Always send the parent product ID to Google Analytics 4

always-send-the-parent-product-id-to-google-analytics-4.php

<?php
/**
 * SEOPress PRO — Always send the parent product ID to Google Analytics 4.
 *
 * By default SEOPress sends the variation SKU (or, as fallback, the variation ID)
 * for each line item in a WooCommerce order. Some shops prefer to aggregate
 * analytics at the parent product level — e.g. a single "Blue T-Shirt" row in GA4
 * instead of one row per size / color variation. This snippet returns the SKU
 * (or ID) of the parent product whenever a variation is purchased.
 *
 * Hook: seopress_gtag_ec_item_id
 * Plugin: SEOPress PRO 9.9+
 * Requires: WooCommerce
 */

add_filter( 'seopress_gtag_ec_item_id', 'sp_gtag_ec_item_id', 10, 4 );
function sp_gtag_ec_item_id( $item_id, $product, $item, $order ) {
	if ( ! is_a( $product, 'WC_Product' ) ) {
		return $item_id;
	}

	// Only override for variations — keep the default for simple products.
	if ( ! $product->is_type( 'variation' ) ) {
		return $item_id;
	}

	$parent_id = $product->get_parent_id();
	if ( ! $parent_id ) {
		return $item_id;
	}

	$parent = wc_get_product( $parent_id );
	if ( ! is_a( $parent, 'WC_Product' ) ) {
		return $item_id;
	}

	return $parent->get_sku() ? $parent->get_sku() : $parent->get_id();
}