leaky-paywall-datalayer.php

<?php

add_action( 'wp_footer', 'zeen101_add_transaction_event_code' );

function zeen101_add_transaction_event_code() {

	if ( ! isset( $_GET['lp_txn_id'] ) ) {
		return;
	}

	$txn_id = absint( $_GET['lp_txn_id'] );
	$price = get_post_meta( $txn_id, '_price', true );
	$level_id = get_post_meta( $txn_id, '_level_id', true );
	$level = get_leaky_paywall_subscription_level( $level_id );

	?>

	<script>
	gtag("event", "purchase", {
	    transaction_id: "<?php echo $txn_id; ?>",
	    value: <?php echo $level['price']; ?>,
	    currency: "USD",
	    items: [
	     {
	      item_id: "<?php echo $level_id; ?>",
	      item_name: "<?php echo $level['label']; ?>",
	      affiliation: "Your Publication",
	      index: 0,
	      item_brand: "Your Publication",
	      item_category: "Subscription",
	      price: <?php echo $level['price']; ?>,
	      quantity: 1
	    },
	}]
	});
	</script>

	<?php 
}