Hi all Hi all Thanks in advance for the attention and any suggestions. I hope my explanation of the issue is clear enough.
As noted in the subject line, I'm upgrading my java based project to Version 3 of the embedded API. Unfortunately, I'm getting the following error: SEVERE: exception in hasNext: The statement has been closed. Code is below, but here's the explanation. In order to provide a layer of isolation in between my application code and the database code (in this case Neo4j), I'm using the DAO pattern. I'm assigning the ResourceIterator I'm getting back from the findNodes call to a variable in the user level iterator I'm defining. According to this page (https://neo4j.com/docs/java-reference/current/javadocs/org/neo4j/graphdb/Transaction.html) "All ResourceIterables <https://neo4j.com/docs/java-reference/current/javadocs/org/neo4j/graphdb/ResourceIterable.html> that where returned from operations executed inside a transaction will be automatically closed when the transaction is committed or rolled back. Note however, that the ResourceIterator <https://neo4j.com/docs/java-reference/current/javadocs/org/neo4j/graphdb/ResourceIterator.html> should be closed <https://neo4j.com/docs/java-reference/current/javadocs/org/neo4j/graphdb/ResourceIterator.html#close--> as soon as possible if you don't intend to exhaust the iterator" That's clear enough and seems to explain why I am getting the exception. But there has to be some way to return an iterator for later use. At least I hope so. The other choice that comes to mind would be to store all of the nodes in user memory so my user level interface can iterate through them, and that would be a bit problematic. I'll note that this code (which used to use the GlobalGraphOperations class) worked in Neo4j 2. but maybe that was a bug in Neo4j 2? Note that I have tried not closing the transaction (or even using a transaction at all). Any ideas? Here's the actual source of the problem: It's in my definition of an iterator for the user visible structure representing nodes. public boolean hasNext() { // Wrap the neo4j iterator boolean hasN = false; GraphDatabaseService theDB = Neo4jDAOFactory.getTheNetworkDB(); Transaction tx = theDB.beginTx(); try { hasN = nodeIterator.hasNext(); } catch (Exception e) { // should send this back using the message logs eventually this.logger.log (Level.SEVERE, "exception in hasNext: " + e.getMessage(), e); } finally { tx.close(); } return hasN; } But it doesn't make sense without also looking at: public Iterator<NetworkNodeTransferObject> getNetworkNodes(String nameSpace, String key, Object value){ Neo4jNetworkNodeDAOIterator theIterator = null; GraphDatabaseService theDB = Neo4jDAOFactory.getTheNetworkDB(); Transaction tx = theDB.beginTx(); try { Label newLabel = Label.label(nameSpace); Iterator<Node> neo4jNodeList = theDB.findNodes(newLabel, key, value); theIterator = new Neo4jNetworkNodeDAOIterator(); theIterator.nodeIterator = neo4jNodeList; } catch (Exception e) { // should send this back using the message logs eventually this.logger.log (Level.SEVERE, "exception in getNetworkNodes: " + e.getMessage(), e); } finally { tx.close(); } return theIterator; } Thanks Howard -- You received this message because you are subscribed to the Google Groups "Neo4j" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
