Facing issues with Laravel's IoC and Singleton.
I have the following singleton class:
class ConcreteClass
{
function __construct() {Log::info('I iz created...');}
}
And the following service provider:
class ConcreteClassServiceProvider extends ServiceProvider
{
public function register()
{
$this->app->singleton('ConcreteClass', function () {
return new ConcreteClass();
});
}
}
However with every App::make('ConcreteClass'), public function __construct(ConcreteClass $concrete) in a single request will cause the log to have a I iz created... which makes it highly doubtful the singleton thing works in Laravel. I am most probably wrong with the configuration. Please help me with it. Thank you.
I'm not sure how you use your instance but it could be a namespace thing. When I tried instantiating my singleton by specifying the full path, for example:
#inject('foo', 'App\.....\FooSingleton');
It did not work.
I had to do it by only specifying the name without the path, i.e:
#inject('foo', 'FooSingleton');
Why? I don't know. It's still a mystery to me.
Related
I'm working with Laravel 5.8 and it's an Online Store project written by other programmers.
Basically I have faced something weird that never seen before.
Let's say we have this at a Controller method:
$payment = CourseRegistrationFacade::insertCourseRegisterInformation($courseId,$date,$memberId,$userId);
And then we goto the CourseRegistrationFacade and it goes like this:
class CourseRegistrationFacade extends BaseFacade
{
}
So the whole class is empty but it extends another Facade which is BaseFacade and it goes like this:
class BaseFacade extends Facade
{
protected static function getFacadeAccessor()
{
return static::class;
}
protected static function shouldProxyTo($class)
{
app()->bind(self::getFacadeAccessor(), $class)
}
}
And that's it !
I don't really know where the heal is insertCourseRegisterInformation !!
So if you know how this Facade works, please let me know...
Here is the full code of BaseFacade.php:
namespace App\Facades;
use Illuminate\Support\Facades\Facade;
class BaseFacade extends Facade
{
protected static function getFacadeAccessor()
{
return static::class;
}
public static function shouldProxyTo($class)
{
app()->bind(self::getFacadeAccessor(), $class);
}
}
Search in the code for:
CourseRegistrationFacade::shouldProxyTo(
Most likely in the service provider that line is somewhere registering that facade to some concrete implementation of a class. Then check the contents of the class (the argument passed to shouldProxyTo).
Inside that class there should be a method called insertCourseRegisterInformation.
The way facades work is they resolve the class out of the container and then call the method you call statically.
So for example, let's say you have a UserService.php with a method register() and that class is mapped to a UserServiceFacade.php. When you do UserServiceFacade::register(), __callStatic will get the facade accessor (actual class) from the container, then call the register() method of that class.
You can understand better by inspecting __callStatic inside Facade.php.
Essentially UserServiceFacade::register() is the same as doing:
$userService = app()->make(UserService::class);
$userService->register()
By using the facade you can hide the concrete implementation and could possibly switch it to something else in the future by just changing it in a single place.
I think there must be a Provider exists for that Facade which is initializing its associated class and insertCourseRegisterInformation method definition must be declared in it. Please find that provider and then you'll find its associated class from that Provider code. I think you can find all registered providers from config/app.php
These reference articles might help you.
Reference 1:
https://grafxflow.co.uk/blog/mvc/adding-global-custom-class-facades-laravel-5
Reference 2: http://www.expertphp.in/article/how-to-create-custom-facade-in-laravel-52
I am currently facing a very interesting dilemma with my architecture and implementation.
I have an interface called ServiceInterface which have a method called execute()
Then I have two different implementations for this interface: Service1 and Service2, which implements the execute method properly.
I have a controller called MainController and this controller has a "type-hint" for the ServiceInterface (dependency injection), it means that both, Service1 and Service2, can be called as resolution for that dependency injection.
Now the fun part:
I do not know which of those implementations to use (Service1 or Service2) because I just know if I can use one or other based on a user input from a previous step.
It means the user choose a service and based on that value I know if a can use Service1 or Service2.
I am currently solving the dependency injection using a session value, so depending of the value I return an instance or other, BUT I really think that it is not a good way to do it.
Please, let me know if you faced something similar and, how do you solve it, or what can I do to achieve this in the right way.
Thanks in advance. Please let me know if further information is required.
Finally, after some days of researching and thinking a lot about the best approach for this, using Laravel, I finally solved it.
