[add]: Update loan status after repayment

app/models/loan.py

@@ -65,16 +65,35 @@ class Loan(db.Model):
             return False
         return True
     
+
     @classmethod
     def get_customer_loan(cls, loan_id, customer_id):
         """
-        Check if a loan with the given ID exists and if the loan belongs to the specified customer_id.
+        Get customer's active loans.
         """
-        loan = cls.query.filter_by(id=loan_id, customer_id=customer_id).first()
+        loan = cls.query.filter_by(id = loan_id, customer_id = customer_id).first()
         if not loan:
-            raise ValueError(f"Loan with ID {loan_id} does not exist or does not belong to customer {customer_id}.")
+            raise ValueError(f"Loan with ID {loan_id} does not exist or does not belong to customer {customer_id}.")        
         return loan
     
+    @classmethod
+    def update_status(cls, loan_id, status):
+        """
+        Update the status of the loan with the given loan_id.
+        """
+        # Retrieve loan 
+        loan = cls.query.get(loan_id)
+        
+        if not loan:
+            raise ValueError(f"Loan with ID {loan_id} does not exist.")
+        
+        if loan.status == status:
+            return
+        
+        # Update loan status and the updated_at timestamp
+        loan.status = status
+        
+        db.session.commit()
     
     def __repr__(self):
         return f'<Loan {self.id}>'