Adding extra data to indexed entries in SearchWP

searchwp-customizations.php

<?php

// @link https://searchwp.com/documentation/knowledge-base/adding-extra-data-to-indexed-entries/
// Adding extra data to indexed entries in SearchWP.
add_filter( 'searchwp\entry\data', function( $data, \SearchWP\Entry $entry ) {
	$my_extra_meta_key = 'my_extra_meta';

	// SearchWP can index any data type, array/object values will all be processed.
	// For this example we will use a string:
	$my_extra_meta = 'This content will be searchable!';

	// Store custom Custom Field along existing postmeta.
	$data['meta'][ $my_extra_meta_key ] = $my_extra_meta;

	return $data;
}, 20, 2 );

// Add 'extra' meta as available option for your Source Attributes.
add_filter( 'searchwp\source\attribute\options', function( $keys, $args ) {
	if ( $args['attribute'] !== 'meta' ) {
		return $keys;
	}

	// This key is the same as the one used in the searchwp\entry\data hook above, they must be the same.
	$my_extra_meta_key = 'my_extra_meta';

	// Add "Extra Meta" Option if it does not exist already.
	if ( ! in_array(
		$my_extra_meta_key,
		array_map( function( $option ) { return $option->get_value(); }, $keys )
	) ) {
		$keys[] = new \SearchWP\Option( $my_extra_meta_key, 'Extra Meta' );
	}

	return $keys;
}, 20, 2 );