How to alter JFreeChart Scriptlet example to use external data source?

[cbrownmacquarietelecom.co]

Hi,

 

I have used the JFreeChartScriptlet to generate a chart that uses the XYZDataset. For testing I've hardcoded the datasource (an XML file) but I need to hook the scriptlet up the report's datasource which is the content of a webservice response. Due to the number of data points it is impracticle to access the chart data via a number of fields.

 

The $V{Chart} is in a subreport; the subreport's data source expression is:

((net.sf.jasperreports.engine.data.JRXmlDataSource)$P{REPORT_DATA_SOURCE}).subDataSource("//data")[/code]

In the scriptlet I'm trying to access the data source as follows:

 

JRXmlDataSource xmlDataSource = (JRXmlDataSource) this.getParameterValue(JRFillParameter.REPORT_DATA_SOURCE);[/code]

When I preview the report I get the following exception:

net.sf.jasperreports.engine.JRException: net.sf.jasperreports.engine.fill.JRExpressionEvalException: Error evaluating expression for source text: ((net.sf.jasperreports.engine.data.JRXmlDataSource)$P{REPORT_DATA_SOURCE}).subDataSource("//data")

  at com.jaspersoft.studio.editor.preview.view.control.ReportControler.fillReport(ReportControler.java:524)

  at com.jaspersoft.studio.editor.preview.view.control.ReportControler.access$20(ReportControler.java:499)

  at com.jaspersoft.studio.editor.preview.view.control.ReportControler$5.run(ReportControler.java:380)

  at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

Caused by: net.sf.jasperreports.engine.fill.JRExpressionEvalException: Error evaluating expression for source text: ((net.sf.jasperreports.engine.data.JRXmlDataSource)$P{REPORT_DATA_SOURCE}).subDataSource("//data")

  at net.sf.jasperreports.engine.fill.JREvaluator.evaluate(JREvaluator.java:291)

  at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:618)

  at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:586)

  at net.sf.jasperreports.engine.fill.JRFillElement.evaluateExpression(JRFillElement.java:1020)

  at net.sf.jasperreports.engine.fill.JRFillSubreport.evaluateSubreport(JRFillSubreport.java:460)

  at net.sf.jasperreports.engine.fill.JRFillSubreport.evaluate(JRFillSubreport.java:351)

  at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:281)

  at net.sf.jasperreports.engine.fill.JRFillBand.evaluate(JRFillBand.java:504)

  at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(JRVerticalFiller.java:2026)

  at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(JRVerticalFiller.java:752)

  at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:259)

  at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:119)

  at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:558)

  at net.sf.jasperreports.engine.fill.BaseFillHandle$ReportFill.run(BaseFillHandle.java:119)

  at java.lang.Thread.run(Thread.java:745)

Caused by: org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'net.sf.jasperreports.engine.JREmptyDataSource@38c38f20' with class 'net.sf.jasperreports.engine.JREmptyDataSource' to class 'net.sf.jasperreports.engine.data.JRXmlDataSource'

  at org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToType(DefaultTypeTransformation.java:360)

  at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.castToType(ScriptBytecodeAdapter.java:599)

  at JFreeChartReport_1457576688536_715654.evaluate(calculator_JFreeChartReport_1457576688536_715654:304)

  at net.sf.jasperreports.engine.fill.JREvaluator.evaluate(JREvaluator.java:277)

  ... 14 more

 

 

How do I reference an external data source from within a scriptlet?

[ibad.rahman]

I am getting the exact same error, as far as I can tell. I don't know if scriptlets are involved though. I have some reports that work fine in iReports but produce errors in JasperSoft Studio. Hope someone can help with this issue.

[cbrownmacquarietelecom.co]

Hi,

I managed to get my report working eventually (using the settings given in my original query).

I have a report book component for which the data source expression uses net.sf.jasperreports.engine.JREmptyDataSource; I think my scriptlet erroneously referenced this data source (hence the error "Cannot cast object 'net.sf.jasperreports.engine.JREmptyDataSource ..."). 

To fix this I introduced an intermediate sub-report in which I defined the data source I needed to use in the scriptlet, then, eventually, called a sub-report with the appropriate Scriplet class set.

I hope this is useful.

Cheers

Chris