Raise error if we find users with the same letters, case-insensitive wise

api/views.py

@@ -59,7 +59,7 @@ class CustomAuthToken(APIView):
             user = CustomUser.objects.get(email=email)
             return user.username
         except ObjectDoesNotExist:
-            return None  # or handle the case where the user doesn't exist
+            return None
 
 class Logout(APIView):
     permission_classes = (IsAuthenticated,)

tournaments/signals.py

@@ -1,11 +1,12 @@
 import random
 import string
-from django.db.models.signals import post_save, pre_delete, post_delete
+from django.db.models.signals import pre_save, post_save, pre_delete, post_delete
 from django.dispatch import receiver
 from django.conf import settings
 from tournaments.models.tournament import Tournament
 from tournaments.models.unregistered_player import UnregisteredPlayer
 from django.utils import timezone
+from django.db.utils import IntegrityError
 
 from .models import Club, FailedApiCall, CustomUser, Log, TeamRegistration, PlayerRegistration, UnregisteredTeam, UnregisteredPlayer
 import requests
@@ -14,6 +15,12 @@ from tournaments.models import PlayerDataSource
 
 from shared.discord import send_discord_log_message, send_discord_failed_calls_message
 
+@receiver(pre_save, sender=CustomUser)
+def username_check(instance, sender, **kwargs):
+    """Ensure that username unique constraint is case insensitive"""
+    if sender.objects.filter(username__iexact=instance.username.lower()):
+        raise IntegrityError("Le nom d'utilisateur existe déjà")
+
 def generate_unique_code():
     characters = string.ascii_lowercase + string.digits
     while True: