^^&&^^

Edit File: class-kkart-admin-exporters.php

<?php
/**
 * Init Kkart data exporters.
 *
 * @package     Kkart\Admin
 * @version     3.1.0
 */

use Automattic\Jetpack\Constants;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * KKART_Admin_Exporters Class.
 */
class KKART_Admin_Exporters {

/**
	 * Array of exporter IDs.
	 *
	 * @var string[]
	 */
	protected $exporters = array();

/**
	 * Constructor.
	 */
	public function __construct() {
		if ( ! $this->export_allowed() ) {
			return;
		}

add_action( 'admin_menu', array( $this, 'add_to_menus' ) );
		add_action( 'admin_head', array( $this, 'hide_from_menus' ) );
		add_action( 'admin_enqueue_scripts', array( $this, 'admin_scripts' ) );
		add_action( 'admin_init', array( $this, 'download_export_file' ) );
		add_action( 'wp_ajax_kkart_do_ajax_product_export', array( $this, 'do_ajax_product_export' ) );

// Register Kkart exporters.
		$this->exporters['product_exporter'] = array(
			'menu'       => 'edit.php?post_type=product',
			'name'       => __( 'Product Export', 'kkart' ),
			'capability' => 'export',
			'callback'   => array( $this, 'product_exporter' ),
		);
	}

/**
	 * Return true if Kkart export is allowed for current user, false otherwise.
	 *
	 * @return bool Whether current user can perform export.
	 */
	protected function export_allowed() {
		return current_user_can( 'edit_products' ) && current_user_can( 'export' );
	}

/**
	 * Add menu items for our custom exporters.
	 */
	public function add_to_menus() {
		foreach ( $this->exporters as $id => $exporter ) {
			add_submenu_page( $exporter['menu'], $exporter['name'], $exporter['name'], $exporter['capability'], $id, $exporter['callback'] );
		}
	}

/**
	 * Hide menu items from view so the pages exist, but the menu items do not.
	 */
	public function hide_from_menus() {
		global $submenu;

foreach ( $this->exporters as $id => $exporter ) {
			if ( isset( $submenu[ $exporter['menu'] ] ) ) {
				foreach ( $submenu[ $exporter['menu'] ] as $key => $menu ) {
					if ( $id === $menu[2] ) {
						unset( $submenu[ $exporter['menu'] ][ $key ] );
					}
				}
			}
		}
	}

/**
	 * Enqueue scripts.
	 */
	public function admin_scripts() {
		$suffix  = Constants::is_true( 'SCRIPT_DEBUG' ) ? '' : '.min';
		$version = Constants::get_constant( 'KKART_VERSION' );
		wp_register_script( 'kkart-product-export', KKART()->plugin_url() . '/assets/js/admin/kkart-product-export' . $suffix . '.js', array( 'jquery' ), $version );
		wp_localize_script(
			'kkart-product-export',
			'kkart_product_export_params',
			array(
				'export_nonce' => wp_create_nonce( 'kkart-product-export' ),
			)
		);
	}

/**
	 * Export page UI.
	 */
	public function product_exporter() {
		include_once KKART_ABSPATH . 'includes/export/class-kkart-product-csv-exporter.php';
		include_once dirname( __FILE__ ) . '/views/html-admin-page-product-export.php';
	}

/**
	 * Serve the generated file.
	 */
	public function download_export_file() {
		if ( isset( $_GET['action'], $_GET['nonce'] ) && wp_verify_nonce( wp_unslash( $_GET['nonce'] ), 'product-csv' ) && 'download_product_csv' === wp_unslash( $_GET['action'] ) ) { // WPCS: input var ok, sanitization ok.
			include_once KKART_ABSPATH . 'includes/export/class-kkart-product-csv-exporter.php';
			$exporter = new KKART_Product_CSV_Exporter();

if ( ! empty( $_GET['filename'] ) ) { // WPCS: input var ok.
				$exporter->set_filename( wp_unslash( $_GET['filename'] ) ); // WPCS: input var ok, sanitization ok.
			}

$exporter->export();
		}
	}

/**
	 * AJAX callback for doing the actual export to the CSV file.
	 */
	public function do_ajax_product_export() {
		check_ajax_referer( 'kkart-product-export', 'security' );

if ( ! $this->export_allowed() ) {
			wp_send_json_error( array( 'message' => __( 'Insufficient privileges to export products.', 'kkart' ) ) );
		}

include_once KKART_ABSPATH . 'includes/export/class-kkart-product-csv-exporter.php';

$step     = isset( $_POST['step'] ) ? absint( $_POST['step'] ) : 1; // WPCS: input var ok, sanitization ok.
		$exporter = new KKART_Product_CSV_Exporter();

if ( ! empty( $_POST['columns'] ) ) { // WPCS: input var ok.
			$exporter->set_column_names( wp_unslash( $_POST['columns'] ) ); // WPCS: input var ok, sanitization ok.
		}

if ( ! empty( $_POST['selected_columns'] ) ) { // WPCS: input var ok.
			$exporter->set_columns_to_export( wp_unslash( $_POST['selected_columns'] ) ); // WPCS: input var ok, sanitization ok.
		}

if ( ! empty( $_POST['export_meta'] ) ) { // WPCS: input var ok.
			$exporter->enable_meta_export( true );
		}

if ( ! empty( $_POST['export_types'] ) ) { // WPCS: input var ok.
			$exporter->set_product_types_to_export( wp_unslash( $_POST['export_types'] ) ); // WPCS: input var ok, sanitization ok.
		}

if ( ! empty( $_POST['export_category'] ) && is_array( $_POST['export_category'] ) ) {// WPCS: input var ok.
			$exporter->set_product_category_to_export( wp_unslash( array_values( $_POST['export_category'] ) ) ); // WPCS: input var ok, sanitization ok.
		}

if ( ! empty( $_POST['filename'] ) ) { // WPCS: input var ok.
			$exporter->set_filename( wp_unslash( $_POST['filename'] ) ); // WPCS: input var ok, sanitization ok.
		}

$exporter->set_page( $step );
		$exporter->generate_file();

$query_args = apply_filters(
			'kkart_export_get_ajax_query_args',
			array(
				'nonce'    => wp_create_nonce( 'product-csv' ),
				'action'   => 'download_product_csv',
				'filename' => $exporter->get_filename(),
			)
		);

if ( 100 === $exporter->get_percent_complete() ) {
			wp_send_json_success(
				array(
					'step'       => 'done',
					'percentage' => 100,
					'url'        => add_query_arg( $query_args, admin_url( 'edit.php?post_type=product&page=product_exporter' ) ),
				)
			);
		} else {
			wp_send_json_success(
				array(
					'step'       => ++$step,
					'percentage' => $exporter->get_percent_complete(),
					'columns'    => $exporter->get_column_names(),
				)
			);
		}
	}
}

new KKART_Admin_Exporters();