1 files changed, 9 insertions, 1 deletions
diff --git a/ishtar_common/models.py b/ishtar_common/models.py
index 15b341cb7..7aa8706b3 100644
--- a/ishtar_common/models.py
+++ b/ishtar_common/models.py
@@ -21,6 +21,7 @@
 Models description
 """
 import copy
+from collections import OrderedDict
 import datetime
 import inspect
 from importlib import import_module
@@ -1929,7 +1930,14 @@ class TemplateItem:
         return cls._label_templates_q()
 
 
-class BaseHistorizedItem(TemplateItem, FullSearch, Imported,
+class StatisticItem:
+    STATISTIC_MODALITIES = []  # example: "operation type", "material type"
+    STATISTIC_SUM_VARIABLE = OrderedDict(
+        (("pk", _("number")),)
+    )  # example: "price", "volume"
+
+
+class BaseHistorizedItem(StatisticItem, TemplateItem, FullSearch, Imported,
                          JsonData, FixAssociated):
     """
     Historized item with external ID management.