How to add html tag in a form element?

Question

How to add html tag in a form element drupal 8?

$form['buttons']['submit'] = [
  '#type' => 'submit',
  '#value' => T('Send'),
  '#prefix' => '<div class="modal-footer">',
  '#suffix' => '<button type="button" class="btn btn-sm btn-default" data-dismiss="modal">' . $this->t('Close') . '</button></div>',      
  '#attributes' => [
    'class' => ['btn-success'],
  ]
];

I try to add allowed_tags:

$form['buttons']['submit'] = [
  '#type' => 'submit',
  '#value' => T('Send'),
  '#prefix' => '<div class="modal-footer">',
  '#suffix' => '<button type="button" class="btn btn-sm btn-default" data-dismiss="modal">' . $this->t('Close') . '</button></div>',
  '#allowed_tags' => ['button'],
  '#attributes' => [
    'class' => ['btn-success'],
  ]
];

OR

$form['buttons']['#allowed_tags'] = ['button'];
$form['#allowed_tags'] = ['button'];

Not working... Help me please!

Answer 1

I can't tell which element is giving you trouble.

For the div, instead of prefix/suffix you can create a container element:

$form['submit_container'] = array(
  '#type' => 'container',
  '#attributes' => array(
    'class' => ['modal-footer'],
  )
);

And then you can put a submit input inside of that:

$form['submit_container']['submit'] = array(
  '#type' => 'submit',
  '#value' => $this->t('Submit'),
  '#attributes' => array(
    'class' => ['btn', 'btn-sm', 'btn-default'],
    'data-dismiss' => 'modal',
  )
);

If you need a button type='button' just to fire Javascript and not submit the form, that is somewhat problematic, it seems. One method is to override the button template.

Type inline_template may be the best bet:

$form['submit_container']['button'] = array(
  '#type' => 'inline_template',
  '#template' => '<button type="button" class="btn btn-sm btn-default" data-dismiss="modal" onclick="closeButton()">Close</button>',
);

Change a normal submit 'input' type to 'button' type with button tag

Answer 2

If you are looking to add a custom HTML tag use the new type in the form api html_tag, here's an example from the form API documentation :

$build['hello'] = [
  '#type' => 'html_tag',
  '#tag' => 'p',
  '#value' => $this->t('Hello World'),
];