diff --git a/src/main/java/fr/istic/taa/jaxrs/DAO/QuestionDAO.java b/src/main/java/fr/istic/taa/jaxrs/DAO/QuestionDAO.java
index 7fac75a..7053d0c 100644
--- a/src/main/java/fr/istic/taa/jaxrs/DAO/QuestionDAO.java
+++ b/src/main/java/fr/istic/taa/jaxrs/DAO/QuestionDAO.java
@@ -12,71 +12,97 @@ import fr.istic.taa.jaxrs.metier.Utilisateur;
 import jakarta.persistence.EntityTransaction;
 
 public class QuestionDAO extends AbstractJpaDao<Integer, Question> {
-    public QuestionDAO(){
+    public QuestionDAO() {
         super();
         this.setClass(Question.class);
     }
 
-
-    public void addReponse(String reponse, int questionId){
+    public void addReponse(String reponse, int questionId) {
         EntityTransaction t = em.getTransaction();
-        t.begin();
-        Question q = em.find(Question.class,questionId);
-
-        q.getReponse().getReponses().add(reponse);
-        em.merge(q);
-        t.commit();
+        try {
+            if (!t.isActive()) t.begin();
+            Question q = em.find(Question.class, questionId);
+            if (q != null && q.getReponse() != null) {
+                q.getReponse().getReponses().add(reponse);
+                em.merge(q);
+            }
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+        }
     }
 
-
-    public void deleteReponse( int questionId) {
+    public void deleteReponse(int questionId) {
         EntityTransaction t = em.getTransaction();
-        t.begin();
-        Question q = em.find(Question.class,questionId);
-
-        q.getReponse().setReponses(new ArrayList<>());
-        em.merge(q);
-        t.commit();
+        try {
+            if (!t.isActive()) t.begin();
+            Question q = em.find(Question.class, questionId);
+            if (q != null && q.getReponse() != null) {
+                q.getReponse().setReponses(new ArrayList<>());
+                em.merge(q);
+            }
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+        }
     }
 
-
     public void setReponse(Reponse rep, Integer id) {
         EntityTransaction t = em.getTransaction();
-        t.begin();
-        Question q = em.find(Question.class,id);
-        q.setReponse(rep);
-        em.merge(q);
-        t.commit();
+        try {
+            if (!t.isActive()) t.begin();
+            Question q = em.find(Question.class, id);
+            if (q != null) {
+                q.setReponse(rep);
+                em.merge(q);
+            }
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+        }
     }
 
-
     public void setChoix(Integer id) {
-        setReponse(new Choix(),id);
+        setReponse(new Choix(), id);
     }
 
     public void setReponseCourte(Integer id) {
-        setReponse(new ReponseCourte(),id);
+        setReponse(new ReponseCourte(), id);
     }
 
-
     public void addChoix(Integer id, String choix) {
         EntityTransaction t = em.getTransaction();
-        t.begin();
-        Question q = em.find(Question.class,id);
-
-        ((Choix)q.getReponse()).getChoix().add(choix);
-        em.merge(q);
-        t.commit();
+        try {
+            if (!t.isActive()) t.begin();
+            Question q = em.find(Question.class, id);
+            if (q != null && q.getReponse() instanceof Choix) {
+                ((Choix) q.getReponse()).getChoix().add(choix);
+                em.merge(q);
+            }
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+        }
     }
 
-
     public void changeQuestion(String newQuestion, Integer id) {
         EntityTransaction t = em.getTransaction();
-        t.begin();
-        Question q = em.find(Question.class,id);
-        q.setQuestion(newQuestion);
-        em.merge(q);
-        t.commit();
+        try {
+            if (!t.isActive()) t.begin();
+            Question q = em.find(Question.class, id);
+            if (q != null) {
+                q.setQuestion(newQuestion);
+                em.merge(q);
+            }
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+        }
     }
 }
 
diff --git a/src/main/java/fr/istic/taa/jaxrs/DAO/QuizzDAO.java b/src/main/java/fr/istic/taa/jaxrs/DAO/QuizzDAO.java
index fcd6c42..76887c4 100644
--- a/src/main/java/fr/istic/taa/jaxrs/DAO/QuizzDAO.java
+++ b/src/main/java/fr/istic/taa/jaxrs/DAO/QuizzDAO.java
@@ -10,23 +10,39 @@ public class QuizzDAO extends AbstractJpaDao<Integer, Quizz> {
         this.setClass(Quizz.class);
     }
 
-    public void deleteAllQustion(int quizz_id){
-        EntityTransaction et= em.getTransaction();
-        et.begin();
-        Quizz quizz = em.find(Quizz.class, quizz_id);
-        quizz.getQuestions().clear();
-        em.merge(quizz);
-        et.commit();
+    public void deleteAllQustion(int quizzId) {
+        EntityTransaction t = em.getTransaction();
+        try {
+            if (!t.isActive()) t.begin();
+            Quizz quizz = em.find(Quizz.class, quizzId);
+            if (quizz != null) {
+                quizz.getQuestions().clear();
+                em.merge(quizz); // ✅ merge instead of persist
+            }
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+            throw e;
+        }
     }
 
