[JENA-52] GROUP_CONCAT DISTINCT on unbound variable causes NPE

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Done
• Fix Version/s: Jena 2.11.0
• Component/s: ARQ
• Labels: arq group_concat npe

Environment

Java

• Assignee: Andy Seaborne
• Reporter: Damian Steer
• Created: 28/Feb/11 17:37
• Updated: 01/Feb/15 19:11
• Resolved: 01/Feb/15 19:11

Description

Data:

@prefix ex: <http://example.com/ns#> .
ex:a ex:p1 "1" .
ex:b ex:p1 "2" ; ex:p2 "3" .

Query:

prefix ex: <http://example.com/ns#>
select ?s (group_concat(distinct ?p2) as ?concat) 
{ ?s ex:p1 ?p1 optional { ?s ex:p2 ?p2 } }
group by ?s

Result:

java.lang.NullPointerException
	at com.hp.hpl.jena.sparql.expr.aggregate.AggGroupConcatDistinct$AccGroupConcatDistinct.getValue(AggGroupConcatDistinct.java:124)
	at com.hp.hpl.jena.sparql.expr.aggregate.AggregatorBase.getValue(AggregatorBase.java:62)
	at com.hp.hpl.jena.sparql.engine.iterator.QueryIterGroup$1.initializeIterator(QueryIterGroup.java:147)
	at org.openjena.atlas.iterator.IteratorDelayedInitialization.init(IteratorDelayedInitialization.java:25)