2.6. Dependency Injection
2.6.1. Amaç
Daha iyi test edilebilir, bakım yapılabilir ve genişletilebilir kod elde etmek için gevşek bağlı bir mimari uygulamak.
2.6.2. Kullanım
DatabaseConfiguration
gets injected and DatabaseConnection
will get all that it
needs from $config
. Without DI, the configuration would be created
directly in DatabaseConnection
, which is not very good for testing and
extending it.
2.6.3. Örnekler
Doctrine2 ORM bağımlılık aktarımını kullanır. Örneğin bir
Connection
nesnesi, yapılandırma (configuration) nesnesine bağımlanmıştır. Test amacıyla bir yapılandırma yapaylaması (configuration mock) kolayca oluşturulabilir veConnection
nesnesine aktarılabilir.many frameworks already have containers for DI that create objects via a configuration array and inject them where needed (i.e. in Controllers)
2.6.4. UML Diyagramı

2.6.5. Kod
Bu kodu Github üzerinde de bulabilirsiniz.
DatabaseConfiguration.php
1<?php
2
3declare(strict_types=1);
4
5namespace DesignPatterns\Structural\DependencyInjection;
6
7class DatabaseConfiguration
8{
9 public function __construct(
10 private string $host,
11 private int $port,
12 private string $username,
13 private string $password
14 ) {
15 }
16
17 public function getHost(): string
18 {
19 return $this->host;
20 }
21
22 public function getPort(): int
23 {
24 return $this->port;
25 }
26
27 public function getUsername(): string
28 {
29 return $this->username;
30 }
31
32 public function getPassword(): string
33 {
34 return $this->password;
35 }
36}
DatabaseConnection.php
1<?php
2
3declare(strict_types=1);
4
5namespace DesignPatterns\Structural\DependencyInjection;
6
7class DatabaseConnection
8{
9 public function __construct(private DatabaseConfiguration $configuration)
10 {
11 }
12
13 public function getDsn(): string
14 {
15 // this is just for the sake of demonstration, not a real DSN
16 // notice that only the injected config is used here, so there is
17 // a real separation of concerns here
18
19 return sprintf(
20 '%s:%s@%s:%d',
21 $this->configuration->getUsername(),
22 $this->configuration->getPassword(),
23 $this->configuration->getHost(),
24 $this->configuration->getPort()
25 );
26 }
27}
2.6.6. Test
Tests/DependencyInjectionTest.php
1<?php
2
3declare(strict_types=1);
4
5namespace DesignPatterns\Structural\DependencyInjection\Tests;
6
7use DesignPatterns\Structural\DependencyInjection\DatabaseConfiguration;
8use DesignPatterns\Structural\DependencyInjection\DatabaseConnection;
9use PHPUnit\Framework\TestCase;
10
11class DependencyInjectionTest extends TestCase
12{
13 public function testDependencyInjection()
14 {
15 $config = new DatabaseConfiguration('localhost', 3306, 'user', '1234');
16 $connection = new DatabaseConnection($config);
17
18 $this->assertSame('user:1234@localhost:3306', $connection->getDsn());
19 }
20}