WordPress: Taxonomy dropdown for admin list filter

wp-taxonomy-dropdown.php

/**
 * Outputs a taxonomy dropdown list.
 *
 * @param  string $taxonomy The taxonomy name
 * @param  array  $args     Additional args.
 * @return void
 */
function taxonomy_dropdown( $taxonomy, $args = [] ) {

	if ( ! taxonomy_exists( $taxonomy ) ) {
		return;
	}

	$taxonomy = get_taxonomy( $taxonomy );

	$args = wp_parse_args(
		$args,
		[
			'all_items_label' => $taxonomy->labels->all_items,
			'selected_term'   => filter_input( INPUT_GET, $taxonomy->name, FILTER_SANITIZE_STRING ),
			'terms'           => get_terms( $taxonomy->name, array( 'hide_empty' => true ) ),
			'name'            => $taxonomy->name,
			'id'              => 'dropdown-' . $taxonomy->name,
		]
	);

	$args = apply_filters( __FUNCTION__, $args, $taxonomy );

	?>
		<select name="<?php echo esc_attr( $args['name'] ); ?>" id="<?php echo esc_attr( $args['id'] ); ?>">
			<option value=""><?php echo esc_html( $args['all_items_label'] ); ?>
			<?php foreach( $args['terms'] as $term ) : ?>
				<option value="<?php echo esc_attr( $term->slug ); ?>" <?php selected( $term->slug, $args['selected_term'] ); ?>><?php echo esc_html( $term->name ); ?></option>
			<?php endforeach; ?>
		</select>
	<?php
}