Duplicated rows on the database

[Luiz Abrahao]

Hi!

I'm confused and I think I'm missing some concept.

The sort version: The entity is persisted twice if I call childEntityDAO.makePersistent(e).

The long version: I have 2 entities, Company and Division.

import java.io.Serializable;
import java.util.Date;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

import org.hibernate.annotations.Cascade;
import org.jboss.seam.annotations.Name;

@Entity
@Table(name="COMPANY")
@EntityListeners(com.eukleia.model.entity.common.monitor.CompanyMonitor.class)
@Name("company")
public class Company implements Serializable {
   private static final long serialVersionUID = -7076265969258176592L;
   
   @Id @GeneratedValue
   @Column(name="COMPANY_ID")
   private Long id;
   
   @Column(name="COMPANY_NAME")
   private String name;
   
   @Column(name="COMPANY_FOLDER")
   private String folder;
   
   @Column(name="COMPANY_TRIAL")
   private boolean trial;
   
   @Temporal(TemporalType.DATE)
   @Column(name="COMPANY_EXPIRES")
   private Date expires;
   
   @OneToMany(mappedBy = "company", cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE})
   @Cascade(value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
   private Set<Division> divisions = new HashSet<Division>();
   
   public Company() {}

   public Company(String name){
      this.name = name;
   }
   
       // getters and setters

   public void addDivision(Division division) {
      division.setCompany(this);
      divisions.add(division);
   }
   
   public boolean hasExpired() {
      if (this.expires == null)
         return false;
      
      if (this.expires.before(new Date()))
         return true;
      
      return false;
   }
   
   @Override
   public int hashCode() {
      final int prime = 31;
      int result = 1;
      result = prime * result + ((folder == null) ? 0 : folder.hashCode());
      result = prime * result + ((id == null) ? 0 : id.hashCode());
      return result;
   }

   @Override
   public boolean equals(Object obj) {
      if (this == obj)
         return true;
      if (obj == null)
         return false;
      if (getClass() != obj.getClass())
         return false;
      Company other = (Company) obj;
      if (folder == null) {
         if (other.folder != null)
            return false;
      } else if (!folder.equals(other.folder))
         return false;
      if (id == null) {
         if (other.id != null)
            return false;
      } else if (!id.equals(other.id))
         return false;
      return true;
   }
}

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import org.hibernate.annotations.Cascade;
import org.jboss.seam.annotations.Name;

@Entity
@EntityListeners(com.eukleia.model.entity.common.monitor.DivisionMonitor.class)
@Table(name="DIVISION")
@Name("division")
public class Division implements Serializable{
   private static final long serialVersionUID = 4771732014913737248L;
   
   @Id @GeneratedValue
   @Column(name="DIVISION_ID")
   private Long id;
   
   @Column(name="DIVISION_NAME")
   private String name;
   
   @Column(name="DIVISION_FOLDER")
   private String folder;
   
   @Column(name="DIVISION_USERNAME")
   private String username;
   
   @Column(name="DIVISION_PASSWORD")
   private String password;   
   
   @ManyToOne(targetEntity = com.eukleia.model.entity.common.Company.class)
   @JoinColumn(name = "COMPANY_ID", nullable = false)
   private Company company;
   
   @OneToMany(mappedBy = "division", cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE})
   @Cascade(value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
   private Set<User> users = new HashSet<User>();
   
   @OneToMany(mappedBy = "division", cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE})
   @Cascade(value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
   private Set<Course> courses = new HashSet<Course>();
   
   public Division() {}
   
   public Division(String name) {
      this.name = name;
   }
   
   public Division(String name, Company company) {
      this.name = name;
      this.company = company;
   }
   
   public Division(String name, String folder, String username,
         String password, Company company) {

      this.name = name;
      this.folder = folder;
      this.username = username;
      this.password = password;
      this.company = company;
   }

   public Division(String name, String folder, String username, String password) {
      super();
      this.name = name;
      this.folder = folder;
      this.username = username;
      this.password = password;
   }

        // getters and setters

   public void addUser(User user) {
      user.setDivision(this);
      users.add(user);
   }
   
   public void addCourse(Course course) {
      course.setDivision(this);
      courses.add(course);
   }
   
   @Override
   public int hashCode() {
      final int prime = 31;
      int result = 1;
      result = prime * result + ((folder == null) ? 0 : folder.hashCode());
      result = prime * result + ((id == null) ? 0 : id.hashCode());
      return result;
   }

   @Override
   public boolean equals(Object obj) {
      if (this == obj)
         return true;
      if (obj == null)
         return false;
      if (getClass() != obj.getClass())
         return false;
      Division other = (Division) obj;
      if (folder == null) {
         if (other.folder != null)
            return false;
      } else if (!folder.equals(other.folder))
         return false;
      if (id == null) {
         if (other.id != null)
            return false;
      } else if (!id.equals(other.id))
         return false;
      return true;
   }
}

The DAO layers is implemented as described in the section 16.4.2 of Java Persistence with Hibernate. If I try to save a Division like the follow listing it works fine:

Company c = companyDAO.findById(new Long(2), true);
Division d = new Division("Division 999", "Division 999", "division.999", "password");
c.addDivision(d);
c = companyDAO.makePersistent(c);

But if I call the divisionDAO.makePersistent(d) I got 2 identical (apart form the ID column) rows on my database. I need to call the makePersistent method because I need to get the ID of the persisted entity to use on my tests.

I found out that there is a bug (http://opensource.atlassian.com/projects/hibernate/browse/HHH-3810) that affects the version of the hibernate I was using.

I updated to the 3.3.2 but it didn't stop the entity to be persisted twice.

As far as I understood from the book if I call the d = divisionDAO.makePersistent(d) should be ignored. There must be something wrong with my mapping then.

Any ideas appreciated,
Luiz Filipe

[Edwin Dalorzo]

Can it be related to the implementation of equals and hashcode?

https://www.hibernate.org/109.html

[Paul Sturrock]

Yeah, that's pretty whacky logic for equality you have there - if a Department has a Folder, use that to test equality, otherwise use the primary key. Why do you not just use the ID?

[Luiz Abrahao]

Thank you for your reply!

These entities were ported from hibernate to JPA, I only added the annotations though, both hashCode and equals methods were generated by eclipse. I have applications using these entities for quite long time, with no problems.

Edwin, I read the article you send, unfortunately I can't spot anything wrong with the entities' hasCode and equals.

I found something interesting, and I posted it here: https://forum.hibernate.org/viewtopic.php?f=1&t=1001405. I have the feeling that this problem is something related with the my tests structure.

Paul Sturrock wrote:Yeah, that's pretty whacky logic for equality you have there - if a Department has a Folder, use that to test equality, otherwise use the primary key. Why do you not just use the ID?

Sorry Paul, I don't know if I understood well, because either folder and id are already being used to test equality.

Again, thank you for your time
Luiz Filipe

[Paul Sturrock]

Sorry Paul, I don't know if I understood well, because either folder and id are already being used to test equality.

So, do you really have a composite key here? Remember a primary key cannot be null, and equality in a database application is done by primary key. If you have a nullable field in there there is something wrong with your data modelling.