Bonjour,

j'implémente JPA sur un projet pour gérer la persistance des données.
J'ai deux classes qui ont une association bidirectionnelle en 1..* des 2 côtés.
Je doit donc faire un ManyToMany pour sauvegarder dans la bdd. Mais je n'y arrive pas, j'ai nottament les erreurs suivantes :


Voici mes classes :

package projects;

import java.util.ArrayList;
import java.util.Collection;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;


@Entity
public class Project {
	
	private int id;
	private String name;
	private Collection<Group> group_list;
	
	//Constructors
	public Project()
	{
		group_list = new ArrayList<Group>();
	}
	
	public Project(String Pname)
	{
		group_list = new ArrayList<Group>();
		name = Pname;
	}

	//Getters and Setters
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	
	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	@OneToMany(mappedBy="project")
	public Collection<Group> getGroup_list() {
		return group_list;
	}
	
	public void setGroup_list(Collection<Group> group_list) {
		this.group_list = group_list;
	}
	
	//Methods
	public void addGroup(Group group)
	{
		group_list.add(group);
	}
}

package projects;

import java.util.ArrayList;
import java.util.Collection;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.JoinColumn;

@Entity
public class Group {
	
	private int id;
	private String name;
	private Project project;
	private Collection<Patient> patient_list;
	//Constructors
	
	public Group()
	{
		setName(new String(""));
		patient_list = new ArrayList<Patient>();
	}
	
	//Getters and Setters
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	
	public void setId(int id) {
		this.id = id;
	}	
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
    
    @JoinTable(
        name="Group_Patient",
        joinColumns=@JoinColumn(name="id_group"),
        inverseJoinColumns=@JoinColumn(name="id_patient")
    )
    @ManyToMany
	public Collection<Patient> getPatient() {
		return patient_list;
	}
	
	public void setPatient(Collection<Patient> patient) {
		this.patient_list = patient;
	}

	public Project getProject() {
		return project;
	}
	
	public void setProject(Project project) {
		this.project = project;
	}
	
	//Methods
	public void addPatient(Patient patient)
	{
		this.patient_list.add(patient);
	}
}

package projects;

import java.util.ArrayList;
import java.util.Collection;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;

@Entity
public class Patient {
	
	private int id;
	private String name;
	private Collection<Group> group_list;
	private String file_path;
	
	//Constructors
	
	public Patient()
	{
		setName(new String(""));
		setFile_path(new String(""));
		group_list = new ArrayList<Group>();
	}
	
	//Getters and Setters
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	
	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}

	@ManyToMany(mappedBy="patient_list")
	public Collection<Group> getGroup() {
		return group_list;
	}
	
	public void setGroup(Collection<Group> group) {
		this.group_list = group;
	}

	public String getFile_path() {
		return file_path;
	}
	
	public void setFile_path(String file_path) {
		this.file_path = file_path;
	}
	
	//Methods
	public void addGroup(Group group)
	{
		group_list.add(group);
	}
}

import java.util.Collection;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;

import projects.Group;
import projects.Patient;
import projects.Project;


public class testSQLiteMRIJ {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		EntityManagerFactory emf = Persistence.createEntityManagerFactory("mySql");
		
		EntityManager em = emf.createEntityManager();
		
		EntityTransaction tx = null;
		try {
			tx = em.getTransaction();
			tx.begin();
			
			Project p1 = new Project();
			p1.setName("Projet1");
			
			Group g1 = new Group();
			g1.setName("Groupe1");
			g1.setProject(p1);
			
			Group g2 = new Group();
			g2.setName("Groupe2");
			g2.setProject(p1);
			
			p1.addGroup(g1);
			p1.addGroup(g2);
			
			Patient patient1 = new Patient();
			patient1.setName("patient1");
			patient1.setFile_path("chemin du fichier");
			patient1.addGroup(g1);
			
			Patient patient2 = new Patient();
			patient2.setName("patient2");
			patient2.setFile_path("chemin du fichier...dj");
			patient2.addGroup(g1);
			patient2.addGroup(g2);
			
			g1.addPatient(patient1);
			g1.addPatient(patient2);
			g2.addPatient(patient2);
			
			em.persist(p1);
			em.persist(g1);
			em.persist(g2);
			em.persist(patient1);
			em.persist(patient2);
			
			tx.commit(); // do the flush automatically
						
		} catch (RuntimeException e) {
			if (tx != null && tx.isActive())
				tx.rollback();
			throw e; // or display error message
		} finally {
			em.close();
		}
		emf.close(); // close at application end
	}

}

Quelqu'un a-t-il déjà eu ce problème ?

Si tu veux utiliser ManyToMany tu dois rendre ton association uni-directionnelle. Une table d’association est donc nécessaire au niveau de la base de données
Bon courage.