Question

我的域中有一个名为Activity的类，如下所示

@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="id")
@NodeEntity
public class Activity {

  @GraphId
  private Long id;

  private String title;

  private String description;

  @Relationship(type = "RELATED_TO", direction = Relationship.UNDIRECTED)
  private List<Activity> relatedActivities = new ArrayList<>();

  public Activity() {
  }

  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getTitle() {
    return title;
  }

  public String getDescription() {
    return description;
  }

  public Collection<Activity> getRelatedActivities() {
    System.out.println("getting relatedActivities");
    System.out.println(relatedActivities);
    return relatedActivities;
  }

  public void addRelatedActivity(Activity activity) {
    this.relatedActivities.add(activity);
  }
}

我使用以下存储库类创建关系：

@RepositoryRestResource(collectionResourceRel = "relationships", path = "relationships")
public interface RelationshipRepository extends GraphRepository<Relationship> {

  @Query("MATCH (a1:Activity), (a2:Activity) " +
  "WHERE a1.title = {0} AND a2.title = {1}" +
  "CREATE (a1)-[:RELATED_TO]->(a2)")
  void addRelationship(String a1Title, String a2Title);
}

我已经验证了此代码使用neo4j浏览器，它可以让我看到它们之间的现有节点和关系。但是，当我在Activity对象上访问getRelatedActivities（）时，它总是一个空数组，即使该Activity有与之相关的其他Activity节点，在neo4j中也清晰可见。

如何让Activity上的relatedActivites根据其关系自动填充？

Answer 1

您的代码中的问题是您定义了＆＃34; target＆＃34;在这里Activity

@Relationship(type = "RELATED_TO", direction = Relationship.UNDIRECTED)
private List<Activity> relatedActivities = new ArrayList<>();

但您的代码库中还有一个RelationshipEntity类：Relationship类型为RELATED_TO。

当OGM获得结果时，它会尝试匹配每个字段，但由于它将关系类型RELATED_TO转换为RelationshipEntity而不是Activity对象，因此它不会填充列表中的Activity班。

关系存在于neo4j中但不存在于Spring @NodeEntity中

1 个答案: