java - 将 native 查询 JPA 的结果集设置为 POJO 抛出空指针异常

Question

我想将结果集List转换为实体类。我的 native 查询:

 @Query("select type,name,latitude,longitute,111.045* DEGREES (ACOS(COS(RADIANS(:latitude))*COS (RADIANS(latitude))*COS(RADIANS(:longitute) - RADIANS (longitute))"
            + "+SIN (RADIANS (:latitude))*SIN (RADIANS(latitude)))) As distance_in_km from Place ORDER BY distance_in_km ")
     List<Object[]> findBylattitudeAndlongitute(@Param("latitude") double latitude ,@Param("longitute") double longitute );

我的实体类:

@EnableCaching
@Entity
@Table(name = "PLACEDETAILS_H")
public class Place {

    public Place() {
    }   
    private String type;
    private String name;
    private String Code;
    private String Name;
    private String Code1;   
    private String Name2;
    private double latitude;
    private double longitute;

}

服务等级:

 List<Object[]>  places = Repository.findBylattitudeAndlongitute(latitude, longitute);  
Place place = null;
             for (Object[] pla:places)
             {
                 place.setType((String) pla[0]);
          place.setName((String) pla[1]);   
             }

由于 distance_in_km 不是变量实体，我无法直接映射结果集。查询执行成功，我正在获取响应列表。

我尝试将 pla[0] 设置为类型，但它显示空指针异常。帮我解决这个问题。

Answer 1

1. 您需要添加以下transient列:

   @Transient
   private Double distance_in_km;
   

2. 您需要将 Spring Data @Query 更改为 Hibernate native 查询:

   String sql = "select type as {p.type}, name as {p.name}, latitude as {p.latitude}, longitute as {p.longitute},111.045* DEGREES (ACOS(COS(RADIANS(:latitude))*COS (RADIANS(latitude))*COS(RADIANS(:longitute) - RADIANS (longitute))"
               + "+SIN (RADIANS (:latitude))*SIN (RADIANS(latitude)))) As {p.distanceInKm} from Place p ORDER BY {p.distanceInKm} ";
   
   List<Place> places = (List<Place>) session.createSQLQuery(sql)
   .setParameter("latitude", latitude)
   .setParameter("longitute", longitute)
   .addEntity("p", Place.class).list();