JetSmartFilters Filter by year (for checkbox/select/radio filters compatibility)

jsf-year-filter.php

<?php

add_filter( 'jet-smart-filters/query/final-query', function( $query ) {

	if ( ! isset( $query['meta_query'] ) ) {
		return $query;
	}

	foreach ( $query['meta_query'] as $index => $meta_query_item ) {

		if ( false !== strpos( $meta_query_item['key'], 'by_years__' ) ) {

			$args = explode( '__', $meta_query_item['key'] );

			unset( $query['meta_query'][$index] );

			$column = $args[1] ?? '';

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

			$value = $meta_query_item['value'];

			if ( ! is_array( $value ) ) {
				$value = array( $value );
			}

			$date_query = array();

			foreach ( $value as $year ) {
				$date_query[] = array(
					'column' => $column,
					'year'   => $year,
				);
			}

			$date_query['relation'] = 'OR';

			$query['date_query'] = $date_query;

		}
		
	}

	return $query;

} );