CODEWITHSUNDEEP
javasql-serverspringhibernate
N.A
N.A

Reputation: 855

Hibernate Joins In Spring boot application

I am using Spring boot MVC application with hibernate ORM.

I have a table as student which has foreign keys from other tables.

Student.java:

@Entity
@Table(name = "STUDENT")

public class student{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long STUDENT_ID;   

@OneToOne
@JoinColumn(name="COURSE_ID")
private Long COURSE_ID;

@OneToOne
@JoinColumn(name="ACDYEAR_ID")
private Long ACDYEAR_ID; 

@OneToOne
@JoinColumn(name = "SEMESTER_ID")
private Long SEMESTER_ID;
}

StudentRepository:

@Query(value="SELECT * FROM STUDENT INNER JOIN ACADEMICSYEAR ON      STUDENT.ACDYEAR_ID = ACADEMICSYEAR.ACDYEAR_ID  INNER JOIN ACADEMICSCOURSE ON STUDENT.COURSE_ID = ACADEMICSCOURSE.COURSE_ID where STUDENT_ID=?1",
        nativeQuery=true)
 public STUDENT findOneID(Long id);

Same query in sql server returns populated academic year table and course table but here it is giving an error like

   org.hibernate.AnnotationException: @OneToOne or @ManyToOne on com.boot.model.STUDENT.COURSE_ID references an unknown entity: java.lang.Long

Upvotes: 0

Views: 1132

Answers (2)

SparkOn
SparkOn

Reputation: 8956

Instead of having type of the id of the entity in the association, have the type of the entity. Example

@Entity
@Table(name = "STUDENT")

public class student{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long STUDENT_ID;   

@OneToOne
@JoinColumn(name="COURSE_ID")
private Course course;
}

Where Course is the associated entity in the unidirectional relationship

Upvotes: 0

oak
oak

Reputation: 3028

Hey there,

The reason it does not work its because you are trying to map Long object as entity ( because of OneToOne,ManyToOne mapping). you should map each field to another entity instead of mapping it to Long. Or, just fetch the ids

Two solutions:

First option - fetch ids only

remove all @OneToOne annotation and JoinColumn

@Column(name="COURSE_ID")
private Long COURSE_ID;

@Column(name="ACDYEAR_ID")
private Long ACDYEAR_ID; 


@Column(name = "SEMESTER_ID")
private Long SEMESTER_ID;

Second option

Create an entity for each table i.e Course entity, Semester entity and ACADEMICSYEAR entityand change theLong in each place to be that entity

Upvotes: 2

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