Automatically link to WooCommerce Product Variation permalink in SearchWP.

searchwp-customizations.php

<?php

// @link https://searchwp.com/documentation/knowledge-base/add-woocommerce-product-variations-to-products/

// When using SearchWP it's necessary to disable WooCommerce's insistance on
// automatically redirecting to a single search result without showing the
// search results page, when that happens this hook doesn't run!
// Willing to bet this can be edited to accommodate, tips are welcome!
add_filter( 'woocommerce_redirect_single_search_result', '__return_false' );

add_filter( 'post_type_link', function( $permalink, $post ) {
	if ( ! is_search() || 'product' !== get_post_type( $post ) ) {
		return $permalink;
	}

	$search_query = \SearchWP\Utils::get_string_from( get_search_query() );

	// If this is a search for a Variation SKU we can bail out early.
	$variation_from_sku = get_posts( [
		'post_type'      => 'product_variation',
		'posts_per_page' => 1,
		'fields'         => 'ids',
		'meta_query'     => [ [
			'key'     => '_sku',
			'value'   => $search_query,
		], ]
	] );

	// Make sure (if there is one) the Variation is for the parent Product.
	if ( ! empty( $variation_from_sku ) ) {
		// This is a Variation SKU.
		$variation_id  = absint( $variation_from_sku[0] );
		$variation_obj = new WC_Product_Variation( $variation_id );
		$attributes    = $variation_obj->get_variation_attributes();

		if ( empty( $attributes ) ) {
			return $permalink;
		}

		return add_query_arg( $attributes, $permalink );
	}

	// Determine if this Product has any Variations.
	$product_variations = get_posts( [
		'post_type'       => 'product_variation',
		'posts_per_page'  => -1,
		'fields'          => 'ids',
		'post_parent'     => $post->ID,
	] );

	if ( empty( $product_variations ) || ! class_exists( 'WC_Product_Variation' ) ) {
		return $permalink;
	}

	// Check to see if any search terms match any Variation Attributes.
	foreach ( $product_variations as $variation_id ) {
		$variation_obj = new \WC_Product_Variation( $variation_id );
		$attributes = $variation_obj->get_variation_attributes();

		if ( empty( $attributes ) ) {
			continue;
		}

		$search_query = \SearchWP\Utils::clean_string( $search_query );

		foreach ( $attributes as $attribute_tax => $attribute_value ) {
			foreach ( explode( ' ', $attribute_value ) as $value ) {
				$value = \SearchWP\Utils::clean_string( \SearchWP\Utils::get_string_from( $value ) );
				if ( false !== strpos( $search_query, $value ) ) {
					$permalink = add_query_arg( [ $attribute_tax => urlencode( $attribute_value ) ], $permalink );

					continue;
				}
			}
		}
	}

	return $permalink;
}, 99, 2 );