Question

我的SkillCluster课程如下

@ExceptionHandler({
    javax.validation.ConstraintViolationException.class,
    org.hibernate.exception.ConstraintViolationException.class,
    org.springframework.dao.DataIntegrityViolationException})

其对应的DAO类

public class SkillCluster {
    @Id @GeneratedValue
    private Long id;
    private String Name;
    private String CleanedText;

    @Relationship(type = "BelongsTo", direction = Relationship.INCOMING)
    private Set<Skill> contains = new HashSet<>();
}

和我的GenericDAO类为

import org.neo4j.ogm.session.Session;
import com.models.GenericDAO;

public class SkillClusterDAO extends GenericDAO<SkillCluster>{
    public SkillClusterDAO(Session session) {
        super(session);
    }

    protected Class<SkillCluster> getEntityType() {
        return SkillCluster.class;
    }   
}

我希望通过匹配Node属性public abstract class GenericDAO<T> { private static final int DEPTH_LIST = 0; private static final int DEPTH_ENTITY = 1; private Session session; public long filterCount(Iterable<Filter> filters){ return session.count(getEntityType(), filters); } public T find(Long id) { return session.load(getEntityType(), id, DEPTH_ENTITY); } public T find(String name) { return session.load(getEntityType(), name, DEPTH_ENTITY); } public void delete(Long id) { session.delete(session.load(getEntityType(), id)); } public void createOrUpdate(T entity) { session.save(entity, DEPTH_ENTITY); //return find(entity.id); } protected abstract Class<T> getEntityType(); public GenericDAO(Session session) { this.session = session; } }来获取群集节点

Name

我收到了以下错误 -

skillSessionFactory = new SessionFactory(skillConfiguration, "com.skill.models");
skillSession = skillSessionFactory.openSession();

skillClusterDAO = new SkillClusterDAO(skillSession);
SkillCluster clusterNode = skillClusterDAO.find(cluster_name);

Answer 1

您遇到此错误，因为name属性不是Long。

即使你的名字属性也是Long，它也行不通，因为它本来会被错误地取出。

session.load(...)适用于内部节点ID，或标记为@Id或主索引@Index(primary = true)的属性。

如果您需要通过其属性而不是主键来查找节点，则可以将session.loadAll(...)与过滤器一起使用。

public abstract class GenericDAO<T> {

  ...

  import java.util.Collection;
  import java.util.Optional;
  import org.neo4j.graphdb.GraphDatabaseService;
  import org.neo4j.ogm.cypher.Filter;
  ...

  public T find(Long id) {
    return session.load(getEntityType(), id, DEPTH_ENTITY);
  }

  public T find(String name) {
    final String propertyName = "name";
    Filter filter = new Filter(propertyName, name);

    Collection<T> results = session.loadAll(getEntityType(), filter, DEPTH_ENTITY);

    if( results.size() > 1)
      throw new CustomRuntimesException("Too results found");

    Optional<T> entity = results.stream().findFirst();

    return entity.isPresent() ? entity.get() : null;
 }

 ...

}

使用neo4j OGM按属性名称查找节点

1 个答案: