Remove the possibility to add field with machine name id

Revert issue summary changes

The validation is limited only for meili search backend (tested with the db plugin) and it works. So you can not change the machine name of the field to id if the backed is meili, but can change and save if the backend is anything else, so marking it as RTBC.

The error below appears when:

1. Create an index or edit an index
2. Select "- No server -" from server options
3. Save the index
4. Visit /admin/config/search/search-api/index/{index_name}/fields

Error: Call to a member function getBackend() on null in search_api_meilisearch_form_search_api_index_fields_alter() (line 34 of modules/contrib/search_api_meilisearch/search_api_meilisearch.module).
search_api_meilisearch_form_search_api_index_fields_alter(Array, Object, 'search_api_index_fields') (Line: 562)
Drupal\Core\Extension\ModuleHandler->alter('form', Array, Object, 'search_api_index_fields') (Line: 840)
Drupal\Core\Form\FormBuilder->prepareForm('search_api_index_fields', Array, Object) (Line: 284)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 73)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 580)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 169)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 81)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 718)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

Also form validation is not enough as the following is possible:

1. Detach the index from meilisearch server (either to " - No server - " or other backend types) in the edit index form
2. Save and then edit the fields and set the machine name as "id"
3. Save and then reattach the index to meilisearch

It should not be possible to have an index attached to meilisearch with an "id" field present. But perhaps we are overcomplicating things and should use search_api_ prefix (as these are reserved and user is not allowed to set them on any indexes) for primary key such as search_api_meilisearch_id or search_api_document_id. With 📌 Remove entity id mapping config Fixed close to finish a full reindex of meilisearch indexes will be required anyway...

@bcizej I like the idea you proposed of using search_api_ prefix. This is probably the most elegant way of fixing this. Will look in to it.

Changed the logic to what @bcizej suggested, now the primary index id is search_api_document_id. Also setting the primary id at index creation prevents an error of multiple id when meilisearch is trying to guess what the primary id is at creation.

Merged, thanks.

Automatically closed - issue fixed for 2 weeks with no activity.