added salary table

app/models/loan.py

@@ -218,4 +218,14 @@ class Loan(db.Model):
         return cls.query.filter(
             cls.disburse_date.isnot(None),
             cls.disburse_verify.is_(None)
-        ).order_by(cls.created_at.desc()).first()
+        ).order_by(cls.created_at.desc()).first()
+        
+    @classmethod
+    def get_customer_loans(cls,  customer_id):
+        """
+        Get customer's active loans by customer_id.
+        """
+        customer_loans = cls.query.filter_by( customer_id = customer_id).all()
+        if not customer_loans:
+            raise ValueError(f"Customer with Id {customer_id} does not have any loan.")        
+        return customer_loans