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DEPENDENCY INJECTION Entenda pra nunca mais esquecer!

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Sou Junior Grossi twitter.com/junior_grossi github.com/jgrossi

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PACIÊNCIA!

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https://github.com/corcel/corcel

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https://www.glofox.com/careers

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AGENDA Dependency Injection Dependency Inversion (SOLID) Dependency Injection Container

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DEPENDENCY INJECTION?

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Thorben Janssen "Dependency injection is a programming technique that makes a class independent of its dependencies. It achieves that by decoupling the usage of an object from its creation. This helps you to follow SOLID’s dependency inversion and single responsibility principles." https://stackify.com/dependency-injection/

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class AvatarRequestUploader { private AwsS3Client $s3Client; // PHP 7.4 public function __construct() { $this­>s3Client = new AwsS3Client( // credentials + configs ); } public function upload(Request $request): string { $avatar = $this­>findAvatarInRequest($request); $avatarUrl = $this­>s3Client­>store($avatar); return $avatarUrl; } } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

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public function __construct() { $this­>s3Client = new AwsS3Client( // credentials + configs ); } class AvatarRequestUploader 1 { 2 private AwsS3Client $s3Client; // PHP 7.4 3 4 5 6 7 8 9 10 11 public function upload(Request $request): string 12 { 13 $avatar = $this­>findAvatarInRequest($request); 14 $avatarUrl = $this­>s3Client­>store($avatar); 15 16 return $avatarUrl; 17 } 18 } 19

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public function __construct(AwsS3Client $s3Client) { $this­>s3Client = $s3Client; } class AvatarRequestUploader 1 { 2 private AwsS3Client $s3Client; 3 4 5 6 7 8 9 public function upload(Request $request): string 10 { 11 $avatar = $this­>findAvatarInRequest($request); 12 $avatarUrl = $this­>s3Client­>store($avatar); 13 14 return $avatarUrl; 15 } 16 } 17

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OBSERVAÇÕES Agora, para instanciar AvatarRequestUploader precisamos injetar AwsS3Client A classe AvatarRequestUploader agora depende da AwsS3Client

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DEPENDENCY INJECTION NOVA CLASSE UPLOADER? $s3Client = new AwsS3Client([ /* parameters */]); $avatarRequestUploader = new AvatarRequestUploader($s3Client); $avatarRequestUploader­>upload($request); $avatarMiddlewareUploader = new AvatarMiddlewareUploader($s3Client); $avatarMiddlewareUploader­>upload($request);

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Dependency Injection é basicamente mover todas as dependências para o __construct

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FORMAS DE INJETAR DEPENDÊNCIAS Constructor Injection Setter Injection Method Injection

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CONSTRUCTOR INJECTION ✅ Forma mais aconselhada de DI. class A { private Foo $foo; private Bar $bar; public function __construct(Foo $foo, Bar $bar) { $this­>foo = $foo; $this­>bar = $bar; } }

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SETTER INJECTION ⚠ Muita permissão / vulnerabilidade! class Authorizer { private Logger $logger; public function setLogger(Logger $logger) { $this­>logger = $logger; } }

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METHOD INJECTION Processamento de dados de input / request. class UserController { public function create(SaveUserRequest $request) { $data = $request­>validated(); // Code... } }

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DEPENDENCY INVERSION? (SOLID) "Dependency Inversion Principle (DIP)"

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Robert C. Martin (Uncle Bob) Design Principles and Design Patterns "Depend upon Abstractions. Do not depend upon concretions." https://bit.ly/2W6XAVm/

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public function __construct(AwsS3Client $s3Client) { $this­>s3Client = $s3Client; } class AvatarRequestUploader 1 { 2 private AwsS3Client $s3Client; 3 4 5 6 7 8 9 public function upload(Request $request): string 10 { 11 $avatar = $this­>findAvatarInRequest($request); 12 $avatarUrl = $this­>s3Client­>store($avatar); 13 14 return $avatarUrl; 15 } 16 } 17

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Agora também precisamos fazer upload dos avatars para o Dropbox.

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AwsS3Client é uma classe concreta DropboxClient é uma classe concreta Solução? CloudStorageInterface (abstração) Abstração = Interface

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interface CloudStorageInterface { public function store(string $content): string; }

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class MyAwsS3Client implements CloudStorageInterface { private AwsS3Client $client; public function __contruct(AwsS3Client $client) { $this­>client = $client; } public function store(string $content): string { return $this­>client­>store($content); } }

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class MyDropboxClient implements CloudStorageInterface { private DropboxClient $client; public function __contruct(DropboxClient $client) { $this­>client = $client; } public function store(string $content): string { $name = $this­>generateRandomName(); $result = $this­>client­>send($name, $content); if (!$result) { throw new CloudStorageUploadException(); } return $this­>getUrlFor($name); } }

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public function __construct(CloudStorageInterface $cloudStorage) { $this­>cloudStorage = $cloudStorage; } $avatarUrl = $this­>cloudStorage­>store($avatar); class AvatarRequestUploader 1 { 2 private CloudStorageInterface $cloudStorage; 3 4 5 6 7 8 9 public function upload(Request $request): string 10 { 11 $avatar = $this­>findAvatarInRequest($request); 12 13 14 return $avatarUrl; 15 } 16 } 17

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(new AvatarRequestUploader($myS3Client)) ­>upload($request); (new AvatarRequestUploader($mydropboxClient)) ­>upload($request); $s3Client = new AwsS3Client([ /* parameters */]); 1 $myS3Client = new MyAwsS3Client($s3Client); 2 3 4 5 6 $dropboxClient = new DropboxClient([ /* parameters */]); 7 $mydropboxClient = new MyDropboxClient($dropboxClient); 8 9 10 11

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DEPENDENCY INJECTION CONTAINER "Livro de Receita" Fonte: https://bit.ly/2ExbFDS

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PROCESSO Você "ensina" ao container como criar seus objetos, informando suas dependências. Você solicita uma instância de um objeto ao Container. O Container sabe como instanciar, e então te retorna a instância desejada.

