I’d like to retrieve the meta_key names, (and values), for all wp_usermeta records for 1 specific user.
While I can do this by querying the database with the proper SQL I can’t get it with the get_user_meta function call.

Using $wpdb->get_result

$all_user_meta = $wpdb->get_results ( "SELECT * FROM wp_usermeta WHERE user_id = $user_id " );  

if ( !empty($all_user_meta) )
{

     $cnt = 0 ;      
     $idx = -1 ;      
     foreach ( $all_user_meta as $one_meta )
     {              

           $meta_key = $one_meta->meta_key ;
           echo('Meta Key: '.$meta_key.'<br/>');

           THIS WORKS !!             

     }
}

   Using WordPress function Call 


$user_meta_array = get_user_meta($user_id) ;
foreach($user_meta_array as $user_meta)
{
    $meta_key = $user_meta->meta_key ;
    echo('Meta Key: '.$meta_key.'<br/>');

       THIS DOES NOT WORK !!
       The loop does execute the proper number of times

}