Hi all,
I encountered a problem with the new TraversalDescription API in
1.1-SNAPSHOT (1.1-20100628.145423-131), using neo4j-commons-1.0.
The code
TraversalDescription descr = TraversalFactory.createTraversalDescription()
.breadthFirst()
.expand(TraversalFactory.expanderForType(RelTypes.HAS_CHILD,
Direction.OUTGOING))
.filter(getPredicateForTest(nodeTest))
;
throws
java.lang.InstantiationError: org.neo4j.commons.iterator.FilteringIterator
at
org.neo4j.kernel.StandardExpander$RegularExpander.doExpand(StandardExpander.java:523)
at
org.neo4j.kernel.StandardExpander$RelationsipExpansion.iterator(StandardExpander.java:145)
at
org.neo4j.kernel.impl.traversal.ExpansionSourceImpl.expandRelationships(ExpansionSourceImpl.java:54)
at
org.neo4j.kernel.impl.traversal.StartNodeExpansionSource.next(StartNodeExpansionSource.java:24)
at
org.neo4j.kernel.PreorderBreadthFirstSelector.nextPosition(PreorderBreadthFirstSelector.java:29)
at
org.neo4j.kernel.impl.traversal.TraverserImpl$TraverserIterator.fetchNextOrNull(TraverserImpl.java:139)
at
org.neo4j.kernel.impl.traversal.TraverserImpl$TraverserIterator.fetchNextOrNull(TraverserImpl.java:75)
at
org.neo4j.commons.iterator.PrefetchingIterator.hasNext(PrefetchingIterator.java:36)
at
org.neo4j.commons.iterator.IteratorWrapper.hasNext(IteratorWrapper.java:23)
on me when trying to iterate over the resulting Iterable<Node>, however
with a simple inline implementation of the RelationshipExpander
TraversalDescription descr = TraversalFactory.createTraversalDescription()
.breadthFirst()
.expand(new RelationshipExpander()
{
public Iterable<Relationship> expand(Node node)
{
return(node.getRelationships(RelTypes.HAS_CHILD,
Direction.OUTGOING));
}
public RelationshipExpander reversed()
{
return(null);
}
}
)
.filter(getPredicateForTest(nodeTest))
;
it works. Maybe this is a problem with
TraversalFactory.expanderForTypes(RelationshipType t, Direction d), but
I can't figure it out.. Am I missing something here? What is the best
practice to create such a TraversalDescription?
I also tried
TraversalDescription descr = TraversalFactory.createTraversalDescription()
.breadthFirst()
.relationships(RelTypes.HAS_CHILD, Direction.OUTGOING)
.filter(getPredicateForTest(nodeTest))
;
but got the same InstantiationError.
Thanks,
Christian
_______________________________________________
Neo4j mailing list
[email protected]
https://lists.neo4j.org/mailman/listinfo/user
