Content type stored in logs instead of model name

apps/logs/models.py

@@ -1,6 +1,7 @@
 # Copyright (C) 2018-2020 by BDE ENS Paris-Saclay
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+from django.contrib.contenttypes.models import ContentType
 from django.utils.translation import gettext_lazy as _
 from django.conf import settings
 from django.core.exceptions import ValidationError
@@ -20,8 +21,9 @@ class Changelog(models.Model):
         verbose_name=_('user'),
     )
 
-    model = models.CharField(
+    model = models.ForeignKey(
-        max_length=255,
+        ContentType,
+        on_delete=models.PROTECT,
         null=False,
         blank=False,
         verbose_name=_('model'),

apps/logs/signals.py

@@ -3,6 +3,7 @@
 
 import inspect
 
+from django.contrib.contenttypes.models import ContentType
 from django.core import serializers
 from django.db.models.signals import pre_save, pre_delete
 from django.dispatch import receiver
@@ -44,7 +45,7 @@ def save_object(sender, instance, **kwargs):
         previous_json = None
     instance_json = serializers.serialize('json', [instance, ],)[1:-1]
     Changelog.objects.create(user=user,
-                                        model=model_name,
+                                        model=ContentType.objects.get_for_model(instance),
                                         instance_pk=instance.pk,
                                         previous=previous_json,
                                         data=instance_json,