I have to say that this was especially difficult in Laravel 5.2 because, in this version, the Session middleware only is executed in the controllers used in a route, it means that if for some reason I used a controller (not linked for a rote) and try to get access to the session it is not going to be possible.
So, because I cannot use the session, I decided to use URL parameters. Here you have the solution approach; I hope some of you found it useful.
so, you have an interface:
interface Service
{
public function execute();
}
Then a couple of implementations for the interface:
Service one:
class ServiceOne implements Service
{
public function execute()
{
.......
}
}
Service two.
class ServiceTwo implements Service
{
public function execute()
{
.......
}
}
The interesting part is that I have a controller with a function with a dependency with the Service interface. Still, I need to resolve it dynamically to ServiceOne or ServiceTwo based on user input. So:
The controller
class MyController extends Controller
{
public function index(Service $service, ServiceRequest $request)
{
$service->execute();
.......
}
}
Please note that ServiceRequest, validated that the request already have the parameter that we need to resolve the dependency (call it 'service_name')
Now, in the AppServiceProvider we can resolve the dependency in this way:
class AppServiceProvider extends ServiceProvider
{
public function boot()
{
}
public function register()
{
//This specific dependency is going to be resolved only if
//the request has the service_name field stablished
if(Request::has('service_name'))
{
//Obtaining the name of the service to be used (class name)
$className = $this->resolveClassName(Request::get('service_name')));
$this->app->bind('Including\The\Namespace\For\Service', $className);
}
}
protected function resolveClassName($className)
{
$resolver = new Resolver($className);
$className = $resolver->resolveDependencyName();
return $className;
}
}
So now all the responsibility is for the Resolver class. This class basically use the parameter passed to the constructor to return the full name (with namespace) of the class that is going to be used as an implementation of the Service interface:
class Resolver
{
protected $name;
public function __construct($className)
{
$this->name = $className;
}
public function resolveDependencyName()
{
//This is just an example, you can use whatever as 'service_one'
if($this->name === 'service_one')
{
return Full\Namespace\For\Class\Implementation\ServiceOne::class;
}
if($this->name === 'service_two')
{
return Full\Namespace\For\Class\Implementation\ServiceTwo::class;
}
//If none, so throw an exception because the dependency can not be resolved
throw new ResolverException;
}
}
Well, I really hope it helps some of you.
Best wishes!
---------- EDIT -----------
I just realize that it is not a good idea to use the request data directly inside the container of Laravel. It really is going to cause some trouble in the long term.
The best way is to directly register all the possible instances supported (serviceone and servicetwo) and then resolve one of them directly from a controller or a middleware, so then is the controller "who decides" what service to use (from all the available) based on the input from the request.
In the end, it works at the same, but it is going to allow you to work more naturally.
I have to say thanks to rizqi, a user from the questions channel of the slack chat of Laravel.
He personally created a golden article about this. Please read it because it solves this issue completely and in a very right way.
laravel registry pattern
The fact that you define that your controller works with ServiceInterface is ok
If you have to choose the concrete implementation of the service basing on a previous step (that, as i've understood, happens in a previous request) storing the value in session or in database is right too, as you have no alternative: to choose the implementation you have to know the value of the input
The important point is to 'isolate' the resolution of the concrete implementation from the input value in one place: for example create a method that takes this value as a parameter and returns the concrete implementation of the service from the value:
public function getServiceImplementation($input_val)
{
switch($input_val)
{
case 1 : return new Service1();
case 2 : return new Service2();
}
}
and in your controller:
public function controllerMethod()
{
//create and assign the service implementation
$this->service = ( new ServiceChooser() )->getServiceImplementation( Session::get('input_val') );
}
In this example i've used a different class to store the method, but you can place the method in the controller or use a Simple Factory pattern, depending on where the service should be resolved in your application
It's an interesting problem. I'm currently using Laravel 5.5 and have been mulling it over. I also want my service provider to return a specific class (implementing an interface) based upon user input. I think it's better to manually pass the input from the controller so it's easier to see what's going on. I would also store the possible values of the class names in the config.
