CODEWITHSUNDEEP
javaspringhibernate
Vlad
Vlad

Reputation: 99

Hibernate. Delete object

I have a relationship between Student entity and Publication as One to Many. I need to delete publication from sutdent. When I try to delete publication object but always get the exception:

org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [org.irs.entities.GroupStudent#1]

I do not know why it happens. I use Spring MVC 3.2 and Hibernate.

Student entity

@Entity
@org.hibernate.annotations.DynamicUpdate(value = true)
@Table(name = "Student")

public class Student implements Serializable {

public Student() {}

public Student(String studentFullName, String studentBook,
               int studentEnter, String studentOKR) {
    this.studentFullName = studentFullName;
    this.studentBook = studentBook;
    this.studentEnter =studentEnter;
    this.studentOKR = studentOKR;
}

// create connectivity with table GroupStudent
private GroupStudent groupStudent;

@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "GroupStudentId")
public GroupStudent getGroupStudent() {
    return this.groupStudent;
}

public void setGroupStudent(GroupStudent groupStudent) {
    this.groupStudent = groupStudent;
}

// create connectivity with table Publication
private Set<Publication> publications = new HashSet<Publication>();

@OneToMany(mappedBy = "student", cascade = CascadeType.ALL, orphanRemoval = true)
public Set<Publication> getPublications() {
    return publications;
}

public void setPublications(Set<Publication> publications) {
    this.publications = publications;
}
// other methods
}

Pulication entity

@Entity
@Table(name = "Publication")
public class Publication implements Serializable {
public Publication() {}

public Publication(String publicationTitle, String publicationType,
                   String publicationPlace, Date publicationDate) {

    this.publicationTitle = publicationTitle;
    this.publicationType = publicationType;
    this.publicationPlace = publicationPlace;
    this.publicationDate = publicationDate;
}

// create connectivity with table Student
private Student student;

@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "StudentId")
public Student getStudent() {
    return this.student;
}

public void setStudent(Student student) {
    this.student = student;
}

}

GroupStudent entity

@Entity
@Table(name = "GroupStudent")

public class GroupStudent implements Serializable {
public GroupStudent() {}

public GroupStudent(String groupStudentNumber) {
    this.groupStudentNumber = groupStudentNumber;
}

// create connectivity with table Student
private Set<Student> students = new HashSet<Student>();

@OneToMany(mappedBy = "groupStudent", cascade = CascadeType.ALL, orphanRemoval = true)
public Set<Student> getStudents() {
    return this.students;
}   

public void setStudents(Set<Student> students) {
    this.students = students;
}   
}

Controller

@RequestMapping(value = "/deletePublication.html", method = RequestMethod.GET)
public ModelAndView deletePublication(@RequestParam("studentId") Long studentId) {
....
ps.deletePublication(ps.selectPublicationsById(2L));
....
return modelandview;
}

Upvotes: 1

Views: 157

Answers (1)

Evgeni Dimitrov
Evgeni Dimitrov

Reputation: 22496

This error happens when you try to fetch entity that was already in the hibernate context. You can't have two attached entities at the same time. In your controller you firts call ps.selectPublicationsById(2L), that probably causes the error.

Try to replace the delete logicc with HQL or native SQL delete.

String hql = "delete from Publication where Id= :id";
session.createQuery(hql).setString("id", id).executeUpdate();

Upvotes: 1

Related Questions