The WordPress Studio Framework can also be used to extend the Comment metabox with custom fields.

Comment Metabox Framework Arguments

Name	Type	Default	Description
title	string		Title of the comment metabox
data_type	string	serialize	Database save option type (serialize | unserialize)
priority	string	default	The priority within the context where the boxes should show. (high | low | default)
show_restore	bool	false	Flag to display restore button of the comment metabox
theme	string	dark	The theme framework (dark | light)
class	string		Extra CSS classes (space separated) to append to the main framework
defaults	array		Sets all default values from an external array (optional)

Comment Metabox Framework Example

// Check to see if the WPSF class exists
if ( class_exists( 'WPSF' ) ){

  // Set unique slug ID
  $prefix = 'custom_comment_options';

  // Create comment metabox
  WPSF::createCommentMetabox( $prefix, array(
    'title' => 'Custom Comment Options',
  ));

  // Create section
  WPSF::createSection( $prefix, array(
    'fields' => array(
      array(
        'id' => 'example-text',
        'type' => 'text',
        'title' => 'Example Text',
      ),
      array(
        'id' => 'example-textarea',
        'type' => 'textarea',
        'title' => 'Example Textarea',
      ),
      array(
        'id' => 'example-select',
        'type' => 'select',
        'title' => 'Example Select',
        'options' => array(
          'option1' => 'Option One',
          'option2' => 'Option Two',
          'option3' => 'Option Three',
        )
      ),
    )
  ));
}

Extract Option Value (data_type => serialize)

$meta = get_comment_meta( get_comment_ID(), 'custom_comment_options', true );

echo $meta['example-text'];
echo $meta['example-textarea'];

Extract Option Value (data_type => unserialize)

echo get_comment_meta( get_comment_ID(), 'example-text', true );
echo get_comment_meta( get_comment_ID(), 'example-textarea', true );