Optionally show warning messages when referenced entities are being edited / deleted

Such things would be awesome.

1) The need for warnings vary based on the usage type. Some references are true embeds where awareness is key because the information is embedded in the usage origin. A media item description might be shown immediately. Links in content (linkit) are usually no reason to warn on edit.

2) Agree showing the items individually with label is a great thing as long as the list is not too long.
Also here, some fields need to be excluded. You don't want to warn the user that Paragraphs are deleted when the Host entity is deleted - that's obvious.

> Also here, some fields need to be excluded. You don't want to warn the user that Paragraphs are deleted when the Host entity is deleted - that's obvious.

Then don't track them, which they by default aren't :)

Also don't get why it shouldn't warn on links, those kind of embeds/links are just as problematic when being deleted, e.g. they can be embedded download links to files.

Interesting...

So you think that it's fine to treat them all the same?
Just asking - how about term usage or user (author) usage? Just don't track? At least term usage can be of great value because regular term views only show content.

Maybe some type of references should disallow delete?
(Or maybe we should offer a permission to still delete even if it is used.)

And in case we still allow deletion - we maybe should offer a method to fix broken links. From simply filtering them out when rendering to batch updating the content to remove the reference. What do you think? ;-)

I'm thinking that this isn't about preventing deletion, not for now anyway. It's just a warning, just like we're doing ourself in paragraps_library edit. We already discussed that preventing deletion of used paragraphs_library_item is flawed and doesn't work and needs to be replaced with a warning message.

And yes, users are by default not tracked and we also don't track terms in our sites.

1. +++ b/entity_usage.install
   @@ -111,6 +111,17 @@ function entity_usage_schema() {
   + * Implements hook_install().
   + */
   +function entity_usage_install() {
   +  // On new installs, set the warnings as active by default.
   +  $entity_usage_config = \Drupal::configFactory()->getEditable('entity_usage.settings');
   +  $entity_usage_config->set('show_edit_warning', TRUE);
   +  $entity_usage_config->set('show_delete_warning', TRUE);
   +  $entity_usage_config->save(TRUE);
   +}
   

   Just put that in entity_usage.settings.yml, that is only automatically imported on new installs.

2. +++ b/entity_usage.module
   @@ -67,3 +70,68 @@ function entity_usage_field_storage_config_delete(FieldStorageConfigInterface $f
   +  if ($form_object->getOperation() === 'edit' && $config->get('show_edit_warning')) {
   +    $form['entity_usage_edit_warning'] = [
   +      '#type' => 'container',
   +      '#markup' => t('Modifications on this form will affect all <a href="@usage_url" target="_blank">existing usages</a> of this entity.', [
   +        '@usage_url' => Url::fromRoute('entity_usage.usage_list', [
   +          'entity_type' => $entity->getEntityTypeId(),
   +          'entity_id' => $entity->id(),
   +        ])->toString(),
   +      ]),
   +      '#attributes' => [
   +        'class' => ['messages', 'messages--warning'],
   +      ],
   +      '#weight' => -201,
   +    ];
   

   In #3002571: Multiple warning messages when having untranslatable fields, we switched to #theme status_messages, a bit simpler and doesn't require us to hardcode classes.

3. +++ b/src/Form/EntityUsageSettingsForm.php
   @@ -196,6 +196,29 @@ class EntityUsageSettingsForm extends ConfigFormBase {
   +    $form['generic_settings']['delete_warning_form_classes'] = [
   +      '#type' => 'textarea',
   +      '#title' => $this->t('Form classes for the delete warning'),
   +      '#description' => $this->t("A comma or new-line separated list of Drupal classes where the delete warning message should be shown. If you don't know what this means, you should leave this setting unchanged."),
   +      '#default_value' => implode("\r\n", $config->get('delete_warning_form_classes') ?: ['Drupal\Core\Entity\ContentEntityDeleteForm']),
   +      '#states' => [
   +        'visible' => [
   +          ':input[name="show_delete_warning"]' => ['checked' => TRUE],
   +        ],
   +      ],
   +    ];
   

   not very user friendly but I know it's tricky.

   We do have the operation though (\Drupal\Core\Entity\EntityForm::getOperation) and we cna also check whether an entity type has usage tracking enabled, that might be enough?

3. I see. Anything that has getEntity() also has an operation, but you can't check for the entity type at the same time. Ok I guess, just seems a bit strange to have that UI :)

Working on updating the paragraphs_library module to use this and to remove the custom warning messages from there. But if we would enable it automatically, then this would be also enabled on other entities, which users might not want to see everywhere.
So we need to consider to think about adding an option to enable the messages per entity type.
This way other modules would also benefit, if they only want to enable them, for their entity type.

1. +++ b/config/schema/entity_usage.schema.yml
   @@ -29,3 +29,18 @@ entity_usage.settings:
          type: sequence
          sequence:
            type: string
   +    edit_warning_message_entity_types:
   +      label: Entity types where to show warning on edit form
   +      type: sequence
   +      sequence:
   +        type: string
   +    delete_warning_message_entity_types:
   +      label: Entity types where to show warning on delete form
   +      type: sequence
   +      sequence:
   +        type: string
   +    delete_warning_form_classes:
   +      label: Form classes that should show the delete warning message
   +      type: sequence
   +      sequence:
   +        type: string

   The delete_warning_form_classes setting is not used anymore, so it should be also removed from here.

