How to retrieve custom field values and save again as array

Question

I am new to PHP and WordPress.

I have this scenario.
There are 4 custom fields saved in page, named:
_custField1
_custField2
_custField3
_custField4

What I need to do now is to fetch their values and save them in an array and save that array back to page as custom field.

I tried following.

$page_list = get_pages();
 foreach($page_list as $page) {
         $post_id = $page->ID;
         $custField1= get_post_meta( $post_id, '_custField1' );
         $custField2= get_post_meta( $post_id, '_custField2' );
         $custField3= get_post_meta( $post_id, '_custField3' );
         $custField4= get_post_meta( $post_id, '_custField4' );

         $custArray[] = array(
           '_custField1'=>$custField1,
           '_custField2'=>$custField2,
           '_custField3'=>$custField3,
           '_custField4'=>$custField4
          );

         add_post_meta ( $post_id, '_newcust',maybe_serialize($custArray), true );
}
endforeach;
wp_reset_postdata();

It does save as array but each custom field is saved as array themself. While I want to achieve the results now as _newcust['_custField1'] , which I can not.

What I am doing wrong here ?

PS: One more thing, above code crashes the website if there are more than 50 pages, how should I optimize it.

Help will be greatly appreciated.

Answer 1

This is how I would do it...

$page_list = get_pages();
foreach($page_list as $page) {
     $post_id = $page->ID;

     $custArray = array(
       '_custField1'    => get_post_meta( $post_id, '_custField1', true ),
       '_custField2'    => get_post_meta( $post_id, '_custField2', true ),
       '_custField3'    => get_post_meta( $post_id, '_custField3', true ),
       '_custField4'    => get_post_meta( $post_id, '_custField4', true )
      );

     add_post_meta ( $post_id, '_newcust', $custArray, true );
}

The value will be serialized by WordPress if it is an array - see https://codex.wordpress.org/Function_Reference/add_post_meta

Answer 2

you should use get_post_meta( $post_id, '_custField1', true );

make $single parameter true so it will return a single value.