Neo4j spring - 在相同类型的实体之间创建双向关系

Question

我们想要的关系类型如下创建 (jack:Person {name:"Jack"})-[:KNOWS]->(jill:Person {name:"Jill"}) 与杰克，吉尔创建（杰克）<-[：知道]-（吉尔）；

下面我们如何建模？

@Node
public class User {

    @Id
    @GeneratedValue
    private UUID id;

    private String name;

    private String phoneNumber;

    private String email;

    private boolean isActive;

    @JsonIgnore
    @Relationship(type = "Knows", direction = Relationship.Direction.OUTGOING)
    private Set<Knows> knows;

    @JsonIgnore
    @Relationship(type = "Knows", direction = Relationship.Direction.INCOMING)
    private Set<Knows> knownBy;  

    public User() {
    }

    public void knows(Knows to) {
        if (knows == null) {
            knows = new HashSet<>();
        }
        knows.add(to);
    }

    public void knownBy(Knows from) {
        if (knownBy == null) {
            knownBy = new HashSet<>();
        }
        knownBy.add(from);
    }
 }

@RelationshipProperties
public class Knows {

    private String as;

    @CreatedDate
    private Instant createdAt;

    @JsonIgnore
    @TargetNode
    private User User;
}

保存用户的代码片段

      User user1 = userRepository.findById(id1);
      User user2 = userRepository.findById(id2);
      Knows knows = new Knows("as", Instant.now(), user1);
            Knows knownBy = new Knows("as", Instant.now(), user2);
            user2.knows(knows);
            user1.knownBy(knownBy);
            userRepository.save(user2);

有了这个，我们在保存用户实体的同时得到了 Whosebug。我们想知道这是正确的建模方法还是有更好的方法？

Answer 1

首先要注意的是：在将双向关系映射到数据库时，SDN 中存在一个错误。要跟踪的票是 https://jira.spring.io/browse/DATAGRAPH-1469 下个版本就很确定了

给你场景我会建议清理关系并只创建 OUTGOING 关系，如

@Node
public class User {
  // ... id etc.
  @Relationship("KNOWS")
  private List<Knows> knows;
}

在设置值时，两边都需要填充：

user1.knows(user2);
user2.knows(user1);

鉴于该错误在 SDN 6.0.3 发布之前一直存在，我建议要么单向工作，只连接一个方向的 Users 或 link Users直接。因此，您将无权访问关系中的属性。

@Node
public class User {
  // ... id etc.
  @Relationship("KNOWS")
  private List<User> knows;
}

Neo4j spring - 在相同类型的实体之间创建双向关系

Neo4j spring - Create a 2 way relationship between same type of entities

neo4j

spring-data-neo4j