custom-filters.md

Custom filters

To use objects of a certain class as parameters you will need two services. One implementing Arachne\EntityLoader\FilterInInterface with arachne.entityLoader.filterIn tag and one implementing Arachne\EntityLoader\FilterOutInterface with arachne.entityLoader.filterOut tag. For both services pass the classes handled by these services as the tag attribute.

services:
    dateTimeFilterIn:
        class: DateTimeFilterIn
        tags:
            - arachne.entityLoader.filterIn
    dateTimeFilterOut:
        class: DateTimeFilterOut
        tags:
            - arachne.entityLoader.filterOut

class DateTimeFilterIn implements \Arachne\EntityLoader\FilterInInterface
{
    public function supports(string $type): bool
    {
        return $type === \DateTime::class;
    }

    public function filterIn($value, string $type)
    {
        if (is_numeric($value)) { // timestamp
            return new \DateTime(date('Y-m-d H:i:s', $value));
        } else { // textual
            return new \DateTime($value);
        }
    }
}

class DateTimeFilterOut implements \Arachne\EntityLoader\FilterOutInterface
{
    public function supports(string $class): bool
    {
        return $class === \DateTime::class;
    }

    public function filterOut($entity)
    {
        // $entity instanceof DateTime
        return $entity->getTimestamp();
    }
}

You could argue that filterIn method should only handle timestamps and not other formats because filterOut always returns a timestamp. The point is that filterOut should always return an identifier from which the object can be recreated. Regardless how you wish to represent the parameter in the URL. You can change the URL representation in router (see the example below).

Presenter

Finally we can use DateTime parameters in presenter:

class FooPresenter extends \Nette\Application\UI\Presenter
{
    public function renderDefault(DateTime $date)
    {
        $this->template->date = $date;
    }
}

Persistent parameters are also supported. Use the @var annotation to specify the class.

Routers

Now what if we want to use different format than timestamp in URL? For example imagine that you don't need the time part in one case when you use a DateTime parameter and want to reptesent the date simply as 'Y-m-d' in the URL. This is supported and it can even be specific to the route in question. The solution uses Route::FILTER_OUT option and an Envelope object.

To use Envelopes you need to use Arachne\EntityLoader\Routing\Route instead of Nette\Application\Routers\Route. Then enable envelopes in config.

arachne.entityLoader:
    envelopes: true

The envelope is a simple class implementing the __toString method. Thanks to that and some magic in the Arachne\EntityLoader\Routing\Route class they won't have any effect on your application other than that you can use them to get the underlying object in Route::FILTER_OUT callbacks:

$router[] = new Route('/<date>', [
    'presenter' => 'Foo',
    'date' => [
        Route::FILTER_OUT => function (\Arachne\EntityLoader\Application\Envelope $value) {
            return $value->getEntity()->format('Y-m-d');
        },
    ],
]);