Score:0

Drupal

hook_form_alter() to add placeholder to a text field via custom module

jozi

9/28/23, 8:03 AM

It should be very straightforward and yet, I can't identify the reason why this doesn't add a placeholder to a field in a form:

function posts_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  if ($form_id == "node_post_form" || $form_id == "node_post_edit_form") {
    $form['field_post_subject']['#attributes']['placeholder'] = t("blah");
    dpm($form['field_post_subject']);
  }
}

This confirms that the key placeholder is being set:

The hook_form_alter() works as expected for other things I need to change, except the placeholder. I looked everywhere and it's always the same solution so I'm wondering what I'm missing?

0 + 0

Patrick Kenny

9/28/23, 8:06 AM

Did you rebuild the cache? Also, check your theme template and any preprocessing functions; you may be removing or ignoring the placeholder down the line.

jozi

9/28/23, 8:18 AM

Thanks @PatrickKenny. Yes I did rebuild it + tried with other themes including Bartik. I also tried with other forms but with no luck so far.

Patrick Kenny

9/28/23, 9:34 AM

What type of field is it?

leymannx

9/28/23, 9:58 AM

It looks like you set the placeholder on a `'#type' => 'container'` element. You need to go into the `widget`.

jozi

9/28/23, 10:40 PM

Thanks for your guidance @leymannx - the solution 4uk4 suggested worked

jozi

9/28/23, 10:40 PM

It's a simple plain text field @PatrickKenny

Score:2

Drupal

4uk4

9/28/23, 10:03 AM

You are now setting the placeholder attribute to a container, which should be visible in the source HTML, but doesn't have any effect on the form.

You need to add the placeholder to a form element. You find at least one, for multi-value or multi-property fields multiple, inside the widget key (in your debug output a children of the container).

Text fields have already a configurable option for placeholders. If you need to overwrite it dynamically you have to look for the form element and set a new #placeholder.

This is the form element you are looking for:

StringTextfieldWidget::formElement

$element['value'] = $element + [
  '#type' => 'textfield',
  '#default_value' => $items[$delta]->value ?? NULL,
  '#size' => $this->getSetting('size'),
  '#placeholder' => $this->getSetting('placeholder'),
  '#maxlength' => $this->getFieldSetting('max_length'),
  '#attributes' => ['class' => ['js-text-full', 'text-full']],
];

0 + 0

jozi

9/28/23, 10:38 PM

Thanks so much for your complete response! For future references, `$form['field_name']['widget'][0]['value']['#placeholder']` is where the placeholder is set.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: hook_form_alter() to add placeholder to a text field via custom module

TH: hook_form_alter() เพื่อเพิ่มตัวยึดตำแหน่งในช่องข้อความผ่านโมดูลที่กำหนดเอง

RO: hook_form_alter() pentru a adăuga substituent la un câmp de text prin modul personalizat

RU: hook_form_alter() для добавления заполнителя в текстовое поле через пользовательский модуль

VI: hook_form_alter() để thêm trình giữ chỗ vào trường văn bản thông qua mô-đun tùy chỉnh

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