-    public void addQuestion(int quizz_id, int question_id){
-        EntityTransaction et= em.getTransaction();
-        et.begin();
-        Quizz quizz = em.find(Quizz.class, quizz_id);
-        Question question =em.find(Question.class, question_id);
+    public void addQuestion(int quizzId, int questionId) {
+        EntityTransaction t = em.getTransaction();
+        try {
+            if (!t.isActive()) t.begin();
+            Quizz quizz = em.find(Quizz.class, quizzId);
+            Question question = em.find(Question.class, questionId);
 
-        quizz.getQuestions().add(question);
-        em.merge(quizz);
-        et.commit();
+            if (quizz != null && question != null) {
+                quizz.getQuestions().add(question);
+                em.merge(quizz);
+            }
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+            throw e;
+        }
     }
 }
diff --git a/src/main/java/fr/istic/taa/jaxrs/DAO/SessionDAO.java b/src/main/java/fr/istic/taa/jaxrs/DAO/SessionDAO.java
index 0b29fec..0395a16 100644
--- a/src/main/java/fr/istic/taa/jaxrs/DAO/SessionDAO.java
+++ b/src/main/java/fr/istic/taa/jaxrs/DAO/SessionDAO.java
@@ -13,15 +13,21 @@ public class SessionDAO extends AbstractJpaDao<Integer, Session> {
         this.setClass(Session.class);
     }
 
-    public List<Session> findByTheme(String theme){
-        EntityTransaction t=em.getTransaction();
-        Query query=em.createQuery("select s from Session s where s.theme=:theme");
-        query.setParameter("theme",theme);
-        List<Session> sessions=query.getResultList();
-        if(sessions.size()>0){
+    public List<Session> findByTheme(String theme) {
+        EntityTransaction t = em.getTransaction();
+        try {
+            if (!t.isActive()) {
+                t.begin();
+            }
+            Query query = em.createQuery("SELECT s FROM Session s WHERE s.theme = :theme", Session.class);
+            query.setParameter("theme", theme);
+            List<Session> sessions = query.getResultList();
+            t.commit();
             return sessions;
-        }else{
-            return null;
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+            throw e;
         }
     }
 }
diff --git a/src/main/java/fr/istic/taa/jaxrs/DAO/UtilisateurDAO.java b/src/main/java/fr/istic/taa/jaxrs/DAO/UtilisateurDAO.java
index 89cf260..e704984 100644
--- a/src/main/java/fr/istic/taa/jaxrs/DAO/UtilisateurDAO.java
+++ b/src/main/java/fr/istic/taa/jaxrs/DAO/UtilisateurDAO.java
@@ -13,28 +13,53 @@ public class UtilisateurDAO extends AbstractJpaDao<Integer, Utilisateur> {
     }
 
     public Utilisateur findByEmail(String email) {
-        List<Utilisateur> results =
-                em.createQuery("SELECT u FROM Utilisateur u WHERE u.email = :email", Utilisateur.class)
-                        .setParameter("email", email).getResultList();
+        List<Utilisateur> results = em.createQuery(
+                        "SELECT u FROM Utilisateur u WHERE u.email = :email", Utilisateur.class)
+                .setParameter("email", email)
+                .getResultList();
+        return results.isEmpty() ? null : results.get(0);
+    }
 
-        if (results.isEmpty()) {
-            return null;
-        } else {
-            return results.get(0);
+    public void addToSession(int userId, int sessionId) {
+        EntityTransaction t = em.getTransaction();
+        try {
+            if (!t.isActive()) {
+                t.begin();
+            }
+
+            Session s = em.find(Session.class, sessionId);
+            Utilisateur u = em.find(Utilisateur.class, userId);
+
+            if (s == null || u == null) {
+                throw new IllegalArgumentException("User or session not found");
+            }
+
+            if (!u.getSession().contains(s)) {
+                u.getSession().add(s);
+                em.merge(u);
+            }
+
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+            throw e;
         }
     }
 
-    public void addToSession(int sessionId, int userId) {
+    @Override
+    public void create(Utilisateur entity) {
         EntityTransaction t = em.getTransaction();
-        t.begin();
-        Session s = em.find(Session.class, sessionId);
-        Utilisateur u = em.find(Utilisateur.class, userId);
-
-        //FAUT AJOUTER OWNING SIDE ( Ici u --> s)
-        u.getSession().add(s);
-        //Jsp il faut birectionnelle ou pas?
-        //s.getUtilisateurs().add(u);
-        em.merge(u);
-        t.commit();
+        try {
+            if (!t.isActive()) {
+                t.begin();
+            }
+            em.merge(entity);
+            t.commit();
+        } catch (Exception e) {
+            if (t.isActive()) t.rollback();
+            e.printStackTrace();
+            throw e;
+        }
     }
-}
+}
\ No newline at end of file