[英]HQL Left Join - org.hibernate.hql.internal.ast.ErrorCounter - Path expected for join
[英]Why I am obtaining this “ErrorCounter - Path expected for join!” trying to perform an HQL query that involves join between 2 tables?
我正在使用Spring Data JPA执行查询的Spring项目。
所以我有这两个实体类:
1)代表住宿房间的房间:
@Entity
@Table(name = "room")
public class Room implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Long id;
@ManyToOne
@JoinColumn(name = "id_accomodation_fk", nullable = false)
private Accomodation accomodation;
@ManyToOne
@JoinColumn(name = "id_room_tipology_fk", nullable = false)
private RoomTipology roomTipology;
@Column(name = "room_number")
private String number;
@Column(name = "room_name")
private String name;
@Column(name = "room_description")
@Type(type="text")
private String description;
@Column(name = "max_people")
private Integer maxPeople;
@Column(name = "is_enabled")
private Boolean isEnabled;
// CONSTRUCTOR, GETTER AND SETTER METHODS
}
如您所见,该类包含以下字段:
@ManyToOne
@JoinColumn(name = "id_room_tipology_fk", nullable = false)
private RoomTipology roomTipology;
将许多Room实例链接到RoomTipology实例。
2)然后我有RoomTipology实体类:
@Entity
@Table(name = "room_tipology")
public class RoomTipology implements Serializable{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Long id;
@Column(name = "tipology_name")
private String name;
@Column(name = "tipology_description")
private String description;
@Column(name = "time_stamp")
private Date timeStamp;
@OneToMany(mappedBy = "roomTipology")
private List<Room> rooms;
@OneToOne(mappedBy = "roomTipology")
private RoomRate roomRate;
// CONSTRUCTOR, GETTER AND SETTER METHODS
}
然后,我有了RoomTipology实体类的存储库分类,例如:
在其中,我想实现一个返回与特定房间ID相关的房间拓扑的方法。 所以我想实现此查询的HQL版本:
SELECT *
FROM `room_tipology` rt
INNER JOIN room r
ON rt.id = r.id_room_tipology_fk
WHERE r.id = 7
所以我有这种方式
@Repository
@Transactional(propagation = Propagation.MANDATORY)
public interface RoomTipologyDAO extends JpaRepository<RoomTipology, Long> {
@Query("from RoomTipology rt JOIN Room r ON rt.id = r.id_room_tipology_fk WHERE r.id = :roomId")
RoomTipology getInfoByRoomId(Long id);
}
问题是,执行我的申请时会收到以下错误消息:
[ERROR] 2016-12-03 11:47:41 [org.hibernate.hql.internal.ast.ErrorCounter.reportError(ErrorCounter.java:73)] [main] ErrorCounter - Path expected for join!
antlr.SemanticException: Path expected for join!
at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromJoinElement(HqlSqlWalker.java:385) [hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.joinElement(HqlSqlBaseWalker.java:3903) [hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3689) [hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3567) [hibernate-core-4.3.11.Final.jar:4.3.11.Final]
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Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: Path expected for join! [from com.betrivius.domain.RoomTipology rt JOIN Room r ON rt.id = r.id_room_tipology_fk WHERE r.id = :roomId]
at org.hibernate.hql.internal.ast.QuerySyntaxException.convert(QuerySyntaxException.java:91) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
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为什么? 怎么了? 我想念什么? 如何解决此问题?
您不需要JOIN ... ON,因为您已经在映射中定义了关系:
from RoomTipology rt JOIN rt.rooms r WHERE r.id = :roomId
https://docs.oracle.com/javaee/7/tutorial/persistence-querylanguage004.htm#BNBTL
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