So based upon the Service classes and interface you've defined above i came up with this:
/config/services.php
return [
'classes': [
'service1' => 'Service1',
'service2' => 'Service2',
]
]
/app/Http/Controllers/MainController.php
public function index(ServiceRequest $request)
{
$service = app()->makeWith(ServiceInterface::class, ['service'=>$request->get('service)]);
// ... do something with your service
}
/app/Http/Requests/ServiceRequest.php
public function rules(): array
$availableServices = array_keys(config('services.classes'));
return [
'service' => [
'required',
Rule::in($availableServices)
]
];
}
/app/Providers/CustomServiceProvider.php
class CustomServiceProvider extends ServiceProvider
{
public function boot() {}
public function register()
{
// Parameters are passed from the controller action
$this->app->bind(
ServiceInterface::class,
function($app, $parameters) {
$serviceConfigKey = $parameters['service'];
$className = '\\App\\Services\\' . config('services.classes.' . $serviceConfigKey);
return new $className;
}
);
}
}
This way we can validate the input to ensure we are passing a valid service, then the controller handles passing the input from the Request object into the ServiceProvider. I just think when it comes to maintaining this code it will be clear what is going on as opposed to using the request object directly in the ServiceProvider.
PS Remember to register the CustomServiceProvider!
I find the best way to deal with this is using a factory pattern. You can create a class say ServiceFactory and it has a single method create() it can accept an argument which is used to dynamically choose which concrete class to instantiate.
It has a case statement based on the argument.
It will use App::make(ServiceOne::class) or App::make(ServiceTwo::class).depending on which one is required.
You are then able to inject this into your controller (or service which depends on the factory).
You can then mock it in a service unit test.
Recently, I had to implement a similar logic where I was to implement a method to perform mobile top-ups for multiple networks in our application. So, I decided to implement the logic using Factory and Bridge pattern. Factory to create an instance of the concrete Service class based on the user input, and then, the Bridge pattern to set closely related classes into separate hierarchies and route the request to the respective class.
In the controller's method, both Factory and Service classes are injected. The TopUpServiceFactory's create method creates an object of the concrete class. The TopUpService class then routes the request to that concrete class method.
class TopUpController extends Controller
{
public function topUp(Request $request, TopUpServiceFactoryInterface $serviceFactory, TopUpServiceInterface $topUpService)
{
$serviceFactory->create($request->networkCode);
$topUpService->TopUp($request->all());
}
}
The TopUpServiceFactoryInterface and TopUpServiceInterface are bound to TopUpServiceFactory and TopUpService concrete Classes respectively in Service Container.
class AppServiceProvider extends ServiceProvider
{
public function register()
{
$this->app->bind(TopUpServiceFactoryInterface::class, TopUpServiceFactory::class);
$this->app->bind(TopUpServiceInterface::class, TopUpService::class);
}
}
The create method accepts user input and creates an object of the respective class based on the user input.
class TopUpServiceFactory implements TopUpServiceFactoryInterface
{
public function create(string $networkCode)
{
switch ($networkCode) {
case 'network1':
app()->bind(NetworkServiceInterface::class, Network1Service::class);
break;
case 'network2':
app()->bind(NetworkServiceInterface::class, Network2Service::class);
break;
default:
app()->bind(NetworkServiceInterface::class, DefaultNetworkService::class);
break;
}
}
}
The Service Class then picks the object of NetworkService Class and forwards the request.
class TopUpService implements TopUpServiceInterface
{
public function topUp(array $requestParams)
{
$networkService = app()->get(NetworkServiceInterface::class);
$networkService->topUp($requestParams);
}
}
All network's concrete classes implement a common interface NetworkServiceInterface, which is used to inject dependency dynamically, implementing Liskov Substitution Principle
class Network1Service implements NetworkServiceInterface
{
public function topUp(array $requestParam)
{
Process Topup ......
}
}
class Network2Service implements NetworkServiceInterface
{
public function topUp(array $requestParam)
{
Process Topup ......
}
}
...
I wanna ask about design pattern.
Why should I use dependency injection in constructor, not import it ('use statement')?
For example:
in my controller:
class AuthController extends Controller {
public function __construct(UserGateway $userGateway)
{
$this->userGateway = $userGateway;
}
public function doSomething()
{
$this->userGateway->foo();
}
}
Why don't use just like this instead?
use Acme\UserGateway;
class AuthController extends Controller {
public function doSomething()
{
UserGateway::foo();
}
}
Many thanks.
Assuming UserGateway is not laravel facade: here's the biggest advantage of injecting stuff this way: in the future, you might redefine what UserGateway actually is, and supply some other class (most often, it's subclass) instead of it like this:
$this->app->bind(UserGateway::class, function ($app) {
return new NewUserGateway();
});
This is extremely useful for overriding some parts of your code, especially if you're using same packages across multiple projects. And it does not require you to change the AuthController's code.
