Fatal error: Uncaught Error: Call to undefined function get_userdata()

Question

I am getting this error when I call this method $query->the_post();. I am trying to get the post id to get the post meta data. Accessing the $post->ID from global post return the current page id, but I need the post id for searching purpose.

You can see the error as image here

function search_form_submit(){

$task_name  = isset($_GET['taskname']) ? $_GET['taskname'] : '';
$meta_key = 'wp_tasks';

$args = array(
                    'post_type' => 'tasks',
                    'post_status' => 'publish',
                    'posts_per_page' => 5,
                    'meta_query' => array(
                        array(
                            'key' => $meta_key,
            'value' => $task_name,
                            'compare' => 'LIKE',
                        ),
                    ),
                );


$query = new WP_Query($args);
global $post;

if($query->have_posts()){

    $query->the_post();

    $data = get_post_meta($post->ID,$meta_key,true);
     }
 }

 $tasks_obj = new tasks();

  if($_SERVER['REQUEST_METHOD'] == 'GET') {
  $tasks_obj->search_form_submit();
 }

Answer 1

Generally, forms should be handled on init action or later (mainly in a plugin file, maybe in the theme's functions.php file, never in a tempalte file), so you can have access to WP functions.

add_action( 'init', 'search_form_submit' );
function search_form_submit(){

    $task_name  = isset($_GET['taskname']) ? $_GET['taskname'] : '';
    $meta_key = 'wp_tasks';

    $args = array(
                        'post_type' => 'tasks',
                        'post_status' => 'publish',
                        'posts_per_page' => 5,
                        'meta_query' => array(
                            array(
                                'key' => $meta_key,
                'value' => $task_name,
                                'compare' => 'LIKE',
                            ),
                        ),
                    );


    $query = new WP_Query($args);

    if($query->have_posts()){

        $query->the_post();

        $data = get_post_meta(get_the_ID(),$meta_key,true);
         }
     }

     $tasks_obj = new tasks();

     if($_SERVER['REQUEST_METHOD'] == 'GET') {
      $tasks_obj->search_form_submit();
     }

}