Duplicate entry for key 'PRIMARY' in JPA/Hibernate
hibernate, jpa, many-to-many
Solution
I don't know if you managed to solve your problem yet, but I have just had exactly the same problem.
In my `@OneToMany` mapping I used `CascadeType.ALL` which resulted in 2 records being saved when I attempted to save the entity. (duplicated data, different ID's)
After scrolling on the web, I found this http://forums.codeguru.com/showthread.php?t=511992, so I changed from `CascadeType.ALL` to `{CascadeType.PERSIST, CascadeType.MERGE}`, which caused the error you have:
"ConstraintViolationException: Duplicate entry '9-2-2012-05-30' for key 'PlayerId'"
Finally I removed `CascadeType.MERGE` and was left with `CascadeType.PERSIST` which fixed the duplicate entry error and the duplicated records.
As a point, if I use just `CascadeType.MERGE` or just `CascadeType.PERSIST`, I get no errors and no duplicated data
Maybe try with `CascadeType.MERGE`and `CascadeType.PERSIST`, if you get errors, try with just `CascadeType.MERGE`.
It is not ideal, but hope it helps.
Chris
Problem
I have a `many-to-many` relation in a mysql database (`Module - <Module_has_Subject> - Subject`). Entites were generated by Eclipse, I added the method `add` in both classes. I use JBoss AS7/Hibernate. When I call the `persist` method in EJB, I get ``` org.hibernate.exception.ConstraintViolationException: Duplicate entry '3' for key 'PRIMARY' ``` I know it must be a trivial mistake, but I just don't see it. I went through most related problems here on StackOverflow and RoseIndia (I added `cascade`, `targetEntity`,...) and still without success. Entities for tables are as such: Module.java ``` @Entity @Table(name="Module") public class Module implements Serializable { @Id @Column(unique=true, nullable=false) private int idModule; //bi-directional many-to-many association to Subject @ManyToMany(mappedBy="modules", fetch=FetchType.EAGER,targetEntity=entity.Subject.class,cascade=CascadeType.ALL) private List<Subject> subjects; public void addSubject(Subject subject) { if(subject.getModules() == null) { subject.setModules(new ArrayList<Module>()); } if(getSubjects() == null) { setSubjects(new ArrayList<Subject>()); } if (!getSubjects().contains(subject)) { getSubjects().add(subject); } if (!subject.getModules().contains(this)) { subject.getModules().add(this); } } ...} ``` Subject.java ``` @Entity @Table(name="Subject") public class Subject implements Serializable { @Id @Column(unique=true, nullable=false) private int idSubject; //bi-directional many-to-many association to Module @ManyToMany(fetch=FetchType.EAGER, targetEntity=entity.Module.class,cascade=CascadeType.ALL) @JoinTable( name="Module_has_Subject" , joinColumns={ @JoinColumn(name="Subject_idSubject", nullable=false, referencedColumnName="idSubject") } , inverseJoinColumns={ @JoinColumn(name="Module_idModule", nullable=false, referencedColumnName="idModule") } ) private List<Module> modules; public void addModule(Module module) { if(getModules() == null) { setModules(new ArrayList<Module>()); } if(module.getSubjects() == null) { module.setSubjects(new ArrayList<Subject>()); } if (!getModules().contains(module)) { getModules().add(module); } if (!module.getSubjects().contains(this)) { module.getSubjects().add(this); } } ...} ``` SubjectEJB.java ``` ... Subject subject = new Subject(); for(Module module : subjectModules) { subject.addModule(module); } em.persist(subject); em.flush(); ... ```