Dependency Injection

1import { Injectable, Inject, container } from "canxjs";
2
3@Injectable()
4class ConfigService {
5  constructor() {
6    console.log("ConfigService initialized");
7  }
8  
9  get(key: string) {
10    return process.env[key];
11  }
12}
13
14@Injectable()
15class UserService {
16  constructor(
17    private config: ConfigService // Auto-wired
18  ) {}
19
20  getUser() {
21    const dbName = this.config.get("DB_NAME");
22    // ...
23  }
24}
25
26// Resolve instance (ConfigService is auto-injected)
27const userService = await container.resolve(UserService);

1// Define a token for the interface
2const MAIL_PROVIDER = Symbol("MAIL_PROVIDER");
3
4interface MailProvider {
5  send(to: string, body: string): void;
6}
7
8@Injectable()
9class SmtpMailer implements MailProvider {
10  send(to, body) { console.log('Sending via SMTP'); }
11}
12
13@Injectable()
14class MockMailer implements MailProvider {
15  send(to, body) { console.log('Mock email sent'); }
16}
17
18// Bind implementation to token
19container.bind(MAIL_PROVIDER, SmtpMailer);
20
21@Injectable()
22class NotificationService {
23  constructor(
24    @Inject(MAIL_PROVIDER) private mailer: MailProvider
25  ) {}
26
27  notify() {
28    this.mailer.send('user@example.com', 'Hello');
29  }
30}

1import { Injectable, Scope } from "canxjs";
2
3// Singleton (Default) - One instance per application
4@Injectable({ scope: Scope.DEFAULT })
5class SingletonService {}
6
7// Transient - New instance every time it's resolved
8@Injectable({ scope: Scope.TRANSIENT })
9class TransientService {}
10
11// Request - One instance per HTTP request
12@Injectable({ scope: Scope.REQUEST })
13class RequestContextService {
14  constructor(@Inject("request") private req: any) {}
15}