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Basta pedir ao Container: $s3Client = new AwsS3Client([ /* parameters */]); $myS3Client = new MyAwsS3Client($s3Client); (new AvatarRequestUploader($myS3Client)) ­>upload($request); $container = Container::instance(); $avatarUploader = $container­>get(AvatarRequestUploader::class); $avatarUploader­>upload($request);

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Ou utilizar como dependência de outra classe: class ChangeAvatarAction { private AvatarRequestUploader $avatarUploader; public function __construct(AvatarRequestUploader $avatarUploader) { $this­>avatarUploader = $avatarUploader; } public function __invoke(ServerRequestInterface $request): ResponseInterface { $avatarUrl = $this­>avatarUploader­>upload($request); return new JsonResponse([ 'avatar' => $avatarUrl, ], 201); } }

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PSR-11: CONTAINER INTERFACE - PHP-FIG Psr\Container\ContainerInterface Métodos: get() e has() Psr\Container\ContainerExceptionInterface Psr\Container\NotFoundExceptionInterface

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league/container A SIMPLE BUT POWERFUL PSR-11 DEPENDENCY INJECTION CONTAINER http://container.thephpleague.com

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namespace Acme; class Foo { public Bar $bar; public function __construct(Bar $bar) { $this­>bar = $bar; } } class Bar {}

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$container = new League\Container\Container; $container­>add(Acme\Foo::class)­>addArgument(Acme\Bar::class); $container­>add(Acme\Bar::class); $foo = $container­>get(Acme\Foo::class); var_dump($foo instanceof Acme\Foo); // true var_dump($foo­>bar instanceof Acme\Bar); // true

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Service Provider não é exclusivo do Laravel $container = new League\Container\Container; $container­>addServiceProvider( Acme\ServiceProvider\SomeServiceProvider::class ); $foo = $container­>get(Acme\Foo::class);

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class SomeServiceProvider extends AbstractServiceProvider { protected array $provides = [ Acme\Foo::class, Acme\Bar::class, ]; public function register(): void { $container = $this­>getContainer(); $container­>add(Acme\Foo::class)­>addArgument(Acme\Bar::class); $container­>add(Acme\Bar::class); } }

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Auto wiring também não é exclusivo do Laravel Funciona apenas para objetos! $container = new League\Container\Container; $container­>delegate( new League\Container\ReflectionContainer ); $foo = $container­>get(Acme\Foo::class);

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Atenção: evite usar o Container como dependência ⚠ É muita liberdade! Pode ferir SRP! class Foo { private Bar $foo; private Baz $baz; public function __construct(ContainerInterface $container) { $this­>bar = $container­>get(Bar::class); $this­>baz = $container­>get(Baz::class); } }

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OUTROS PACOTES illuminate/container pimple/pimple php­di/php­di https://github.com/illuminate/container https://github.com/silexphp/Pimple https://github.com/PHP-DI/PHP-DI

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CONSIDERAÇÕES SOBRE DI Permite flexibilização da arquitetura Código plugável (troca de componentes mais fácil) Centralização de objetos (pra quê?)

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BÔNUS Testes usando DI

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Unit Test public function test_avatar_can_be_uploaded_through_the_request(): void { // $s3Client = new AwsS3Client([ /* parameters */]); // $myS3Client = new MyAwsS3Client($s3Client); $cloudStorageMock = \Mockery::mock(CloudStorageInterface::class); $cloudStorageMock­>shoudReceive('store')­>andReturn('http://avatar.com'); $uploader = new AvatarRequestUploader($cloudStorageMock); $avatarUrl = $uploader­>upload(new Request(['avatar' => 'foo'])); $this­>assertEquals('http://avatar.com', $avatarUrl); }

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Integration/Feature Test public function test_user_can_change_avatar(): void { $cloudStorageMock = \Mockery::mock(CloudStorageInterface::class); $cloudStorageMock­>shoudReceive('store')­>andReturn('http://avatar.com'); $container = Container::instance(); $container­>replace(CloudStorageInterface::class, $cloudStorageMock); $response = $this­>json('PATCH', '/1.0/users/change­avatar', [ 'avatar' => 'foo', ]); $result = $response­>getContent()­>toArray(); $this­>assertEquals('http://avatar.com', $result['avatar']); }

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Testando Events / Listeners > Feature Test: POST /1.0/users private array $events = [ Events\UserWasCreated::class => [ Listeners\SendWelcomeEmail::class, Listeners\RegisterUserAtIntercom::class, Listeners\UploadAvatarIfPresent::class, Listeners\SendWelcomeSlackNotification::class, ], ];

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USE DI E DI CONTAINER Vale a pena! Seu projeto agradece!

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OBRIGADO Perguntas? Dúvidas? Críticas? Sugestões? twitter.com/junior_grossi github.com/jgrossi grossi.dev