model class update total cal fields all model

app/models/trench_excavation_model.py

@@ -1,5 +1,6 @@
 from app import db
 from datetime import datetime
+from sqlalchemy import event
 
 class TrenchExcavation(db.Model):
     __tablename__ = "trench_excavation"
@@ -108,3 +109,17 @@ class TrenchExcavation(db.Model):
                 + safe(self.Hard_Rock_6_0_to_7_5)
             ),
         }
+
+# ==========================================
+# AUTO CALCULATE GRAND TOTAL
+# ==========================================
+def calculate_trench_total(mapper, connection, target):
+    total = 0
+    for column in target.__table__.columns:
+        if column.name.endswith("_total"):
+            total += getattr(target, column.name) or 0
+    target.Total = total
+
+
+event.listen(TrenchExcavation, "before_insert", calculate_trench_total)
+event.listen(TrenchExcavation, "before_update", calculate_trench_total)