Wordpress meta box not saving and updating - wordpress

Question

function wporg_add_custom_box(){
$screens = ['product', 'wporg_cpt'];
foreach ($screens as $screen) {
add_meta_box(
'wporg_box_id', // Unique ID
'Select a Authors Name ', // Box title
'wporg_custom_box_html', // Content callback, must be of type callable
$screen // Post type
);
}
}
add_action('edit_form_after_title', 'wporg_add_custom_box');
function wporg_custom_box_html($post){
$value = get_post_meta($post->ID, '_getwriter_id', true);
?>
<select name="book_writer_id" id="book_writer_id" class="postbox">
<?php
$type = 'book_authors'; // your post type
$args=array(
'post_type' => $type,
'post_status' => 'publish',
'posts_per_page' => -1,
'caller_get_posts'=> 1
);
$my_query = null;
$my_query = new WP_Query($args);
if( $my_query->have_posts() ) {
while ($my_query->have_posts()) : $my_query->the_post(); $id = get_the_ID();?>
<option value="<?=$id; ?>" <?php selected($value, $id); ?>><?=the_title(); ?></option>
<?php
endwhile;
}
wp_reset_query(); // Restore global post data stomped by the_post().
?>
</select>
<?php }
function wporg_save_postdata($post_id)
{
if (array_key_exists('book_writer_id', $_POST)) {
update_post_meta(
$post_id,
'_getwriter_id',
$_POST['book_writer_id']
);
}
}
add_action('save_post', 'wporg_save_postdata');

Answer 1

I did not used there save_postdate function that why, it not saving value and updating data
function wporg_add_custom_box(){
$screens = ['product', 'wporg_cpt'];
foreach ($screens as $screen) {
add_meta_box(
'wporg_box_id', // Unique ID
'Select a Authors Name ', // Box title
'wporg_custom_box_html', // Content callback, must be of type callable
$screen // Post type
);
}
}
add_action('edit_form_after_title', 'wporg_add_custom_box');
function wporg_custom_box_html($post)
{
$value = get_post_meta($post->ID, '_getwriter_id', true);
?>
<select name="book_writer_id" id="book_writer_id" class="postbox">
<?php
$type = 'book_authors'; // your post type
$args=array(
'post_type' => $type,
'post_status' => 'publish',
'posts_per_page' => -1,
'caller_get_posts'=> 1
);
$my_query = null;
$my_query = new WP_Query($args);
if( $my_query->have_posts() ) {
while ($my_query->have_posts()) : $my_query->the_post(); $id = get_the_ID();?>
<option value="<?=$id; ?>" <?php selected($value, $id); ?>><?=the_title(); ?></option>
<?php
endwhile;
}
wp_reset_query(); // Restore global post data stomped by the_post().
?>
</select>
<?php
}
function wporg_save_postdata($post_id)
{
if (array_key_exists('book_writer_id', $_POST)) {
update_post_meta(
$post_id,
'_getwriter_id',
$_POST['book_writer_id']
);
}
}
add_action('save_post', 'wporg_save_postdata');