Nested lists

I want to design a report using subreports and nested lists using a scripted dataset. I am new to Birt and do not know if this is the correct approach.

The data looks like the following -
Parent : parentName, List<Children>
Children : childName, List<Hobbies>
Hobbies : title

I pass List<Parent> to the report and want to use subreports to fill in the hobbies per child. I created a datasource. When creating the dataset, how do I define the columns? i.e. easy to add a column for PARENT_NAME, but how do I define CHILDREN? Is it possible to use this type of data structure in BIRT?

Thanks!
Dee

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Comments

mwilliams

Hi Dee,

So you have parent, child, and hobby data sets? Can you explain more about your issue?

dee_jgd

Hi Michael 
 
I played around yesterday and found that using SubReports allows this. 
I am ignoring the hobbies for now and working on displaying parents and children. However, I am still not completely there. 
 
This is what I have coded in Master.rptdesign: 
 
Datasource and DataSet 
-Datasource: parentDS (scripted DS) 
 
-DataSet 1 : parentSet with output columns : PARENT_NAME, CHILDREN_SET of type ANY. 
 
-DataSet 2: childrenSet with output column : CHILD_NAME 
 
 DataSet 1 (parentSet) script for open and fetch 
- open script: 
gsh = new Packages.test.pojo.Parent(); 
parents = gsh.getReportList(); 
i = parents.iterator(); 
 
- fetch script: 
if (!i.hasNext()){ 
return false; 
} 
var parent = i.next(); 
row["PARENT_NAME"] = parent.getParentName(); 
row["CHILDREN_SET"] = parent.getChildren(); 
return true; 
 
 DataSet 2 (childrenSet) script for open and fetch 
- open script 
j=childrenSet.iterator(); 
 
In the Master design file, where I display the child name I use expression builder to define : 
childrenSet = row["CHILDREN_SET"]; 
row["CHILD_NAME"] 
 
- fetch 
if ( !j.hasNext() ){ 
return false ; 
} 
child = j.next(); 
row["CHILD_NAME"] = child.getName() ; 
return true ; 
 
 
I followed this example : <a class='bbc_url' href='http://dev.eclipse.org/newslists/news.eclipse.birt/msg03019.html'>[news.eclipse.birt] Re: Pojo's and a scripted subreport</a> 
 
When previewing, I get the an error. Can you advise on where I have gone wrong please? 
 
Unhandled exception when executing script 
Error.UnhandledScriptError ( 1 time(s) ) 
detail : org.eclipse.birt.report.engine.api.EngineException: Unhandled exception when executing script at org.eclipse.birt.report.engine.script.internal.ScriptExecutor.addException(ScriptExecutor.java:178) at org.eclipse.birt.report.engine.script.internal.ScriptExecutor.addException(ScriptExecutor.java:168) at org.eclipse.birt.report.engine.script.internal.ScriptDataSetScriptExecutor.handleFetch(ScriptDataSetScriptExecutor.java:119) at org.eclipse.birt.data.engine.impl.ScriptDataSetRuntime.fetch(ScriptDataSetRuntime.java:102) at org.eclipse.birt.data.engine.impl.PreparedScriptDSQuery$ScriptDSQueryExecutor$CustomDataSet.fetch(PreparedScriptDSQuery.java:257) at org.eclipse.birt.data.engine.executor.cache.OdiAdapter.fetch(OdiAdapter.java:150) at ...... 
(PoolTcpEndpoint.java:584) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683) at java.lang.Thread.run(Thread.java:619) 
Caused by: org.eclipse.birt.data.engine.core.DataException: data.engine.BadFetchScriptReturnType at org.eclipse.birt.report.engine.script.internal.ScriptDataSetScriptExecutor.handleFetch(ScriptDataSetScriptExecutor.java:109) ... 101 more

dee_jgd

The error is because of a line in the fetch statement:
row["CHILDREN_SET"] = parent.getChildren();

In the POJO, .getChildren returns a java.util.Set. I also tried a List but get same error. If I change the fetch to
row["CHILDREN_SET"] = parent.getParentName(); it works.
.getParentName returns a String. It seems to be an error in putting the Set into the CHILDREN_SET of type ANY.

Please help.