1 files changed, 29 insertions, 0 deletions
diff --git a/ishtar_common/models.py b/ishtar_common/models.py
index 53d5c85ac..55795c91e 100644
--- a/ishtar_common/models.py
+++ b/ishtar_common/models.py
@@ -175,6 +175,35 @@ class ValueGetter(object):
         return values
 
 
+class ExternalIdManager(object):
+    EXTERNAL_ID_KEY = ''
+    EXTERNAL_ID_DEPENDENCIES = []
+
+    def update_external_id(self, save=True):
+        if not self.EXTERNAL_ID_KEY:
+            raise NotImplementedError(
+                "{} should have an EXTERNAL_ID_KEY".format(self.__class__))
+        if self.external_id and not self.auto_external_id:
+            return
+        external_id = get_external_id(self.EXTERNAL_ID_KEY, self)
+        if external_id == self.external_id:
+            return
+        self.auto_external_id = True
+        self.external_id = external_id
+        if save:
+            self.skip_history_when_saving = True
+            self.save()
+        for dep in self.EXTERNAL_ID_DEPENDENCIES:
+            for obj in getattr(self, dep).all():
+                obj.update_external_id()
+        return external_id
+
+    def save(self, *args, **kwargs):
+        returned = super(ExternalIdManager, self).save(*args, **kwargs)
+        self.update_external_id()
+        return returned
+
+
 class HistoricalRecords(BaseHistoricalRecords):
     def create_historical_record(self, instance, type):
         try: