Saving the value when product is published/updated

cmnq_min_max_quantity.php

<?php
/*
* This function will save the value set to Minimum Quantity and Maximum Quantity options
* into _wc_min_qty_product and _wc_max_qty_product meta keys respectively
*/

function wc_qty_save_product_field( $post_id ) {
	$val_min = trim( get_post_meta( $post_id, '_wc_min_qty_product', true ) );
	$new_min = sanitize_text_field( $_POST['_wc_min_qty_product'] );

	$val_max = trim( get_post_meta( $post_id, '_wc_max_qty_product', true ) );
	$new_max = sanitize_text_field( $_POST['_wc_max_qty_product'] );
	
	if ( $val_min != $new_min ) {
		update_post_meta( $post_id, '_wc_min_qty_product', $new_min );
	}

	if ( $val_max != $new_max ) {
		update_post_meta( $post_id, '_wc_max_qty_product', $new_max );
	}
}
add_action( 'woocommerce_process_product_meta', 'wc_qty_save_product_field' );

?>