Refactor group and music game models to use UniqueConstraint; update form error handling in templates

game/views.py

@@ -7,6 +7,7 @@ from django.conf import settings
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.contrib.auth.models import User
 from django.contrib.messages.views import SuccessMessageMixin
+from django.db import IntegrityError
 from django.db.models import Count, Q
 from django.http import JsonResponse
 from django.shortcuts import get_object_or_404, redirect
@@ -40,7 +41,11 @@ class GroupMixin:
 class GroupCreateView(LoginRequiredMixin, GroupMixin, CreateView):
     def form_valid(self, form):
         form.instance.owner = self.request.user
-        return super().form_valid(form)
+        try:
+            return super().form_valid(form)
+        except IntegrityError:
+            form.add_error("name", "Ce nom de groupe existe déjà.")
+            return super().form_invalid(form)
 
 
 class GroupUpdateView(OwnerFilterMixin, GroupMixin, UpdateView):