JetSmartFilters. Filter JetEngine listing grid by author and post type.

filter-by-author-and-post-type.php

<?php

/**
 * Register new query variables for post type and author
 *
 * @param  array $vars Default query variables array
 * @return array
 */
function my_register_filter_query_vars( $vars ) {
	array_unshift( $vars, 'post_type', 'author' );
	return $vars;
}

add_filter( 'jet-smart-filters/query/vars', 'my_register_filter_query_vars' );

/**
 * Add required variables from request to filtered query arguments.
 * You can use this if you need to make some actions with $value before sending it into query
 *
 * @param  string $value Raw value from request.
 * @param  string $key   Raw key from request.
 * @param  string $var   Currently processed query variable name.
 * @param  object $query Jet_Smart_Filters_Query_Manager instance.
 * @return string
 */
function my_process_filter_query_vars( $value, $key, $var, $query ) {
	return $value;
}

add_filter( 'jet-smart-filters/query/add-var', 'my_process_filter_query_vars', 10, 4 );

/**
 * Remove aproppriate rows from meta query (because plugin is always added all unknown data as meta query)
 *
 * @param  array $row Meta query row.
 * @return array
 */
function my_clear_meta_query( $row ) {

	if ( in_array( $row['key'], array( 'author', 'post_type' ) ) ) {
		$row = array();
	}

	return $row;
}

add_filter( 'jet-smart-filters/query/meta-query-row', 'my_clear_meta_query' );

/**
 * Add required post types to initial query arguments
 * 188 - is listing ID which should be filterable. You need to replace it with your own.
 * 
 * @param  array  $args   Query arguments array
 * @param  object $widget Widget instance
 * @return array
 */
function my_add_initial_post_types_to_grid( $args, $widget ) {

	$settings = $widget->get_widget_settings();

	if ( empty( $settings['lisitng_id'] ) || 188 !== absint( $settings['lisitng_id'] ) ) {
		return $args;
	}

	$post_types = array_unique( array_merge(
		array( $args['post_type'] ),
		array( 'post', 'page', 'events', 'apartments' )
	) );

	$args['post_type'] = $post_types;

	return $args;
}

add_filter( 'jet-engine/listing/grid/posts-query-args', 'my_add_initial_post_types_to_grid', -1, 2 );