ElasticPress: Make Elasticsearch search for the string in different fields

ep-add-cross-fields.php

<?php

/**
 * Add a cross_field type clause to the ES query, so it searches for terms
 * in different fields.
 *
 * @param array  $query         Current query
 * @param array  $args          Query variables
 * @param string $search_text   Search text
 * @param array  $search_fields Search fields
 * @return array
 */
function ep_formatted_args_query( $query, $args, $search_text, $search_fields ) {
	if ( ! @isset( $query['bool']['should'] ) ) {
		return $query;
	}

	$query['bool']['should'][] = [
		'multi_match' => [
			'query'       => $search_text,
			'type'        => 'cross_fields',
			'fields'      => $search_fields,
			'boost'       => 1,
			'analyzer'    => 'standard',
			'tie_breaker' => 0.5,
			'operator'    => 'and',
		],
	];

	return $query;
}
add_filter( 'ep_formatted_args_query', 'ep_formatted_args_query', 10, 4 );

/**
 * Apply `1` as the weight for the cross_field clause.
 *
 * @param string $weighted_field The field and its weight as used in the ES query.
 * @param string $field          Field name
 * @param string $weight         Weight value
 * @param array  $fieldset       Current subset of formatted ES args
 * @return array New weighted field string
 */
function adjust_weight_for_cross_fields( $weighted_field, $field, $weight, $fieldset ) {
	if ( 'cross_fields' === $fieldset['type'] ) {
		$weighted_field = "{$field}^1";
	}
	return $weighted_field;
}
add_filter( 'ep_query_weighting_fields', 'adjust_weight_for_cross_fields', 10, 5 );