Namespaces and organizing business logic services in Symfony

I want to talk about namespacing services in Symfony, specifically Symfony3.

These are exciting times, Symfony 4 is just round the corner – coming out on November 30th – so this blog post might be irrelevant soon! Nevertheless, concepts are still the same so let´s get into it!

Lately, talking with my team in SlowCode, we defined a common way of defining services.

First rule – using a folder for logic services.

Any service which provides logic to the app would be inside a App\Service folder. This way everything is tidy, and all developers in the team know where to find them.

Second rule – using a folder for the domain name

The next layer is the domain name. This is again, to provide order. You might not think so, but when you end up with 8 domain names, and 2-3 services in each one, then things can get uggly if it’s not tidy 🙂

So for instance, let’s have a service that is related to Stock called StockAvailability, the service would end up with the namespace the folder AppBundle\Service\Stock\StockAvailability

Third rule – using . for folder separation and _ for word separation

The id of the service has to be separated by . when you enter into a new folder, and separated by _ when it’s more than one word.

So in the previous example, we would define the whole thing like so:

services:

    app.service.stock.stock_availability:
        class: AppBundle\Service\Stock\StockAvailability
        arguments:
            - '@doctrine.orm.entity_manager'
            ...

Lately in Symfony 3.3, a new way of defining services was brought up.

It´s now a good practice to define the id of the service with the full qualified name. So, instead of defining it like we did before, we would define it like so:

services:

    AppBundle\Service\Stock\StockAvailability:
    	public: true
        arguments:
            - '@doctrine.orm.entity_manager'
            ...

Declared like this, you can still get the service from the service container (with the new id of course, the full class name)

use AppBundle\Service\Stock\StockAvailability

public function fooAction(Request $request)
{
    // before Symfony 3.3, you would get it like so
    // $stockService = $this->get('app.service.stock.stock_availability');

    // in Symfony 3.3, you can get it like so
    // This is only available if you defined your service as public
    $stockService = $this->get(StockAvailability::class);
}

As Symfony’s official page point out, it’s a good practice to define your services as private, not public, and then inject any service you may need in the action inside the controller, instead of getting it from the service container (similar to the dependency injection inside services), for instance

use AppBundle\Service\Stock\StockAvailability

public function fooAction(Request $request, StockAvailability $stockService) { 
    // now we have it injected into our variable $stockService 
    // so we don't need to get it from the container 
} 

So first off, I think the id with the full class name instead of an invented nomenclature is a good thing. At least there will be no more confusion amongst different devs from the team.

About private/public services. I understand where Symfony is going, and I think restricting by ‘injecting’ instead of ‘getting’ makes code more robust, and probably more readable in the end. However, I still think there’s an upside on how things were prior to 3.3 version. Getting services from the container is VERY useful, and provices flexibility and speed.

I think that since you can still define public services, that’s what I’ll keep doing… what will you do?

More info here:
Symfony service container
Symfony 3.3 best practices
Symfony class for service id