I'm having an issue with serializing @RelationshipEntities to JSON via Spring Data Rest. Whenever I create the @RelationshipEntity, I run into an infinite recursion on serializing the graph to JSON.
Using JSOG to try to render the graph only results in a different, malformed JSON response.
While I can avoid the issue by using @JsonManagedReference, it doesn't solve the problem as I would like to expose the relationship from both nodes.
I've created a simple application that exhibits the issue. It can be found here: https://github.com/cyclomaniac/neo4j-spring-data-rest-cyclic
It implements very basic Team and Player NodeEntities with a single RelationshipEntity, PlayerPosition.
Player:
@NodeEntity
@JsonIdentityInfo(generator= JSOGGenerator.class)
public class Player {
@GraphId
@JsonProperty("id")
private Long id;
private String name;
private String number;
@Relationship(type = "PLAYS_ON")
private PlayerPosition position;
...
Team:
@NodeEntity
@JsonIdentityInfo(generator= JSOGGenerator.class)
public class Team {
@GraphId
@JsonProperty("id")
private Long id;
private String name;
@Relationship(type = "PLAYS_ON", direction = Relationship.INCOMING)
Set<PlayerPosition> teamPlayers;
...
PlayerPosition:
@RelationshipEntity(type="PLAYS_ON")
@JsonIdentityInfo(generator= JSOGGenerator.class)
public class PlayerPosition {
@GraphId
@JsonProperty("id")
private Long id;
private String position;
@StartNode
private Player player;
@EndNode
private Team team;
...
When wired up to a GraphRepository, hitting the /teams endpoint results in the following output with JSOG in place:
{
"_embedded" : {
"teams" : [ {
"@id" : "1",
"name" : "Cubs",
"teamPlayers" : [ {
"@id" : "2",
"position" : "Catcher",
"player" : {
"@id" : "3"
Notice that the JSON ends prematurely. The server throws an exception:
2016-11-04 15:48:03.495 WARN 12287 --- [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Failed to write HTTP message:
org.springframework.http.converter.HttpMessageNotWritableException:
Could not write content: Can not start an object,
expecting field name; nested exception is
com.fasterxml.jackson.core.JsonGenerationException:
Can not start an object, expecting field name
My assumption is that I've chosen a poor way to implement the relationship, though it feels fairly straightforward. I'd appreciate any tips on how I can properly expose this relationship, ideally via Spring Data Rest, from both the Team and Player nodes.
