How to dynamically assign an order value to a Google Ads conversion tracking script

I have an e-commerce store powered by WHMCS, and I have a Google Ads campaign I'd like to set up conversion tracking for.

Google Ads has given me the following code to track conversions on my WHMCS site.

<script>
  gtag('event', 'conversion', {
      'send_to': 'AW-xxx/xxx',
      'value': 10.0,
      'currency': 'AUD',
      'transaction_id': ''
  });
</script>

During the Google Ads conversion setup, they asked for a default conversion value which I set to AU$10.

I've added that conversion script to the complete.tpl file.

How do I dynamically set the value assigned to the Google Ads conversion based on the order that has just been made in on the order complete page?

I have the Google Analytics WHMCS app installed and configured.

I see there is no WHMCS Google Ads app.

Solution

Not sure about the Google Ads, but I integrated Google Analytics 4 before stumbling upon the WHMCS app. So you can follow the same for Google Ads

First off, create a custom hook file in includes\hooks
In the file, create a hook for defining Google Ads calling script in the head tag (For further details, please see ClientAreaHeadOutput):
```
add_hook('ClientAreaHeadOutput', 1, function ($vars) {
    return '<script>Google Ads Script Here</script>';
});
```
Add another hook for the noscript code in start of the body tag, if there is any (For further details, please see ClientAreaHeaderOutput):
```
add_hook('ClientAreaHeaderOutput', 1, function ($vars) {
    return "<noscript>No Script Code Here</noscript>";
});
```

Add another hook that will mark conversion when the invoice is paid, I have customized it to what you require (For further details, please see InvoicePaid):

add_hook('InvoicePaid', 1, function ($vars) {
    $invoiceID = $vars['invoiceid'];
    $order = Capsule::table('tblorders')->where('invoiceid', '=', $invoiceID)->first();

    if ($order !== null) { // order exists
        $transactionID = $order->id;

        $orders = localAPI('GetOrders', array('id' => $transactionID));
        $order = $orders['orders']['order'][0];

        $result = localAPI('GetClientsDetails', array('clientid' => $order['userid']));
        $client = $result['client'];

        $currencyCode = $client["currency_code"];

        $total = 0;
        foreach ($order['lineitems']['lineitem'] as $product) {
            // get actual product pricing
            $price = (float)preg_replace("/[^\\d.]+/", "", $product['amount']);
            if ($product['type'] == 'product') {
                $tempItem = Capsule::table('tblhosting')->where('id', '=', $product['relid'])->first();
                if ($tempItem != NULL) {
                    $actualProduct = getProduct($product['pid']); // fetch original product for actual pricing

                    $selectedCycle = strtolower($product['billingcycle']);
                    $price = (float)$actualProduct['pricing'][$currencyCode][$selectedCycle];
                }
            }

            $total += $price;
        }

        return "
            <script>
                gtag('event', 'conversion', {
                    'send_to': 'AW-xxx/xxx',
                    'value': " . (float)$total . ",
                    'currency': '" . $currencyCode . "',
                    'transaction_id': '" . $transactionID . "'
                });
            </script>";
    }
});

Also don't forget to include the Capsule on top of the file as:

use Illuminate\Database\Capsule\Manager as Capsule;