Give extra weight to entries within a Category, Tag, or Taxonomy Term in SearchWP

functions.php

<?php

function my_searchwp_weight_mods( $sql ) {
	global $wpdb;

	$swp_db_prefix = $wpdb->prefix . SEARCHWP_DBPREFIX;
		
	// These are the taxonomy terms we want to give bonus weight.
	$bonuses = array(
		array(
			'term_id'      => 17,   // The taxonomy term ID to give the bonus weight.
			'bonus_weight' => 1000, // The bonus weight to give this taxonomy term.
		),
		array(
			'term_id'      => 88,   // The taxonomy term ID to give the bonus weight.
			'bonus_weight' => 300,  // The bonus weight to give this taxonomy term.
		),
	);
		
	foreach ( $bonuses as $bonus ) {
		$sql .= " + ( IF ((
			SELECT {$wpdb->prefix}posts.ID
			FROM {$wpdb->prefix}posts
			LEFT JOIN {$wpdb->prefix}term_relationships ON (
				{$wpdb->prefix}posts.ID = {$wpdb->prefix}term_relationships.object_id
			)
			WHERE {$wpdb->prefix}posts.ID = {$swp_db_prefix}index.post_id
				AND {$wpdb->prefix}term_relationships.term_taxonomy_id = {$bonus['term_id']}
			LIMIT 1
		) > 0, {$bonus['bonus_weight']}, 0 )) ";
	}
		
	return $sql;
}

add_filter( 'searchwp_weight_mods', 'my_searchwp_weight_mods', 20 );