JPA and Hibernate dosnt update one to many relation in first try in spring rest with JSON

Question

I have trying spring rest with hibernate, JPA and JSON. I have to entities like below:

University.java

@Entity()
@Table(name = "university")
public class University extends BaseEntity {
    private String uniName;

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
    @JoinColumn(name = "university_id", foreignKey = @ForeignKey(name = "university_id"))
    private Collection<Student> students;

    //setters and getters
}

Student.java

@Entity
@Table(name = "student")
public class Student extends BaseEntity {
    private String stuName;

    @ManyToOne(fetch = FetchType.EAGER)
    @JsonIgnoreProperties("students")
    private University university;

    //setters and getters
}

I have this dumy values in my db.

[
  {
    "id": 1,
    "uniName": "uni1",
    "students": [
      {
        "id": 1,
        "stutName": "st1",
        "university": {
          "id": 1,
          "uniName": "uni1"
        }
      },
      {
        "id": 2,
        "stutName": "st2",
        "university": {
          "id": 1,
          "uniName": "uni1"
        }
      }
    ]
  }
]

first try: When I try to update the university with its student, there is no success and this is my hibernate log

Hibernate:
    select
        university0_.id as id1_5_1_,
        university0_.uniName as uniName2_5_1_,
        students1_.university_id as universi3_4_3_,
        students1_.id as id1_4_3_,
        students1_.id as id1_4_0_,
        students1_.stuName as stuName2_4_0_,
        students1_.university_id as universi3_4_0_
    from
        university university0_
    left outer join
        student students1_
            on university0_.id=students1_.university_id
    where
        university0_.id=?
Hibernate:
    update
        student
    set
        stuName=?,
        university_id=?
    where
        id=?
Hibernate:
    update
        university
    set
        uniName=?
    where
        id=?
Hibernate:
    update
        student
    set
        stuName=?,
        university_id=?
    where
        id=?

second try: But when I Post same data for second time it is successful and the hibernate log is

Hibernate:
    select
        university0_.id as id1_5_1_,
        university0_.uniName as uniName2_5_1_,
        students1_.university_id as universi3_4_3_,
        students1_.id as id1_4_3_,
        students1_.id as id1_4_0_,
        students1_.stuName as stuName2_4_0_,
        students1_.university_id as universi3_4_0_
    from
        university university0_
    left outer join
        student students1_
            on university0_.id=students1_.university_id
    where
        university0_.id=?
Hibernate:
    select
        student0_.id as id1_4_0_,
        student0_.stuName as stuName2_4_0_,
        student0_.university_id as universi3_4_0_
    from
        student student0_
    where
        student0_.id=?
Hibernate:
    select
        student0_.id as id1_4_0_,
        student0_.stuName as stuName2_4_0_,
        student0_.university_id as universi3_4_0_
    from
        student student0_
    where
        student0_.id=?
Hibernate:
    update
        student
    set
        university_id=?
    where
        id=?
Hibernate:
    update
        student
    set
        university_id=?
    where
        id=?

Which is different from first one !!

What I am doing wrong in my hibernate annotations, or if I have missing something in my JSON annotation why the second try working.

UPDATE: this is my edit service.

@Override
@Transactional/*(propagation = Propagation.NESTED)*/
public T edit(T entity) throws Exception {
    return entityManager.merge(entity);
}

any help and advice is appreciated.

Answer 1

after changing my entities like below it worked perfectly.

University.java

@Entity()
@Table(name = "university")
public class University extends BaseEntity {
    private String uniName;

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
    @JoinColumn(name = "university_id")
    private Collection<Student> students;

    //setters and getters
}

Student.java

 @Entity
    @Table(name = "student")
    public class Student extends BaseEntity {
        private String stuName;

        @ManyToOne(fetch = FetchType.EAGER)
        @JoinColumn(name = "university_id",updatable = false,insertable = false)
        @JsonIgnoreProperties(value = "students", allowSetters = true)
        private University university;

        //setters and getters
    }

I hope this help someone else that have same issue.

Answer 2

Try to update your entities like so

@Entity
@Table(name = "university")
public class University extends BaseEntity {

    private String uniName;

    @OneToMany(mappedBy = "university", ...) // Check the mappedBy property
    private Collection<Student> students;

    //setters and getters

}

@Entity
@Table(name = "student")
public class Student extends BaseEntity {

    private String stuName;

    @ManyToOne(fetch = FetchType.EAGER)
    @JsonIgnoreProperties("students")
    private University university; // university is bidirectionally mapped to Student 

    //setters and getters
}