How to check for content type in hook_form_alter

Question

I see from the api and various posts that I can identify a specific form to change using hook_form_alter, like this: hook_form_FORM_ID_alter()

From experience, I know this can be done in the .theme file along these lines...

function MYTHEME_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  if($form_id == 'node_pm_form' || $form_id == 'FORMIDHERE') {
    $form['actions']['submit']['#value'] = t('Send');
  }

But I have a form that occurs on different node types and I want to change the submit button label based on the node type. I tried renaming the function like this... function MYTHEME_form_alter__NODETYPE and MYTHEME_form_alter__NODETYPE__full

That didn't work. I'm thinking form_alter just doesn't accept node type in the function name, so I need some logic in the code to check for node type and condition results on that. But I don't yet know how to write that.

I forgot to mention: the node edit form ID's in my theme include the content type. But I want to alter the comment edit form based on what node type replying to. And all my comment forms have the same id.

Answer 1

To get the content type on content type forms, you can get the form object, then the node from that, and finally the bundle (content type):

$form_object = $form_state->getFormObject();
$node = $form_object->getEntity()
$content_type = $node->bundle();

When altering a comment form, to get the entity type of the entity the comment is attached to, you have to fetch the commented entity before getting the bundle.

$form_object = $form_state->getFormObject();
$comment = $form_object->getEntity();
$node = $comment->getCommentedEntity();
$content_type = $node->bundle();

So your function would look something like

function HOOK_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
  $comment_form_id = '[ENTER COMMENT FORM ID HERE]';
  if ($form_id == $comment_form_id) {
    $form_object = $form_state->getFormObject();
    $comment = $form_object->getEntity();
    $node = $comment->getCommentedEntity();
    $content_type = $node->bundle();
    if ($content_type == $some_content_type) {
      // Do stuff.
    }
  }
}