get_post_type() in in_array doesn't work for some reason

Question

I am trying to create some function for metaboxes and some reason i can't get get_post_type to work in in_array.

Everything else seems to work in testing but in_array nope.

This is the function that i have

$metabox = array(
    'metabox_one' => array(
      'title' => 'First',
      'screen' => array( 'post' )
    ),
    'metabox_two' => array(
      'title' => 'Second',
      'screen' => array( 'post', 'page')
    )
 );

So for each of those keys in array i want to check screen value and if it's in that array to display metabox.

 function call_vivid_framework_metaboxClass() { 
    $post_type = get_post_type();
    if( isset($metabox) ) {
        foreach ( $metabox as $key => $value ) {
            if ( in_array( $post_type, $value['screen'] )) { 
                new vivid_framework_metaboxClass( $key, $value );
            }
        }
    }
}
add_action( 'load-post.php', 'call_vivid_framework_metaboxClass' );
add_action( 'load-post-new.php', 'call_vivid_framework_metaboxClass' );

And this is when it fails and basically don't display any metabox as it doesn't exist in the array.

When i try to print $value['screen'] i get an array

[0] => post,
[1] => page

When i try to print $post_type on a new page i get an page but still it fails in_array

When i try to manually set an array instead $value['screen'] as:

$screen = array( 'post', 'page');

It fails again.

And when i try to manually set post type in in_array than it works as:

  in_array('page', $value['screen'])

It loads metabox within that $value array.

The only thing that comes to my min is that my function hook is fired before get_post_type() so it doesn't catch the value of post type.

For the class i used and example from WordPress codex page https://codex.wordpress.org/Function_Reference/add_meta_box#Class

Any ideas or suggestion how to get it to work ?

Answer 1

You should use add_meta_boxes to add metaboxes.

This hook fires only the appropriate page and also pass as argumument the current post type, so you can use it instead retrieving it with get_post_type().

Sample code:

function call_vivid_framework_metaboxClass( $post_type ) { 

    // if the metabox var is set outside the function, you should
    // declare it as global
    global $metabox;

    if( ! isset( $metabox ) || ! is_array( $metabox ) ) {
      return;
    }

    foreach ( $metabox as $key => $value ) {
      if (
        isset( $value['screen'] )
        && in_array( $post_type, $value['screen'], true )
      ) { 
         new vivid_framework_metaboxClass( $key, $value );
      }
   }
}

add_action( 'add_meta_boxes', 'call_vivid_framework_metaboxClass' );

Note that I added a check for isset( $value['screen'] ) because you should always check a variable is defined before to use it.