wordpress-save-file.php

<?php
/**
 * Saves the file from file input and return attachment ID
 * @param string $input_name Name of file input
 * @param bool $return_id Whether
 * @return int|string|WP_Error ID of the attachment or a WP_Error object on failure.
 */
function shramee_upload_media( $input_name, $return_id = false ) {
	if ( ! function_exists( 'media_handle_upload' ) ) {
		require_once ABSPATH . 'wp-admin/includes/image.php';
		require_once ABSPATH . 'wp-admin/includes/file.php';
		require_once ABSPATH . 'wp-admin/includes/media.php';
	}

	$media_id = media_handle_upload( $input_name, 0 );
	if ( $return_id ) {
		return $media_id;
	}
	return wp_get_attachment_url( $media_id );
}