Comment 1 for bug 1037481

First of all add '//' before the subreport field name. For example ((net.sf.jasperreports.engine.data.JRXmlDataSource)$P{REPORT_DATA_SOURCE}).subDataSource("//sub_report_field_name")')

Then check the datasource you have selected is xpath. Then in the python file there is a function called generate_datasource, which returns empty dict. Please change it to 'xml_records'