Generate WordPress Post Tittle from ACF Fields - wordpress

Question

I am trying to generate a custom post title from two ACF fields. I have first_name and last_name but it will only generate the last name and does it twice:
/contacts/deere-deere/
Here's my function:
function update_contacts_title( $value, $post_id, $field ) {
$first_name = get_field('first_name', $post_id). ' ' . $value;
$last_name = get_field('last_name', $post_id). ' ' . $value;
$title = $first_name .' - '. $last_name;
$slug = sanitize_title( $title );
$postdata = array(
'ID' => $post_id,
'post_title' => $title,
'post_type' => 'contacts',
'post_name' => $slug
);
wp_update_post( $postdata );
return $value;
}
add_filter('acf/update_value/name=first_name', 'update_contacts_title', 10, 3);
add_filter('acf/update_value/name=last_name', 'update_contacts_title', 10, 3);
If I modify this line down like so, then it will generate the first_name but only once:
/contacts/john/
//Create new title based on ACF Fields
function update_contacts_title( $value, $post_id, $field ) {
$first_name = get_field('first_name', $post_id). ' ' . $value;
$last_name = get_field('last_name', $post_id). ' ' . $value;
//$title = $first_name .' - '. $last_name;
$title = $first_name;
$slug = sanitize_title( $title );
$postdata = array(
'ID' => $post_id,
'post_title' => $title,
'post_type' => 'contacts',
'post_name' => $slug
);
wp_update_post( $postdata );
return $value;
}
add_filter('acf/update_value/name=first_name', 'update_contacts_title', 10, 3);
//add_filter('acf/update_value/name=last_name', 'update_contacts_title', 10, 3);
This is really confusing me as to why it won't recognize both the first name and last name.
Any suggestions would be extremely helpful, thank you all.

Answer 1

You have "first_name" for both the names I believe.
$first_name = get_field('first_name', $post_id). ' ' . $value;
$last_name = get_field('first_name', $post_id). ' ' . $value;

Answer 2

Here's the answer I figured out after I remembered that I have the first_name and last_name in a group, which requires a repeater field in the function:
function update_contacts_title($post_id) {
if( have_rows('contact_info') ):
while( have_rows('contact_info') ): the_row();
$first_name = get_sub_field('first_name', $post_id);
$last_name = get_sub_field('last_name', $post_id);
$title = $first_name . '-' . $last_name;
$slug = sanitize_title( $title );
endwhile;
endif;
$postdata = array(
'ID' => $post_id,
'post_title' => $title,
'post_type' => 'contacts',
'post_name' => $slug
);
wp_update_post( $postdata );
}
add_filter('acf/save_post', 'update_contacts_title', 10, 3);