Fires WooCommerce purchase event on thankyou page.

fire-purchase-event.php

<?php

/**
 * Push GA4 purchase to dataLayer directly from WooCommerce thankyou hook.
 * - Fires exactly when woocommerce_thankyou runs (confirmed on your site)
 * - Includes a per-order/browser dedupe guard
 * - Uses GA4-standard ecommerce payload (transaction_id, value, items, etc.)
 */

add_action( 'woocommerce_thankyou', function ( $order_id ) {
	if ( ! $order_id || ! function_exists( 'wc_get_order' ) ) {
		return;
	}
	$order = wc_get_order( $order_id );
	if ( ! $order ) {
		return;
	}

	// Only successful purchases (adjust if you also want 'on-hold' or 'completed' only)
	if ( ! $order->has_status( array( 'processing', 'completed' ) ) ) {
		return;
	}

	$currency = $order->get_currency();
	$value    = (float) $order->get_total();
	$tax      = (float) $order->get_total_tax();
	$shipping = (float) $order->get_shipping_total();
	$coupon   = $order->get_coupon_codes() ? implode( ',', $order->get_coupon_codes() ) : '';

	$items = array();
	foreach ( $order->get_items() as $item_id => $item ) {
		$product   = $item->get_product();
		$sku_or_id = $product ? ( $product->get_sku() ?: $product->get_id() ) : $item_id;
		$cat_path  = '';
		if ( $product && function_exists( 'wc_get_product_category_list' ) ) {
			$cat_path = wp_strip_all_tags( wc_get_product_category_list( $product->get_id(), ' / ' ) );
		}
		$items[] = array(
			'item_id'       => (string) $sku_or_id,
			'item_name'     => (string) $item->get_name(),
			'quantity'      => (int) $item->get_quantity(),
			'price'         => (float) $order->get_item_total( $item, false, true ), // unit price ex tax
			'item_category' => $cat_path ?: '',
		);
	}

	$payload = array(
		'transaction_id' => (string) $order->get_order_number(),
		'value'          => $value,
		'currency'       => $currency,
		'tax'            => $tax,
		'shipping'       => $shipping,
		'coupon'         => $coupon,
		'items'          => array_values( $items ),
	);

	// Print the push right where the hook runs (works even if wp_footer is missing)
	// Includes a sessionStorage guard to avoid re-push on reload/back
	echo '<script id="emx-purchase-' . (int) $order_id . '">';
	echo '(function(){try{';
	echo 'var k="emx_purchase_pushed_' . (int) $order_id . '";';
	echo 'if(sessionStorage.getItem(k))return;';
	echo 'window.dataLayer=window.dataLayer||[];';
	echo 'dataLayer.push({event:"purchase",ecommerce:' . wp_json_encode( $payload ) . '});';
	// Optional: also push GTM4WP legacy name in case your trigger listens for it
	echo 'dataLayer.push({event:"gtm4wp.orderCompletedEEC",ecommerce:' . wp_json_encode( $payload ) . '});';
	// Clear ecommerce object to prevent accidental reuse
	echo 'dataLayer.push({ecommerce:null});';
	echo 'sessionStorage.setItem(k,"1");';
	echo 'console.log("[emx] purchase pushed for order #' . (int) $order_id . '", ' . wp_json_encode( $payload ) . ');';
	echo '}catch(e){console&&console.warn&&console.warn("emx purchase push error",e);} })();';
	echo '</script>' . "\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped

	// Tiny HTML breadcrumb for quick view-source debugging
	echo "\n<!-- emx: pushed GA4 purchase for order #{$order_id} -->\n";
}, 20 );