--- /dev/null
+<?php
+
+namespace Drupal\workspaces;
+
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Render\Element;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+use Drupal\views\Form\ViewsExposedForm;
+use Drupal\workspaces\Form\WorkspaceFormInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Defines a class for reacting to form operations.
+ *
+ * @internal
+ */
+class FormOperations implements ContainerInjectionInterface {
+
+ /**
+ * The workspace manager service.
+ *
+ * @var \Drupal\workspaces\WorkspaceManagerInterface
+ */
+ protected $workspaceManager;
+
+ /**
+ * Constructs a new FormOperations instance.
+ *
+ * @param \Drupal\workspaces\WorkspaceManagerInterface $workspace_manager
+ * The workspace manager service.
+ */
+ public function __construct(WorkspaceManagerInterface $workspace_manager) {
+ $this->workspaceManager = $workspace_manager;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function create(ContainerInterface $container) {
+ return new static(
+ $container->get('workspaces.manager')
+ );
+ }
+
+ /**
+ * Alters forms to disallow editing in non-default workspaces.
+ *
+ * @param array $form
+ * An associative array containing the structure of the form.
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
+ * The current state of the form.
+ * @param string $form_id
+ * The form ID.
+ *
+ * @see hook_form_alter()
+ */
+ public function formAlter(array &$form, FormStateInterface $form_state, $form_id) {
+ // No alterations are needed in the default workspace.
+ if ($this->workspaceManager->getActiveWorkspace()->isDefaultWorkspace()) {
+ return;
+ }
+
+ // Add an additional validation step for every form if we are in a
+ // non-default workspace.
+ $this->addWorkspaceValidation($form);
+
+ // If a form has already been marked as safe or not to submit in a
+ // non-default workspace, we don't have anything else to do.
+ if ($form_state->has('workspace_safe')) {
+ return;
+ }
+
+ // No forms are safe to submit in a non-default workspace by default, except
+ // for the whitelisted ones defined below.
+ $workspace_safe = FALSE;
+
+ // Whitelist a few forms that we know are safe to submit.
+ $form_object = $form_state->getFormObject();
+ $is_workspace_form = $form_object instanceof WorkspaceFormInterface;
+ $is_search_form = in_array($form_object->getFormId(), ['search_block_form', 'search_form'], TRUE);
+ $is_views_exposed_form = $form_object instanceof ViewsExposedForm;
+ if ($is_workspace_form || $is_search_form || $is_views_exposed_form) {
+ $workspace_safe = TRUE;
+ }
+
+ $form_state->set('workspace_safe', $workspace_safe);
+ }
+
+ /**
+ * Adds our validation handler recursively on each element of a form.
+ *
+ * @param array &$element
+ * An associative array containing the structure of the form.
+ */
+ protected function addWorkspaceValidation(array &$element) {
+ // Recurse through all children and add our validation handler if needed.
+ foreach (Element::children($element) as $key) {
+ if (isset($element[$key]) && $element[$key]) {
+ $this->addWorkspaceValidation($element[$key]);
+ }
+ }
+
+ if (isset($element['#validate'])) {
+ $element['#validate'][] = [get_called_class(), 'validateDefaultWorkspace'];
+ }
+ }
+
+ /**
+ * Validation handler which sets a validation error for all unsupported forms.
+ */
+ public static function validateDefaultWorkspace(array &$form, FormStateInterface $form_state) {
+ if ($form_state->get('workspace_safe') !== TRUE) {
+ $form_state->setError($form, new TranslatableMarkup('This form can only be submitted in the default workspace.'));
+ }
+ }
+
+}