Форма с отправкой файла в админке

mymodule.admin_form:
  path: '/admin/config/mymodule/form'
  defaults:
    _form: '\Drupal\mymodule\Form\AdminForm'
    _title: 'MyModule Admin Form'
  requirements:
    _permission: 'administer site configuration'

namespace Drupal\mymodule\Form;
 
use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
 
class AdminForm extends FormBase {
 
  public function getFormId() {
    return 'mymodule_admin_form';
  }
 
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['file'] = [
      '#type' => 'managed_file',
      '#title' => $this->t('Upload file'),
      '#description' => $this->t('Upload a file to be processed.'),
      '#upload_location' => 'public://mymodule/files',
    ];
 
    $form['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Save'),
    ];
 
    return $form;
  }
 
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $file = $form_state->getValue('file');
    // Process the uploaded file here.
  }
}