private function show_single_field( $items, $field ) {
		$key    = null;
		$values = array();

		foreach ( $items as $item ) {
			$item = (object) $item;

			if ( null === $key ) {
				$key = $this->find_item_key( $item, $field );
			}

			if ( 'json' === $this->args['format'] ) {
				$values[] = $item->$key;
			} else {
				\WP_CLI::print_value(
					$item->$key,
					array(
						'format' => $this->args['format'],
					)
				);
			}
		}

		if ( 'json' === $this->args['format'] ) {
			echo json_encode( $values );
		}
	}