1 files changed, 18 insertions, 0 deletions
diff --git a/ishtar_common/utils.py b/ishtar_common/utils.py
index ff67fc470..94e71c655 100644
--- a/ishtar_common/utils.py
+++ b/ishtar_common/utils.py
@@ -929,3 +929,21 @@ def get_urls_for_model(model, views, own=False, autocomplete=False,
         ]
 
     return urls
+
+
+HISTORY_M2M_SPLIT = u"*||*"
+
+
+def m2m_historization_changed(sender, **kwargs):
+    obj = kwargs.get('instance', None)
+    if not obj:
+        return
+    for attr in obj.HISTORICAL_M2M:
+        values = []
+        for value in getattr(obj, attr).all():
+            if not hasattr(value, "history_compress"):
+                continue
+            values.append(value.history_compress())
+        setattr(obj, 'historical_' + attr, HISTORY_M2M_SPLIT.join(values))
+    obj.skip_history_when_saving = True
+    obj.save()