replaced StatsLog.model with a generic foreign key

stats/models.py

@@ -1,5 +1,6 @@
 from django.contrib.gis.db import models
 from django.contrib.contenttypes.models import ContentType
+from django.contrib.contenttypes.fields import GenericForeignKey
 from django.contrib.auth import get_user_model
 
 User = get_user_model()
@@ -7,7 +8,14 @@ User = get_user_model()
 
 class StatsLog(models.Model):
 
-    model = models.ForeignKey(ContentType, on_delete=models.DO_NOTHING, null=True)
+    action_object_content_type = models.ForeignKey(
+        ContentType, blank=True,
+        null=True,
+        related_name='statslogs',
+        on_delete=models.CASCADE
+        )
+    action_object_object_id = models.CharField(max_length=255, blank=True, null=True)
+    action_object = GenericForeignKey('action_object_content_type', 'action_object_object_id')
     user = models.ForeignKey(User, on_delete=models.DO_NOTHING, null=True)
     anonymous = models.BooleanField('Usuario no registrado', null=True)
     ip_address = models.GenericIPAddressField('IP usuario', null=True, blank=True)