If UserGateway is a Facade, the only benefit you'll get is a better code navigation with you IDE, since it will know what class exactly are you referencing (assuming that you didn't re-bound it).
I have a class that I am trying to swap out the facade usage of Crypt::encrypt with dependency injection:
<?php namespace App\Libraries;
use Illuminate\Encryption\Encrypter;
class MyClass
{
public function __construct(Encrypter $encrypter)
{
$this->encrypter= $encrypter;
}
public function myMethod()
{
$this->encrypter->crypt('somevalue');
}
}
The wrong instance is getting instantiated:
Argument 1 passed to App\Libraries\MyClass::__construct() must be an
instance of Illuminate\Encryption\Encrypter, instance of
Illuminate\Encryption\McryptEncrypter given
The facade resolves without an issue but I'd like to understand why DI is failing.
use Illuminate\Support\Facades\Crypt;
Crypt::encrypt('somevalue');
Any help appreciated.
It because you had registered McryptEncrypter instead of Encrypter.
It could be if you have unsupported cipher or key.
For more information look in Illuminate\Encryption\EncryptionServiceProvider.
use Illuminate\Contracts\Encryption\Encrypter;
class MyClass
{
public function __construct(Encrypter $encrypter)
{
$this->encrypter= $encrypter;
}
public function myMethod()
{
$this->encrypter->crypt('somevalue');
}
}
Also, follow SOLID principles Depend upon Abstractions. Do not depend upon concretions. Replace Encrypter concrete realisation to it interface.
The facade resolves without an issue but I'd like to understand why DI is failing.
Facade works because he just resolves what you register, in your case it McryptEncrypter
Hope it will help.
The FQCN of the Laravel Encrypter interface (highlight by me) is:
Illuminate\Contracts\Encryption\Encrypter
The method you defined:
public function __construct(Encrypter $encrypter)
{
$this->encrypter= $encrypter;
}
does not make use of that interface. Unless you don't make use of the correct interface, PHP will rightfully and totally correct present you the error message and luckily prevents your program from running:
Argument 1 passed to App\Libraries\MyClass::__construct() must be an instance of Illuminate\Encryption\Encrypter, instance of Illuminate\Encryption\McryptEncrypter given
You have breached the contract!
Use the correct interface for the argument so that DI works as intended.
I have a custom class App/Http/Responder, which had a few methods to build a specific JSON response back in my application. I want to test my controller in isolation, so I'm trying to inject my dependencies via the constructor.
My plan was to simply create a service provider, attach bind it to the $app and then, as per the docs, let it be automatically resolved:
public function register()
{
$this->app->bind('responder', function()
{
return new App\Http\Responder($this->app['cache'], $this->app['app'], new JsonResponse, $this->app['config']);
});
}
I then add this to my config/app.php.
Okay, so now my Responder and it's dependancies are bound to the app, as responder.
Now I thought I'd be able to inject Responder into my controller constructor, and Laravel would be able to automatically resolve this from the IoC container:
class AreasController extends BaseController {
protected $responder;
public function __construct(Responder $responder)
{
$this->responder = $responder;
}
However I get Class Responser does not exist.
The only way I can get it working, without using the App::make() Facade, is to inject the app into my controller:
use Illuminate\Foundation\Application as App;
class AreasController extends BaseController {
protected $app;
public function __construct(App $app)
{
$this->app = $app;
}
I can then do $this->app['responder']->method().
Obviously I'm missing something, but I want to keep away from using Facades in my app so I can test.
If you want to type hint classes to be resolved in the IOC container, you should bind the actual class name with namespace:
$this->app->bind('App\Http\Responder', function()
{
return new App\Http\Responder($this->app['cache'], $this->app['app'], new JsonResponse, $this->app['config']);
});
Technically the container would still resolve this class, because it's a concrete class that can be found, but the way you're doing allows to inject other IOC-bound resources, which is a good practice.
Then, when you wish to have this class injected for you, type hint the full path to the class as you normally would:
use App\Http\Responder;
class AreasController extends BaseController {
protected $responder;
public function __construct(Responder $responder)
{
$this->responder = $responder;
}
}
Also, for what it's worth, your error indicates that you misspelled "Responder" as "Responser".