Explore the validation process for paytm in php

Setting Callback URL

Integrating Paytm with PHP involves a series of steps, including setting up a Paytm account, obtaining API credentials, and implementing the necessary code in your PHP application. Here's a step-by-step example:

Step 1: Create a Paytm Merchant Account
Visit the Paytm website and sign up for a merchant account.
Complete the necessary documentation and verification process.
Step 2: Obtain API Credentials
Log in to your Paytm Merchant account.
Navigate to the "Developer" section and obtain your Merchant ID, Merchant Key, Website, and Industry type.
Step 3: Download Paytm PHP Kit
Download the Paytm PHP Kit from the Paytm GitHub repository.
Extract the downloaded files to your project directory.
Step 4: Set Configuration Parameters
Open the paytm/PaytmKit/lib/config_paytm.php file and set the following parameters:

<?php
$PAYTM_MERCHANT_KEY = "your_merchant_key";
$PAYTM_MERCHANT_MID = "your_merchant_id";
$PAYTM_MERCHANT_WEBSITE = "your_website";
$PAYTM_CHANNEL_ID = "WEB";
$PAYTM_INDUSTRY_TYPE_ID = "Retail";
?>

Step 5: Create a Transaction Request
In your PHP code, create a transaction request and redirect the user to the Paytm payment gateway. Here's a simplified example:

<?php
require_once("paytm/PaytmKit/lib/config_paytm.php");
require_once("paytm/PaytmKit/lib/encdec_paytm.php");

// Set transaction parameters
$orderId = "ORDER" . time();
$amount = "10.00"; // Set your desired amount

// Create an array with transaction parameters
$paramList = array(
    "MID" => $PAYTM_MERCHANT_MID,
    "ORDER_ID" => $orderId,
    "CUST_ID" => "CUST" . time(),
    "TXN_AMOUNT" => $amount,
    "CHANNEL_ID" => $PAYTM_CHANNEL_ID,
    "WEBSITE" => $PAYTM_MERCHANT_WEBSITE,
    "INDUSTRY_TYPE_ID" => $PAYTM_INDUSTRY_TYPE_ID,
    "CALLBACK_URL" => "your_callback_url",
);

// Generate checksum
$checkSum = getChecksumFromArray($paramList, $PAYTM_MERCHANT_KEY);

// Add checksum to the parameters
$paramList["CHECKSUMHASH"] = $checkSum;

// Redirect the user to the Paytm payment page
?>
<html>
<head>
    <title>Paytm Payment Gateway Integration</title>
</head>
<body>
    <form method="post" action="https://securegw.paytm.in/theia/processTransaction" name="paytm_form">
        <?php
        foreach ($paramList as $name => $value) {
            echo '<input type="hidden" name="' . $name . '" value="' . $value . '">';
        }
        ?>
        <input type="submit" value="Proceed to Paytm">
    </form>
</body>
</html>

Step 6: Handle Callback
Once the payment is complete, Paytm will send a callback to the specified CALLBACK_URL. You need to handle this callback to update the payment status and perform any necessary actions in your application.

Practical Example

Setting Callback URL:

$paramList["CALLBACK_URL"] = "https://www.wizbrand.com/payment/pgResponse.php?ORDER_ID=$ORDER_ID&TXN_AMOUNT=$TXN_AMOUNT&admin_id=$admin_id&user_name=$user_name&create_date=$create_date&EMAIL=$EMAIL&created_date=$created_date";

This line constructs a callback URL by concatenating various parameters like ORDER_ID, TXN_AMOUNT, admin_id, etc., to the base URL "https://www.wizbrand.com/payment/pgResponse.php".
Checking Valid Checksum:
Step 7: Handle Callback in Your PHP Code
In your callback processing script (specified in the CALLBACK_URL), validate the callback status and update your database or perform any necessary actions:

<?php
require_once("paytm/PaytmKit/lib/config_paytm.php");
require_once("paytm/PaytmKit/lib/encdec_paytm.php");

// Verify the checksum
$paytmChecksum = isset($_POST["CHECKSUMHASH"]) ? $_POST["CHECKSUMHASH"] : "";
$isValidChecksum = verifychecksum_e($_POST, $PAYTM_MERCHANT_KEY, $paytmChecksum);

// Validate the callback status
if ($isValidChecksum == "TRUE" && $_POST["STATUS"] == "TXN_SUCCESS") {
    // Payment is successful, update your database or perform necessary actions
    $orderId = $_POST["ORDERID"];
    $transactionId = $_POST["TXNID"];
    $amount = $_POST["TXNAMOUNT"];

    // Perform actions like updating order status, sending email notifications, etc.
    // Example: Update order status in your database
    // $updateOrderQuery = "UPDATE orders SET status = 'completed' WHERE order_id = '$orderId'";
    // Execute the query as per your database structure and requirements

    // Example: Send email notification
    // mail($customerEmail, "Payment Success", "Thank you for your purchase!");

    echo "Payment successful. Order ID: $orderId, Transaction ID: $transactionId, Amount: $amount";
} else {
    // Payment failed or checksum mismatch, handle accordingly
    $orderId = isset($_POST["ORDERID"]) ? $_POST["ORDERID"] : "Unknown";
    echo "Payment failed for Order ID: $orderId";
}
?>

