Remove an item from $form_state in an ajax callback

Question

I'm using this form api example: AjaxAddMore. I want to add a "remove button" for each indiviaul element, in order to remove an item but not the latest. Thouse are my changes:

...
  $form['names_fieldset'] = [
      '#type' => 'fieldset',
      '#title' => $this->t('People coming to picnic'),
      '#prefix' => '<div id="names-fieldset-wrapper">',
      '#suffix' => '</div>',
      '#attributes' => array('class'=>array('container-inline')),
    ];

    for ($i = 0; $i < $num_names; $i++) {

      $form['names_fieldset']['fields'][$i] = [
        '#type' => 'fieldset',
        '#name' => 'id_'.$i
      ];

      $form['names_fieldset']['fields'][$i]['ids'] = [
        '#type' => 'textfield',
        '#title' => $this->t('ID'),
        '#default_value' => $i,
        '#name' => 'id_'.$i
      ];

      $form['names_fieldset']['fields'][$i]['name'] = [
        '#type' => 'textfield',
        '#title' => $this->t('Name')
      ];

      $form['names_fieldset']['fields'][$i]['remove'] = [
        '#type' => 'submit',
        '#name' => 'remove_'.$i,
        '#value' => $this->t('Remove this'),
        '#submit' => ['::removethisCallback'],
        '#ajax' => [
          'callback' => '::addmoreCallback',
          'wrapper' => 'names-fieldset-wrapper',
        ],
      ];
    }
....

It works good and I can add several records. But I can't remove an item other than the latest one. This is my callback function where I've tried to unset the item I want to remove:

public function removethisCallback(array &$form, FormStateInterface $form_state) {
    $button_clicked = $form_state->getTriggeringElement()['#name'];
    $id = substr($button_clicked,7);
    $values = $form_state->getValue(['names_fieldset']);
    unset($values[$id]);
    $form_state->setValues(['names_fieldset'], array_values($values));  

    $name_field = $form_state->get('num_names');
    if ($name_field > 1) {
        $remove_button = $name_field - 1;
        $form_state->set('num_names', $remove_button);
    }   
    $form_state->setRebuild();
}

But It doesn't work. How could I remove or update an item from $form_state?

Answer 1

$form_state->setValues(['names_fieldset'], array_values($values));

setValues(array $values) only has 1 parameter

For 2 params, you need to use setValue($key, $value) without the "s"

$form_state->setValue('name', array_values($values));  

---

Alternatively, you could do

$values = $form_state->getValues();
$values['name'] = array_values($values);
$form_state->setValues($values);

Answer 2

I have same problem, and I think I have a working solution (D9).

public function buildForm(array $form, FormStateInterface $form_state): array {
  // $form_state contains all values. Add a new item for init.
  $values = $form_state->getValues();

  if (!isset($values['persons'])) {
    $values['persons'][] = [
      'name' => '',
      'birthdate' => '',
      'btn_text' => 'remove person',
    ];
  }
}

An example from the $form build:

foreach ($values['persons'] as $k => $v) {
  $form['persons'][$k]['name'] = [
    '#type' => 'textfield',
    '#title' => 'Person name',
  ];
}

Remove btn. #indx is the person id param.

$form['persons'][$k]['remove_person'] = [
  '#type' => 'submit',
  '#value' => 'remove person',
  '#submit' => ['::removePerson'],
  '#name' => 'reove_person_' . $k,
  '#indx' => 'indx' . $k,
  '#ajax' => [
    'callback' => '::personCallback',
    'wrapper' => 'persons',
  ],
  '#suffix' => '<hr>',
];

Remove person callback get the person index (#indx), remove the item, and rebuild the $form_state:

public function removePerson(array &$form, FormStateInterface $form_state): void {
  $values = $form_state->getValues();
  $element = $form_state->getTriggeringElement();

  if (!isset($element['#indx'])) {
    return;
  }

  $i = preg_replace('~\D~', '', $element['#indx']);

  if (isset($values['persons'][$i])) {
    unset($values['persons'][$i]);
  }

  $form_state->setValues($values);
  $form_state->setRebuild();
}

person callback rebuild the form:

public function personCallback(array &$form, FormStateInterface $form_state): array {
  return $form['persons'];
}