postgresql - PSQLException : The column name clazz_ was not found in this ResultSet

Question

我正在尝试获取 PlaceEntity。我之前存储了一堆 GooglePlaceEntity 对象，其中

@Entity
@Table(name = "place")
@Inheritance(
        strategy = InheritanceType.JOINED
)
public class PlaceEntity extends AbstractTimestampEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
}

和

@Entity
@Table(name = "google_place")
public class GooglePlaceEntity extends PlaceEntity {
    // Additional fields ..
}

---

但是，我既不想发送存储在 google_place 中的信息，也不想不必要地加载它。出于这个原因，我只是在获取

public interface PlaceRepository extends JpaRepository<PlaceEntity, Long> {

    @Query(value = "" +
            "SELECT * " +
            "FROM place " +
            "WHERE earth_distance( " +
            "   ll_to_earth(place.latitude, place.longitude), " +
            "   ll_to_earth(:latitude, :longitude) " + 
            ") < :radius",
            nativeQuery = true)
    List<PlaceEntity> findNearby(@Param("latitude") Float latitude,
                                 @Param("longitude") Float longitude,
                                 @Param("radius") Integer radius);

}

我得到的是这样的:

org.postgresql.util.PSQLException: The column name clazz_ was not found in this ResultSet.
    at org.postgresql.jdbc.PgResultSet.findColumn(PgResultSet.java:2588) ~[postgresql-9.4.1208-jdbc42-atlassian-hosted.jar:9.4.1208]
    at org.postgresql.jdbc.PgResultSet.getInt(PgResultSet.java:2481) ~[postgresql-9.4.1208-jdbc42-atlassian-hosted.jar:9.4.1208]
    at com.zaxxer.hikari.pool.HikariProxyResultSet.getInt(HikariProxyResultSet.java) ~[HikariCP-2.7.8.jar:na]
    at org.hibernate.type.descriptor.sql.IntegerTypeDescriptor$2.doExtract(IntegerTypeDescriptor.java:62) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
    at org.hibernate.type.descriptor.sql.BasicExtractor.extract(BasicExtractor.java:47) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
    ...

我可以在纯 PostgreSQL 中运行这条语句:

SELECT * FROM place WHERE 
earth_distance( 
  ll_to_earth(place.latitude, place.longitude), 
  ll_to_earth(17.2592522, 25.0632745)
) < 1500;

但不使用 JpaRepository。

顺便说一句，获取 GooglePlaceEntity 是有效的:

@Query(value = "" +
        "SELECT * " +
        "FROM place JOIN google_place ON google_place.id = place.id " +
        "WHERE earth_distance( " +
        "   ll_to_earth(place.latitude, place.longitude), " +
        "   ll_to_earth(:latitude, :longitude) " + 
        ") < :radius",
        nativeQuery = true)
List<GooglePlaceEntity> findNearby(@Param("latitude") Float latitude,
                                   @Param("longitude") Float longitude,
                                   @Param("radius") Integer radius);

Answer 1

在 @Inheritance(strategy = InheritanceType.JOINED) 的情况下，当您在 JPA 存储库 中检索没有 nativeQuery=True 的数据时，< strong>Hibernate 将执行如下 SQL:

SELECT
table0_.id as id1_1_,
table0_.column2 as column2_2_1_,
... (main_table cols)
table0_1_.column1 as column1_1_0_,
... (table1 to N-1 cols)
table0_N_.column1 as column1_1_9_,
... (tableN-th cols)
CASE WHEN table0_1_.id is not null then 1
    ... (table1 to N-1 cols)
    WHEN table0_N_.id is not null then N
    WHEN table0_.id is not null then 0
    END as clazz_
FROM table table0_
left outer join table1 table0_1_ on table0_.id=table0_1_.id
... (other tables join)
left outer join table2 table0_N_ on table0_.id=table0_N_.id

从上面的 SQL 可以看到 clazz 规范。如果您想将 ResultSet 映射到您的 super 实例(PlaceEntity)，您应该自己在 SELECT 中指定 clazz_ 列。

你的情况是:

@Query(value = "" +
            "SELECT *, 0 AS clazz_ " +
            "FROM place " +
            "WHERE earth_distance( " +
            "   ll_to_earth(place.latitude, place.longitude), " +
            "   ll_to_earth(:latitude, :longitude) " + 
            ") < :radius",
            nativeQuery = true)