I'm working on a drupal page and recently encountered a problem when I couldn't enable comments on a certain content type. Looking for the problem I found that there were no fields for the comments in that content type.

I checked the other content types where comments were enabled without problems and checked which fields were enabled for the comments. I tried to enable the comments in the first content type by adding an existing field for comments, but the comment fields were not available to choose.

Here i attach an image of what it looks like on the drupal (It's in spanish but I hope you can get the context) How the content type looks like without comment fields

This is how it should look like with the comment fields: How the content type looks like with the comment fields

Is there a way to retrieve this fields so comments can be enabled for this content type?

  • Have you tried re-adding them by looking to see if they are listed in Seleccione un campo existente ?
    – No Sssweat
    Nov 23, 2015 at 16:35
  • Yes I tried, as I mentioned in the question, but the comment fields were not available to choose there. Nov 23, 2015 at 16:38

1 Answer 1


Basing on the code for comment_field_extra_fields(), I think that what you are noting can be explained with the comment_subject_field_$type persistent variable being set to a value different from 1. ($type is the machine name of the content type.)

function comment_field_extra_fields() {
  $return = array();

  foreach (node_type_get_types() as $type) {
    if (variable_get('comment_subject_field_' . $type->type, 1) == 1) {
      $return['comment']['comment_node_' . $type->type] = array(
        'form' => array(
          'author' => array(
            'label' => t('Author'),
            'description' => t('Author textfield'),
            'weight' => -2,
          'subject' => array(
            'label' => t('Subject'),
            'description' => t('Subject textfield'),
            'weight' => -1,

  return $return;

comment_form() contains the following code.

  $form['subject'] = array(
    '#type' => 'textfield',
    '#title' => t('Subject'),
    '#maxlength' => 64,
    '#default_value' => $comment->subject,
    '#access' => variable_get('comment_subject_field_' . $node->type, 1) == 1,
    '#weight' => -1,

Only when the 'comment_subject_field_' . $node->type persistent variable is set to 1 the users have access to that form field.

Changing the value of that persistent variable to 1 should restore those form fields you are expecting to see.

  • I'll check it tomorrow and I will tell you if this works. thank you. Nov 23, 2015 at 17:19
  • I confirmed that it was the problem. It was solved by adding variable_set('comment_subject_field_' . $node->type, 1); in the node type template. Nov 24, 2015 at 12:24

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