Form submit results in “Too many redirects” error for anonymous users

Question

I have a custom route on my site at /search. This page has a couple of forms on it (defined with FormBase).

When I am logged in, the form appears to work.

When I am anonymous, many many requests occur when I submit and causes a "too many redirects" error in the browser.

Here is my routing.yml

mymodule.search:
 path: '/search'
 defaults:
   _title_callback: 'Drupal\mymodule\Controller\SearchPage::title'
   _controller: 'Drupal\mymodule\Controller\SearchPage::build'
 requirements:
   _permission: 'access content'

Here is one of the forms:

<?php

namespace Drupal\mymodule\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpFoundation\RequestStack;
use Drupal\Component\Utility\Xss;
use Drupal\Component\Utility\Unicode;

/**
 * Class KeywordForm.
 *
 * @package Drupal\mymodule\Form
 */
class KeywordForm extends FormBase {

  /**
   * Symfony\Component\HttpFoundation\RequestStack definition.
   *
   * @var \Symfony\Component\HttpFoundation\RequestStack
   */
  protected $requestStack;

  /**
   * Constructor for our class.
   */
  public function __construct(RequestStack $request_stack) {
    $this->requestStack = $request_stack;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static(
      $container->get('request_stack')
    );
  }

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'iana_keyword_form';
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $keywords = Xss::filter($this->requestStack->getCurrentRequest()->get('keywords'));
    $site_ids = $this->requestStack->getCurrentRequest()->get('site_id');
    $sort_by = $this->requestStack->getCurrentRequest()->get('sort_by');
    $sort_order = $this->requestStack->getCurrentRequest()->get('sort_order');

    $form['#attributes']['class'][] = 'search-result__form';

    if (!is_array($site_ids)) {
      $site_ids = [];
    }

    $form['keywords'] = [
      '#type' => 'textfield',
      '#cache' => ['contexts' => ['url.query_args:keywords']],
      '#default_value' => Unicode::strlen($keywords) ? $keywords : '',
      '#prefix' => '<div class="search-box__input js-search-input">',
      '#suffix' => '</div>',
      '#attributes' => [
        'placeholder' => Unicode::strlen($keywords) ? $keywords : t('Search for...'),
      ],
    ];

    $form['site_id'] = [
      '#type' => 'hidden',
      '#value' => $site_ids,
    ];

    $form['sort_by'] = [
      '#type' => 'hidden',
      '#value' => $sort_by,
    ];

    $form['sort_order'] = [
      '#type' => 'hidden',
      '#value' => $sort_order,
    ];

    $form['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Search'),
      '#attributes' => [
        'class' => [
          'search-box__button',
        ],
        'data-twig-suggestion' => 'search_results_submit',
      ],
    ];

    $form['#cache']['contexts'][] = 'session';
    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $form_state->setRedirect(
      'mymodule.search',
      [
        'keywords' => $form_state->getValue('keywords'),
        'site_id' => $form_state->getValue('site_id'),
        'sort_by' => $form_state->getValue('sort_by'),
        'sort_order' => $form_state->getValue('sort_order'),
      ],
      [
        'query' => [
          'keywords' => $form_state->getValue('keywords'),
          'site_id' => $form_state->getValue('site_id'),
          'sort_by' => $form_state->getValue('sort_by'),
          'sort_order' => $form_state->getValue('sort_order'),
        ],
      ]
    );
  }

}

It looks like at some point, I hit this bit of code in the FormBuilder class:

// If the form returns a response, skip subsequent page construction by
// throwing an exception.
// @see Drupal\Core\EventSubscriber\EnforcedFormResponseSubscriber
//
// @todo Exceptions should not be used for code flow control. However, the
//   Form API does not integrate with the HTTP Kernel based architecture of
//   Drupal 8. In order to resolve this issue properly it is necessary to
//   completely separate form submission from rendering.
//   @see https://www.drupal.org/node/2367555
if ($response instanceof Response) {
  throw new EnforcedResponseException($response);
}

Here is what Google Chrome devtools window shows for network activity:

What is going on here, and how can I fix this? I need the values attached to the URL when the form is submitted.

All of the Forms are displayed on the sidebar and header as blocks injecting those forms. Only 3 forms exist, keyword and a simple checkbox filter.

For the life of me, I can't see what is wrong.

The cache_render table is filling up with various search URLs, it should not, though no matter what I set #cache to, it does.

Answer 1

Thanks to 4k4 and some folks in IRC, it turns out that the culprit here is the Redirect module.

I was able to solve this by:

• Disable Enforce clean and canonical URLs. in Redirect
• Add /search and /search* to URLs to ignore in Redirect

After setting that and clearing cache, anonymous users were no longer stuck in an endless redirect loop when using search forms.