Inject flag service into FlagResetForm

I should have done it like this the first time:)

This looks the same as the docs I found, but I've not yet seen an explanation of how it works

I can give a short chain of logic.

1) FlagResetForm is build in a factory.
2) FlagResetForm::create() is called by the factory to determine the parameters used in preparing the call to " new FlagResetForm(....)"
3) FlagResetForm::__construct is called after which $this->flagService is populated.

FormBase implements and overrides a method "create()" as part of it contract to implement \Drupal\Core\DependencyInjection\ContainerInjectionInterface
and the documentation in there says all this in more formal language..

My argument would be better if I could put my finger on the exact factory... what I do know is that this is not a symfony convention ... so it has to exist as somewhere in the logic glueing Drupal8 onto on of it.

I hope this helps.

I will get to the integration testing sometime this week....

Ah your understanding is correct, but the name for the service in the flag.services.yml file is 'flag'
and that is what I had to plumb into FlagResetForm::create().

PS

Just to fill in something I did not know when I wrote #4 When I say factory ... well in this case
it looks like the routing of all forms go through \Drupal\Core\Controller\FormController.
The first line of FormController::getContentResult extracts the class from the _form parameter in the routing file.


public function getContentResult(Request $request, RouteMatchInterface $route_match) {
$form_arg = $this->getFormArgument($route_match);


I hope I am not labouring the point, but it is the order of the parameters, not the name,
that ties the services collected in the create function to the parameters passed into the constructor.

the book module has a more complex example.

  /**
   * Constructs a BookController object.
   *
   * @param \Drupal\book\BookManagerInterface $bookManager
   *   The book manager.
   * @param \Drupal\book\BookExport $bookExport
   *   The book export service.
   * @param \Drupal\Core\Render\RendererInterface $renderer
   *   The renderer.
   */
  public function __construct(BookManagerInterface $bookManager, BookExport $bookExport, RendererInterface $renderer) {
    $this->bookManager = $bookManager;
    $this->bookExport = $bookExport;
    $this->renderer = $renderer;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static(
      $container->get('book.manager'),
      $container->get('book.export'),
      $container->get('renderer')
    );
  }

Follow up has been created..