Spring Data Neo4j implement relationship entity with @RelationshipProperties and @TargetNode

Question

I have the following legacy relationship entity which I'd like to upgrade to the latest SDN with @RelationshipProperties and @TargetNode:

@RelationshipEntity(type = "HAS_VALUE_ON")
public class RelationshipValue {

    @Id
    @GeneratedValue
    private Long graphId;

    @StartNode
    private Decision decision;

    @EndNode
    private Characteristic characteristic;

Could you please show how to implement it with @RelationshipProperties and @TargetNode annotations ?

Answer 1

A relationship with properties does not point towards both entities anymore but is a directed relationship. We do not make any assumptions if the TargetNode is an end or a start node. This is defined in the relationship-defining class.

Assuming that RelationshipValue is used in Decision and it should get connected to Characteristic, you would define something like:

@RelationshipProperties
public class RelationshipValue {

    @Id
    @GeneratedValue
    private Long graphId;

    @TargetNode
    private Characteristic characteristic;

and in Decision:

public class Decision {

    @Relationship("HAS_VALUE_ON") // direction can be OUTGOING (default) or INCOMING
    private RelationshipValue relationshipValue;
}

x-post: https://community.neo4j.com/t/spring-data-neo4j-implement-relationship-entity-with-relationshipproperties-and-targetnode/38429/2?u=gerrit.meier