I am working on a Spring project using Spring Data JPA to perform query.
So I have these 2 entity classes:
1) Room representing a room of an accomodation:
@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
}
As you can see this class contains this field:
@ManyToOne
@JoinColumn(name = "id_room_tipology_fk", nullable = false)
private RoomTipology roomTipology;
that link many Room instance to a RoomTipology instance.
2) Then I have RoomTipology entity class:
@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
}
Then I have this repository clas for the RoomTipology entity class, something like:
in which I want implement a method that return the room tipology associated to a specific room id. So I want implement an HQL version of this query:
SELECT *
FROM `room_tipology` rt
INNER JOIN room r
ON rt.id = r.id_room_tipology_fk
WHERE r.id = 7
So I have donw in this way:
@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);
}
The problem is that performing my appliction I obtain this error message:
[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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Why? What is wrong? What am I missing? How can I fix this issue?
You don't need the JOIN ... ON because you have defined the relationship already in the mapping:
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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