functions.php

<?php

add_filter( 'facetwp_indexer_post_facet', 'fwp_index_wpjmfe_serialized', 15, 2 );

/**
 * Filter FacetWP indexing to index WP Job Manager fields
 *
 * Some WP Job Manager fields are saved as serialized arrays, and due to this, we need to
 * make sure and unserialize that data to make it indexable.  This will also index normal
 * WP Job Manager fields that are not serialized.
 *
 * This method uses the `facetwp_indexer_post_facet` filter that runs before FacetWP attempts to
 * get the data itself.  If we return the $falsey variable (which is FALSE by default), FacetWP
 * will attempt to pull the data itself, if we return TRUE, it will not, and will move on to
 * the next Facet in the loop.
 *
 *
 * @since @@version
 *
 * @param $falsey   boolean     Normally FALSE to allow FacetWP to handle pulling data to index
 * @param $config   array       Array of configuration data, includes the `defaults` and `facet` keys.
 *
 * @return boolean              Return TRUE to prevent FacetWP from pulling data to index, FALSE to allow it to
 */
function fwp_index_wpjmfe_serialized( $falsey, $config ){

	$params = $config['defaults'];
	$post_type = isset( $params['post_id'] ) ? get_post_type( $params['post_id'] ) : 'unknown';
	$wpjm_post_types = array( 'job_listing', 'resume' );

	/**
	 * Exit if user already has custom function, or if the post type is not a supported post type
	 */
	if( function_exists( 'fwp_index_wpjmfe' ) || ! in_array( $post_type, $wpjm_post_types )) return $falsey;

	$fields     = WP_Job_Manager_Field_Editor_Fields::get_instance();
	$all_fields = $fields->get_fields();

	/**
	 * Get FacetWP Indexer Class Object
	 */
	$indexer = function_exists( 'FWP' ) && FWP()->indexer instanceof FacetWP_Indexer ? FWP()->indexer : FALSE;

	/**
	 * Exit if error getting fields, indexer class object, or not custom field facet source.
	 * WP Job Manager custom field sources will always have the prepended underscore for the meta key.
	 */
	if( empty( $all_fields ) || empty( $indexer ) || strpos( $params['facet_source'], 'cf/_' ) === FALSE ) return $falsey;

	/**
	 * Get meta key, without prepended underscore
	 */
	$cf_name = str_replace( 'cf/_', '', $params['facet_source'] );

	foreach( $all_fields as $field_group => $fields ) {

		/**
		 * Meta key not found in this field group
		 */
		if( ! array_key_exists( $cf_name, $fields ) ) continue;

		$values = maybe_unserialize( get_post_meta( $params['post_id'], "_{$cf_name}", TRUE ) );
		settype( $values, 'array' );

		/**
		 * This is our meta key, but we don't have any values
		 */
		if( empty( $values ) || empty( $values[0] ) ) return TRUE;

		/**
		 * Add values to FacetWP Index Table
		 */
		foreach( $values as $val ) {
			$params['facet_value']         = $val;
			$params['facet_display_value'] = $val;

			/**
			 * Pass params through core FacetWP filter just in case
			 */
			$params = apply_filters( 'facetwp_index_row', $params, FWP()->indexer );

			if( ! empty( $params ) ) $indexer->insert( $params );

		}

		/**
		 * Prevent FacetWP from trying to insert, since we already have
		 */
		return TRUE;

	}

	/**
	 * Return false to let FacetWP handle it
	 */
	return $falsey;
}