[add]: Loan repayment event

app/models/customer.py

@@ -2,6 +2,7 @@ from datetime import datetime, timezone
 from sqlalchemy.orm import relationship
 from app.extensions import db
 from app.models.account import Account
+from sqlalchemy.exc import IntegrityError
 
 class Customer(db.Model):
     __tablename__ = 'customers'
@@ -33,16 +34,20 @@ class Customer(db.Model):
         
         # Create the customer
         customer = cls(id=id, msisdn=msisdn, country_code=country_code)
-        db.session.add(customer)
-        
-        # Create an associated account
-        account = Account.create_account(
-            id=account_id,
-            customer_id=id,
-            account_type=account_type
-        )
-        
-        db.session.commit()
+        try: 
+            db.session.add(customer)
+            
+            # Create an associated account
+            account = Account.create_account(
+                id=account_id,
+                customer_id=id,
+                account_type=account_type
+            )
+            
+            db.session.commit()
+        except IntegrityError as err:
+            db.session.rollback()
+            raise ValueError(f"Database integrity error: {err}")
         return customer
 
     def __repr__(self):