Symfony4: inject service into controller __construct (constructor) - php

Question

I am having trouble accessing an injected service in the constructor of one of my controllers.
Per http://symfony.com/doc/current/service_container/injection_types.html I believe I have done the injection correctly, however when I try to load a view from the controller, I get the following error:
Argument 1 passed to Regions\AnalyticsBundle\Controller\PatternsController::__construct()
must be an instance of Regions\AnalyticsBundle\Controller\PatternCacheService, instance of
Regions\AnalyticsBundle\Service\PatternCacheService given, called
in /var/tmp/symfony/cache/dev/ContainerLoHUcSH/getPatternsControllerService.php on line 9
It seems like the error indicates that the type hinting in the constructor is trying making it look for an instance in the *\Controller\* namespace instead of the *\Services\* namespace - what am I doing wrong or not seeing here?
Details of my setup are as follows...
Symfony 4.1.0, PHP 7.2.5
services.yaml
services:
...
pattern_cache_service:
class: Regions\AnalyticsBundle\Service\PatternCacheService
public: true
Regions\AnalyticsBundle\Controller\PatternsController:
arguments: ['#pattern_cache_service']
Controller:
namespace Regions\AnalyticsBundle\Controller;
class PatternsController extends BaseController
{
private $pcs;
public function __construct(PatternCacheService $pcs)
{
$this->pcs = $pcs;
}
}

Answer 1

You forgot a use in your Controller, making PHP think that your service is in the same namespace as your controller.
<?php
namespace Regions\AnalyticsBundle\Controller;
use Regions\AnalyticsBundle\Service\PatternCacheService;
class PatternsController extends BaseController
{
private $pcs;
public function __construct(PatternCacheService $pcs)
{
$this->pcs = $pcs;
}
}
This was actually raised as part of your error message
Argument 1 passed to Regions\AnalyticsBundle\Controller\PatternsController::__construct()
must be an instance of Regions\AnalyticsBundle\Controller\PatternCacheService
When what you expected was your controller to need an instance of Regions\AnalyticsBundle\Service\PatternCacheService

Answer 2

The class PatternCacheService cannot be found in the namespace Regions\AnalyticsBundle\Controller.
Add an import:
<?php
namespace Regions\AnalyticsBundle\Controller;
use Regions\AnalyticsBundle\Service\PatternCacheService;
class PatternsController extends BaseController
{
private $pcs;
public function __construct(PatternCacheService $pcs)
{
$this->pcs = $pcs;
}
}
For reference, see
http://php.net/manual/en/language.namespaces.importing.php

Answer 3

You don't need a service definition for pattern_cache_service. It should autowire your service if autowire: true is set.
PatternCacheService should be private as you don't want to access it from within container. Suggested practise!
You don't need a service definition for PatternsController either.
Note: You should not use "bundles" anymore in Symfony 4 so I would get rid of AnalyticsBundle.
Note: Better organise your configuration files as show here: Organising route, service and parameter configuration files in symfony 4 applications.
This should suffice:
services.yaml
services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: '../src/*'
exclude: '../src/{Entity,....so on .....,Kernel.php}'
App\Controller\:
resource: '../../src/Regions/AnalyticsBundle/Controller'
tags: ['controller.service_arguments']
PatternsController
namespace Regions\AnalyticsBundle\Controller;
use Regions\AnalyticsBundle\Service\PatternCacheService;
class PatternsController
{
private $pcs;
public function __construct(PatternCacheService $pcs)
{
$this->pcs = $pcs;
}
}