2. +++ b/src/Form/EntityUsageSettingsForm.php
   @@ -184,6 +184,54 @@ class EntityUsageSettingsForm extends ConfigFormBase {
          }
        }
    
   +    // Edit warning message.
   +    $form['edit_warning_message_entity_types'] = [
   +      '#type' => 'details',
   +      '#open' => FALSE,
   +      '#title' => $this->t('Warning message on edit form'),
   +      '#description' => $this->t('Check which entity types should show a message when being edited with recorded references to it.'),
   +      '#tree' => TRUE,
   +    ];
   +    $form['edit_warning_message_entity_types']['entity_types'] = [
   +      '#type' => 'checkboxes',
   +      '#title' => $this->t('Entity types to show warning on edit form'),
   +      '#options' => $entity_type_options,
   +      '#default_value' => $config->get('edit_warning_message_entity_types') ?: [],
   +      '#required' => FALSE,
   +    ];
   +    // Only allow to opt-in on target entities being tracked.
   +    foreach (array_keys($entity_type_options) as $entity_type_id) {
   +      $form['edit_warning_message_entity_types']['entity_types'][$entity_type_id]['#states'] = [
   +        'enabled' => [
   +          ':input[name="track_enabled_target_entity_types[entity_types][' . $entity_type_id . ']"]' => ['checked' => TRUE],
   +        ]
   +      ];
   +    }
   +
   +    // Delete warning message.
   +    $form['delete_warning_message_entity_types'] = [
   +      '#type' => 'details',
   +      '#open' => FALSE,
   +      '#title' => $this->t('Warning message on delete form'),
   +      '#description' => $this->t('Check which entity types should show a message when being deleted with recorded references to it.'),
   +      '#tree' => TRUE,
   +    ];
   +    $form['delete_warning_message_entity_types']['entity_types'] = [
   +      '#type' => 'checkboxes',
   +      '#title' => $this->t('Entity types to show warning on delete form'),
   +      '#options' => $entity_type_options,
   +      '#default_value' => $config->get('delete_warning_message_entity_types') ?: [],
   +      '#required' => FALSE,
   +    ];
   +    // Only allow to opt-in on target entities being tracked.
   +    foreach (array_keys($entity_type_options) as $entity_type_id) {
   +      $form['delete_warning_message_entity_types']['entity_types'][$entity_type_id]['#states'] = [
   +        'enabled' => [
   +          ':input[name="track_enabled_target_entity_types[entity_types][' . $entity_type_id . ']"]' => ['checked' => TRUE],
   +        ]
   +      ];
   +    }
   

   Here I think 1 foreach should be enough, since the 2 do the same, except for different warning message types. So move the logic from the first into the second foreach and it should be fine.

3. +++ b/tests/src/FunctionalJavascript/IntegrationTest.php
   @@ -3,6 +3,7 @@
    namespace Drupal\Tests\entity_usage\FunctionalJavascript;
    
    use Drupal\Core\Field\FieldStorageDefinitionInterface;
   +use Drupal\Core\Url;
    use Drupal\field\Entity\FieldConfig;
    use Drupal\field\Entity\FieldStorageConfig;
    use Drupal\link\LinkItemInterface;
   @@ -78,6 +79,38 @@ class IntegrationTest extends EntityUsageJavascriptTestBase {
        ];
        $this->assertEquals($expected, $usage);
    
   +    // Open Node 1 edit and delete form and verify that no warning is present.
   +    $this->drupalGet("/node/{$node1->id()}/edit");
   +    $assert_session->pageTextNotContains('Modifications on this form will affect all existing usages of this entity');
   +    $this->drupalGet("/node/{$node1->id()}/delete");
   +    $assert_session->pageTextNotContains('There are recorded usages of this entity');
   +    // Configure nodes to have warning messages on both forms and try again.
   +    $this->drupalGet('/admin/config/entity-usage/settings');
   +    $edit_summary = $assert_session->elementExists('css', '#edit-edit-warning-message-entity-types summary');
   +    $edit_summary->click();
   +    $assert_session->pageTextContains('Entity types to show warning on edit form.');
   +    $page->checkField('edit_warning_message_entity_types[entity_types][node]');
   +    $delete_summary = $assert_session->elementExists('css', '#edit-delete-warning-message-entity-types summary');
   +    $delete_summary->click();
   +    $assert_session->pageTextContains('Entity types to show warning on delete form.');

   The dot at the end of the above sentence is not needed, also in 'Entity types to show warning on edit form.'. One reason that the test would fail.
   Also you need to login with a user with the 'administer entity usage' permission to be able to change the settings.

4. Other test are failing because the test base is changed to the WebDriverTestBase. So revision information is not visible by default, we can't get the status code back now and so on.

Even if those tests are failing, the patch works properly. And those fails are not really connected directly to the new functionality introduced in here.

Addressing all changes from previous comments. Working on fixing tests now. :)

This WebDriver Tests are awesome and tricky at the same time. Fixing all tests I think. :)

The form classes stuff is still "used", it was just removed from the UI, so part of the changes in #20 should be reverted.

Ohh that's true. Adding that logic back. :)