Injecting an arbitrary parameter to a service - symfony

Question

I'm wondering if there is a sort of best practice for the following case.
For instance, I have several services and inject them all as an array into a "factory" service. Then I call a method of this factory and want to get only one service depends on some conditions. After that I execute this service and get a result...
However, some of these services require a random string that I get from a client's request.
Of cause, I can call a service's method with this string as a parameter but several services do not require this string and I'll get "unused variable" in the method.
I guess that I could get service from the factory and then call a setter to add this string into the service. But it does not look like a stateless service.
Is there a more elegant solution to pass parameters that I could not inject into service nor use the setter for it?
Here how it looks in my code
First, I have an interface of all servers that I want to check. The service should support a customer an then it should render information from a DTO.
interface Renderable {
public function supports(Customer $customer);
public function render(CustomerDTO $dto);
}
Next, I have several services. This one uses DTO to render data.
class ServiceOne implements Renderable
{
public function suppots(Customer $customer)
{
return $customer->getPriority() === 1;
}
public function render(CustomerDTO $dto)
{
return 'One: '.$dto->getName();
}
}
However, some services do not need any DTO to render, they just provide a hardcoded value.
class ServiceTwo implements Renderable
{
public function suppots(Customer $customer)
{
return $customer->getPriority() !== 1;
}
// service does not use DTO, it simply output result
// so, I'll get a notice about unused variable
// and I can not remove it from the method since it is in interface
public function render(CustomerDTO $dto)
{
return 'Two';
}
}
This is a factory. It has all services injected as an array. Then it checks and returns the first service that supports a customer instance.
class ServiceFactory
{
/** #var Renderable[] */
private $services;
public function __construct(iterable $services)
{
$this->services = $services;
}
public function getRenderer(Customer $customer)
{
foreach ($this->services as $service)
{
if ($service->supports($customer)
{
return $service;
}
}
}
}
Here like I use factory and its result
$customer = ...; // it comes from a database
$request = ...; // it comes from a http request
$renderService = $factory->getRenderer($customer);
$customerDTO = CustomerDTO::createFromData([
'customerUid' => $customer->getUid(),
'date' => new \DateTime(),
'name' => $request->getSheetUid(),
'tags' => $request->getTags(),
]);
$renderService->render($customerDTO);
So, I have to call Renderer::render with a DTO instance. But some services do not use it to "render" data. I also can not inject it into a renderer service since this object (DTO) is built in a runtime when all services already injected. I also can not inject a RequestStack into service.

Answer 1

Since your parameter came from request - it can't be directly injected into service. Depending on actual logic of your services you can consider one of approaches listed below. Let's call your "random string that came from a client's request" a $requestParam for further reference.
In both cases you will need to get your $requestParam from actual Request object and pass it somewhere else. It can be done in a different ways, I would propose to create listener (e.g. RequestParamListener) for kernel.request event and put here a piece of code that takes parameter from Request and pass it further into this listener. Into approaches listed below I will assume that $requestParam will be passed in this way.
1. Separate provider
You can create separate class (e.g. RequestParamProvider) that will act as provider of this $requestParam for other services. It will receive $requestParam from RequestParamListener and other services that needs to get $requestParam will need to inject this provider and use its getRequestParam() method to obtain required parameter.
From my point of view it is the simplest approach and I would recommend it.
2. Direct injection by factory
Since you have some factory service - you can pass this $requestParam directly into factory and let it to initialize other services. Less flexible because you will need to implement initialization logic by itself and maintain it while project evolves.
3. Direct injection using interface
You can create separate interface (e.g. RequestParamAwareInterface) that will contain setRequestParam() method and let all classes that needs this $requestParam to implement this interface. After that you will need to write separate compiler pass that will collect all such classes (by iterating over ContainerBuilder and looking for implementation of particular interface by class inside service's definition) and pass array of these services to your RequestParamListener. Listener in its turn will be obligated to pass $requestParam for each of given services.
This approach will let your application to grow without need to sync $requestParam injection logic. However it will came at a cost of preliminary instantiation of all affected services regardless of actual further use of created instances.