fixed creating group room for multiple professors

apps/course/signals.py

@@ -9,7 +9,7 @@ from django.db.models import Q
 
 logger = logging.getLogger(__name__)
 
-from django.db.models.signals import post_save, post_delete, pre_save
+from django.db.models.signals import post_save, post_delete, pre_save, m2m_changed
 from django.dispatch import receiver
 from django.core.cache import cache
 from django.contrib.auth import get_user_model
@@ -17,10 +17,39 @@ from django.contrib.auth import get_user_model
 UserModel = get_user_model()
 
 
+def sync_course_group_room(instance):
+    title_str = extract_text_from_json(instance.title)
+    first_professor = instance.professors.first()
+
+    if first_professor:
+        RoomMessage.objects.update_or_create(
+            course=instance,
+            room_type=RoomMessage.RoomTypeChoices.GROUP,
+            defaults={
+                "name": f"{title_str} - Group",
+                "description": f"Group chat for course: {title_str}",
+                "initiator": first_professor,
+            },
+        )
+    else:
+        # In create flows, professors may be assigned after the initial save.
+        # Keep metadata synced, but avoid creating an invalid room with null initiator.
+        RoomMessage.objects.filter(
+            course=instance,
+            room_type=RoomMessage.RoomTypeChoices.GROUP
+        ).update(
+            name=f"{title_str} - Group",
+            description=f"Group chat for course: {title_str}",
+        )
+
+
 @receiver(post_save, sender=Course)
 def handle_room_message_for_course(sender, instance, created, **kwargs):
     title_str = extract_text_from_json(instance.title)
     first_professor = instance.professors.first()
+    if created and not first_professor:
+        return
+
     if created:  # فقط برای موارد جدید اجرا شود
         RoomMessage.objects.create(
             name=f"{title_str} - Group",
@@ -43,6 +72,19 @@ def handle_room_message_for_course(sender, instance, created, **kwargs):
         ).update(**update_kwargs)
 
 
+@receiver(m2m_changed, sender=Course.professors.through)
+def handle_course_professors_changed(sender, instance, action, pk_set, **kwargs):
+    if action not in {"post_add", "post_remove", "post_clear"}:
+        return
+
+    sync_course_group_room(instance)
+
+    for professor in instance.professors.all():
+        professor.ensure_professor_profile()
+        detail_cache_key = f"professor_detail_{professor.slug}"
+        cache.delete(detail_cache_key)
+
+
 @receiver(post_save, sender=Course)
 def ensure_professor_role(sender, instance, **kwargs):
     for professor in instance.professors.all():