Neo4J in Action (revised CustomFilteringEvaluator)

CustomFilteringEvaluator.java

import org.neo4j.graphdb.traversal.Evaluator;
import org.neo4j.graphdb.traversal.Evaluation;
import org.neo4j.graphdb.*;

// exclude Movies seen by userNode
public class CustomFilteringEvaluator implements Evaluator {
    private RelationshipType hasSeenRelationshipType = DynamicRelationshipType.withName("HAS_SEEN");
    private final Node userNode;
    public CustomFilteringEvaluator(Node userNode) {
	this.userNode = userNode;
    }
    private boolean seenByUserNode(Node movieNode) {
	for (Relationship r : movieNode.getRelationships(Direction.INCOMING, hasSeenRelationshipType)) {
	    if (r.getStartNode().equals(userNode))
		return true;
	}
	return false;
    }
    public Evaluation evaluate(Path path) {
	Node currentNode = path.endNode();
	if (!currentNode.hasProperty("type") || !currentNode.getProperty("type").equals("Movie") || seenByUserNode (currentNode))
	    return Evaluation.EXCLUDE_AND_CONTINUE;
	return Evaluation.INCLUDE_AND_CONTINUE;
    }
}