OSB-28: fix of the ActionLog object

LCU/Maintenance/DBInterface/monitoringdb/models/log.py

@@ -3,7 +3,7 @@ import django.db.models as models
 
 class ActionLog(models.Model):
     entry_id = models.IntegerField()
-    model_name = models.CharField(len=100)
-    who = models.CharField(len=100)
+    model_name = models.CharField(max_length=100)
+    who = models.CharField(max_length=100)
     when = models.DateTimeField(auto_now_add=True)
-    what = models.CharField(len=1000)
+    what = models.CharField(max_length=1000)

LCU/Maintenance/DBInterface/monitoringdb/serializers/log.py

@@ -4,8 +4,8 @@ import logging
 
 logger = logging.getLogger(__name__)
 
-class ActionLogSerializer():
 
+class ActionLogSerializer(ModelSerializer):
     class Meta:
         model = ActionLog
         fields = '__all__'