4. Developer corner

Target group: Developers

Writing own variable resolvers

With variables it is possible to add information to a process start which is resolved when submitting a form. This extension ships some variable resolvers already, e.g. for translation or language information.

You can write your own variable resolvers dependent on your needs. Variable resolvers are implemented as PSR-14 event listeners.

The event listener receives the event Brotkrueml\JobRouterBase\Event\ResolveFinisherVariableEvent. It provides the following methods:

getFieldType(): \Brotkrueml\JobRouterBase\Enumeration\FieldType

Changed in version 2.0.0.

Get the field type, like FieldType::Text for text or FieldType::Integer for int. Have a look in the class Brotkrueml\JobRouterBase\Enumeration\FieldType for the available field types.

getValue(): string

Get the current value of the field. One or more variables can be defined inside.

setValue(string $value): void

Set the new value after resolving one or more variables.

getCorrelationId(): string

Get the current correlation ID.

getFormValues(): array

Get the form values, e.g. ['company' => 'Acme Ltd.', 'name' => 'John Smith'].

getRequest(): \\Psr\\Http\\Message\\ServerRequestInterface

Get the current request.

Hint

Some variable resolvers are already shipped with the extension. Have a look into the folder Classes/Domain/VariableResolver for implementation details.

Example

As an example we want to resolve a variable to a cookie value.

1. Create the event listener

   <?php
   declare(strict_types=1);
   
   namespace YourVender\YourExtension\EventListener;
   
   use Brotkrueml\JobRouterBase\Event\ResolveFinisherVariableEvent;
   use Psr\Http\Message\ServerRequestInterface;
   
   final class TheCookieVariableResolver
   {
      private const COOKIE_NAME = 'the_cookie';
      private const VARIABLE = '{__theCookieValue}';
   
      public function __invoke(ResolveFinisherVariableEvent $event): void
      {
         $value = $event->getValue();
   
         if (str_pos($value, self::VARIABLE) === false) {
            // Variable is not available, do nothing
            return;
         }
   
         $cookies = $event->getRequest()->getCookieParams();
   
         $variableValue = $cookies[self::COOKIE_NAME] ?? '';
         $value = str_replace(self::VARIABLE, $variableValue, $value);
   
         $event->setValue($value);
      }
   }
   

   Important

   Variables have to start with {__. Otherwise the variable resolver is not called for a value.

2. Register your event listener in Configuration/Services.yaml

   services:
      YourVendor\YourExtension\EventListener\TheCookieVariableResolver:
         tags:
            - name: event.listener
              identifier: 'your-extension/cookie-variable-resolver'
              event: Brotkrueml\JobRouterBase\Event\ResolveFinisherVariableEvent