Having trouble getting Entity's "child" loaded via #Query in Sprint Neo4j - neo4j

Question

I have an entity like this:
#NodeEntity
public class Move {
#Id #GeneratedValue private Long id;
#Property("placement")
private String placement;
#Relationship(type="PARENT", direction=Relationship.INCOMING)
BoardPosition parent;
#Relationship("CHILD")
BoardPosition child;
[...]
When I "load" it like this:
Move the_move = m_store.findByPlacement("C1");
log.info("Move direct load: " + the_move.toString());
it works fine. Both the parent and child properties have the correct value.
However, when I access it via a query defined like this:
public interface MoveStore extends Neo4jRepository<Move, Long> {
public Move findByPlacement(String placement);
#Query("MATCH (n:Move) RETURN n")
public List<Move> findAll();
and accessed like this:
ListIterator<Move> moves = m_store.findAll().listIterator();
while(moves.hasNext() ) {
log.info(moves.next().toString());
}
it is missing the child value (is null).
This experiment is strange:
while(moves.hasNext() ) {
Move m = moves.next();
log.info(m.toString()); // This is missing m.child's value
// find the same Move, by passing in the id of this one:
m = m_store.findById(m.id).orElse(null);
log.info(m.toString()); // This has the correct value for m.child!
}
What am I missing? How can I make the query load the child property?

Answer 1

When you are using the custom query, you have also to return the relationship and related nodes to get the child populated.
e.g. #Query("MATCH (n:Move)-[rel:CHILD]-(c:BoardPosition) RETURN n, rel, c") would do the job for a 1:1 relationship otherwise a collect(...) is needed to get the list in the same result "row" as the node you are querying for.