In this example, the script verifies the checksum and checks if the transaction status is "TXN_SUCCESS." If the payment is successful, you can update your database, send email notifications, or perform any other actions based on your application's requirements.

if($isValidChecksum == "TRUE") {

This conditional statement checks if the variable $isValidChecksum is equal to the string "TRUE".
Processing Successful Transaction:

if ($_POST["STATUS"] == "TXN_SUCCESS") {
    // Retrieve values from the URL parameters
    $ORDER_ID = $_GET['ORDER_ID'];
    $TXN_AMOUNT = $_GET['TXN_AMOUNT'];
    $admin_id = $_GET['admin_id'];
    $user_name = $_GET['user_name'];
    $create_date = $_GET['create_date'];
    $EMAIL = $_GET['EMAIL'];
    $created_date = $_GET['created_date'];

    // Construct redirect URL
    $redirect_url = "https://www.wizbrand.com/api/v1/j/view-laravel/$ORDER_ID/$TXN_AMOUNT/$admin_id/$user_name/$create_date/$EMAIL/$created_date";

    // Redirect to the constructed URL
    header("Location: $redirect_url");
}

If the transaction status ($_POST["STATUS"]) is "TXN_SUCCESS," it extracts values from the URL parameters and constructs a redirect URL. The user is then redirected to this URL.
Handling Unsuccessful Transaction:

else {
    // Display a modal indicating payment failure
    echo '...';  // HTML and JavaScript code for the modal
}

If the transaction status is not "TXN_SUCCESS," it displays a modal with a message indicating that the payment has failed.
Looping Through POST Parameters:

if (isset($_POST) && count($_POST)>0 )
{ 
    foreach($_POST as $paramName => $paramValue) {
        // Process each POST parameter
    }
}

If there are POST parameters, it loops through them and processes each one.

Please note that the provided code includes some HTML and JavaScript for displaying a modal in case of payment failure. The modal is shown with an error message, and there is a link to the cart page. Additionally, there's JavaScript code for handling the modal display and closure.

FULL CODE

$orderid = $_POST['ORDERID'];

$paytmChecksum = "";
$paramList = array();
$isValidChecksum = "FALSE";
$paramList = $_POST;
$paytmChecksum = isset($_POST["CHECKSUMHASH"]) ? $_POST["CHECKSUMHASH"] : ""; //Sent by Paytm pg
$isValidChecksum = verifychecksum_e($paramList, PAYTM_MERCHANT_KEY, $paytmChecksum); //will return TRUE or FALSE string.

if($isValidChecksum == "TRUE") {
    //echo "<b>Checksum matched and following are the transaction details:</b>" . "<br/>";
    if ($_POST["STATUS"] == "TXN_SUCCESS") {
        //update payment status
        $ORDER_ID = $_GET['ORDER_ID'];
$TXN_AMOUNT = $_GET['TXN_AMOUNT'];
$admin_id = $_GET['admin_id'];
$user_name = $_GET['user_name'];
$create_date = $_GET['create_date'];
$EMAIL = $_GET['EMAIL'];
$created_date = $_GET['created_date'];
$redirect_url = "https://www.wizbrand.com/api/v1/j/view-laravel/$ORDER_ID/$TXN_AMOUNT/$admin_id/$user_name/$create_date/$EMAIL/$created_date";

header("Location: $redirect_url");
    }
    else {
        echo '
        <div id="reject-influencer" class="modal fade" role="dialog">
                        <div class="modal-dialog">
                            <div class="modal-content">
                                <div class="modal-header" style="background-color:#d64a34;">
                                    <button type="button" style="color:white;" class="close"  data-dismiss="modal"> &times;</button>
                                    <br>                                    
                                </div>
                                <center> <div class="modal-body" style="background-color:#deb195a6;">
                                <div id="success-message" class="success-message">
                                <i class="fas fa-times-circle fa-3x" style="color: red;"></i>
                        <h5  class="text-center" style="margin-top: 10px; color: red;">Failed</h5>
                        <h5 id="rejectinfluencer" class="text-center" style="margin-top: 10px; color: green;">Your payment has failed</h5>

                        <!-- Button with link -->
                        <a href="https://www.wizbrand.com/cart" class="btn btn-primary">Go to cart</a>
                    </div>
                                </div></center>
                            </div>
                        </div>
                    </div>
        <script>
            // Show the modal
            var modal = document.getElementById("myModal");
            modal.style.display = "block";

            // Close the modal when clicking the close button
            var closeBtn = document.getElementsByClassName("close")[0];
            closeBtn.onclick = function() {
                modal.style.display = "none";
            }

            // Close the modal when clicking outside of it
            window.onclick = function(event) {
                if (event.target == modal) {
                    modal.style.display = "none";
                }
            }
        </script>';
    }

    if (isset($_POST) && count($_POST)>0 )
    { 
        foreach($_POST as $paramName => $paramValue) {
                //echo "<br/>" . $paramName . " = " . $paramValue;
        }
    }
}

Paytm process