ViewsFormMainForm::buildForm

public ViewsFormMainForm::buildForm(array $form, FormStateInterface $form_state, ViewExecutable $view = NULL, $output = [])

public function buildForm(array $form, FormStateInterface $form_state, ViewExecutable $view = NULL, $output = []) {
  $form['#prefix'] = '<div class="views-form">';
  $form['#suffix'] = '</div>';

  $form['#pre_render'][] = 'views_pre_render_views_form_views_form';

  // Add the output markup to the form array so that it's included when the form
  // array is passed to the theme function.
  $form['output'] = $output;
  // This way any additional form elements will go before the view
  // (below the exposed widgets).
  $form['output']['#weight'] = 50;

  $form['actions'] = array(
    '#type' => 'actions',
  );
  $form['actions']['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Save'),
  );

  $substitutions = array();
  foreach ($view->field as $field_name => $field) {
    $form_element_name = $field_name;
    if (method_exists($field, 'form_element_name')) {
      $form_element_name = $field->form_element_name();
    }
    $method_form_element_row_id_exists = FALSE;
    if (method_exists($field, 'form_element_row_id')) {
      $method_form_element_row_id_exists = TRUE;
    }

    // If the field provides a views form, allow it to modify the $form array.
    $has_form = FALSE;
    if (property_exists($field, 'views_form_callback')) {
      $callback = $field->views_form_callback;
      $callback($view, $field, $form, $form_state);
      $has_form = TRUE;
    }
    elseif (method_exists($field, 'viewsForm')) {
      $field->viewsForm($form, $form_state);
      $has_form = TRUE;
    }

    // Build the substitutions array for use in the theme function.
    if ($has_form) {
      foreach ($view->result as $row_id => $row) {
        if ($method_form_element_row_id_exists) {
          $form_element_row_id = $field->form_element_row_id($row_id);
        }
        else {
          $form_element_row_id = $row_id;
        }

        $substitutions[] = array(
          'placeholder' => '<!--form-item-' . $form_element_name . '--' . $form_element_row_id . '-->',
          'field_name' => $form_element_name,
          'row_id' => $form_element_row_id,
        );
      }
    }
  }

  // Give the area handlers a chance to extend the form.
  $area_handlers = array_merge(array_values($view->header), array_values($view->footer));
  $empty = empty($view->result);
  foreach ($area_handlers as $area) {
    if (method_exists($area, 'viewsForm') && !$area->viewsFormEmpty($empty)) {
      $area->viewsForm($form, $form_state);
    }
  }

  $form['#substitutions'] = array(
    '#type' => 'value',
    '#value' => $substitutions,
  );

  return $form;
}