little further, in JasperStudio, I can do this in the main report:
<subreport>
<reportElement x="4" y="100" width="547" height="310" uuid="f9364882-a530-475d-97af-8d6d2d47ae57"/>
<subreportParameter name="INSP_ID">
<subreportParameterExpression><![CDATA[$F{jobid}]]></subreportParameterExpression>
</subreportParameter>
<connectionExpression><![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
<subreportExpression><![CDATA["InspectionFrogSubReport.jasper"]]></subreportExpression>
</subreport>
Then in the first sub report, to refer to the next one, I can do this:
<subreport>
<reportElement x="280" y="56" width="270" height="294" uuid="b4cbe376-1b54-471c-a6d4-0d45afeab2c8"/>
<subreportParameter name="FROG_ID">
<subreportParameterExpression><![CDATA[$F{frog_id}]]></subreportParameterExpression>
</subreportParameter>
<connectionExpression><![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
<subreportExpression><![CDATA["InspectionDamageSubReport.jasper"]]></subreportExpression>
</subreport>
So, when I preview the mian, it fills the first sub, and then the next sub, no problem.
However, to fill from Java method, I change the main sub-report expression to:
<subreport>
<reportElement x="4" y="100" width="547" height="310" uuid="f9364882-a530-475d-97af-8d6d2d47ae57"/>
<subreportParameter name="INSP_ID">
<subreportParameterExpression><![CDATA[$F{jobid}]]></subreportParameterExpression>
</subreportParameter>
<connectionExpression><![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
<subreportExpression><![CDATA["$P!{SUB1}"]]></subreportExpression>
</subreport>
Then in my code:
// Compile sub report
InputStream childStream = new ByteArrayInputStream(subReport.getChildXml().getBytes());
JasperReport compiledChild = JasperCompileManager.compileReport(childStream);
// Compile Main report
InputStream xmlStream = new ByteArrayInputStream(report.getXml().getBytes());
JasperReport compiledReport = JasperCompileManager.compileReport(xmlStream);
// Build report parameter map
Map<String, Object> params = new HashMap<>();
params.put("SUB1", compiledChild);
// Fill main report
JasperPrint jasperPrint = JasperFillManager.fillReport(compiledReport, params, conn);
so far, so good. However, how do I pass the sub-sub-report into the sub-report. I cannot use 'fillReport' as the sub report will have no master record to work on until the main report runs.

Answer 1

Pass subSubReport as a param to supReport.
in java code:
params.put("SUB_SUB_REPORT", compiledSubSubreport);
in main report template xml:
<subreportParameter name="SUB_SUB_REPORT">
<subreportParameterExpression><![CDATA[$P{SUB_SUB_REPORT}]]></subreportParameterExpression>
</subreportParameter>
this is what you want?