Verify IPN Call

When the payment is completed, VNPay will send an IPN (Instant Payment Notification) call to the IPN URL that you have set up. To verify the IPN call, you can use the VNPay library.

Verify IPN

import { VerifyIpnCall } from 'vnpay';

/* ... */

const verify: VerifyIpnCall = vnpay.verifyIpnCall(req.query);

Properties of the VerifyIpnCall Object

Information after verification and returned by VNPay:

Property	Data Type	Description
isSuccess	boolean	The result of the payment order
isVerified	boolean	The result of verifying the integrity of the data received from VNPay
message	string	Verification message
vnp_Amount	number	The payment amount, automatically calculated by the library
...	...	Other parameters returned by VNPay, refer to official documentation

See more properties that VNPay will return in the official documentation.

tip

All parameters returned by VNPay are also included in the VerifyIpnCall object.

Usage

Using Logger

• Similar to when creating a payment URL, you can use a logger to log IPN verification information see here.

With Express

Steps to verify the IPN call in Express:

1. Create a route to handle the IPN call
2. Verify the IPN call
3. Process the information returned from VNPay
4. Update the order status in your database
5. Update the status back to VNPay to confirm that you have received and processed the order

controllers/payment.controller.ts

import {
    IpnFailChecksum,
    IpnOrderNotFound,
    IpnInvalidAmount,
    InpOrderAlreadyConfirmed,
    IpnUnknownError,
    IpnSuccess,
} from 'vnpay';

/* ... */

app.get('/vnpay-ipn', async (req, res) => {
    try {
        const verify: VerifyReturnUrl = vnpay.verifyIpnCall(req.query);
        if (!verify.isVerified) {
            return res.json(IpnFailChecksum);
        }

        if (!verify.isSuccess) {
            return res.json(IpnUnknownError);
        }

        // Find the order in your database
        const foundOrder = await findOrderById(verify.vnp_TxnRef); // Method to find an order by id, you need to implement it

        // If the order is not found or the order code does not match
        if (!foundOrder || verify.vnp_TxnRef !== foundOrder.orderId) {
            return res.json(IpnOrderNotFound);
        }

        // If the payment amount does not match
        if (verify.vnp_Amount !== foundOrder.amount) {
            return res.json(IpnInvalidAmount);
        }

        // If the order has been confirmed before
        if (foundOrder.status === 'completed') {
            return res.json(InpOrderAlreadyConfirmed);
        }

        /**
         * After verifying the order is complete,
         * you can update the order status in your database
         */
        foundOrder.status = 'completed';
        await updateOrder(foundOrder); // Function to update the order status, you need to implement it

        // Then update the status back to VNPay to let them know that you have confirmed the order
        return res.json(IpnSuccess);
    } catch (error) {
        /**
         * Handle exceptions
         * For example, insufficient data, invalid data, database update failure
         */
        console.log(`verify error: ${error}`);
        return res.json(IpnUnknownError);
    }
});