A simple Dependency Injection (DI) library for TypeScript supporting Singleton and Transient service lifetimes.
First, install the package via npm or yarn:
npm install di-injectable
yarn add di-injectable
- Define Services: Create your service classes and use the @Injectable decorator and use
ServiceLifetime
enum to register your services as Singleton or Transient.. - Resolve Services: Use the ServiceProvider to resolve instances of your services.
Let's walk through a complete example.
- Define Services Create some simple services and use the @Injectable decorator.
// src/services/logger.ts
import { Injectable } from 'di-injectable';
@Injectable(ServiceLifetime.Singleton)
export class Logger {
log(message: string) {
console.log(`Logger: ${message}`);
}
}
// src/services/userService.ts
import { Injectable, Inject } from 'di-injectable';
import { Logger } from './logger';
@Injectable()
export class UserService {
constructor(@Inject(Logger) private logger: Logger) {}
getUser() {
this.logger.log('Getting user...');
return { id: 1, name: 'John Doe' };
}
}
- Resolve Services Use the ServiceProvider to resolve instances of your services.
// src/app.ts
import { ServiceProvider } from 'di-injectable';
import { UserService } from './services/userService';
const serviceProvider = new ServiceProvider();
const userService = serviceProvider.resolve<UserService>(UserService);
const user = userService.getUser();
console.log(user);
- Defining Services:
- The
Logger
service is a simple logger class. - The
UserService
class depends on theLogger
service. The@Inject
decorator is used to inject theLogger
service - into the UserService constructor.
- The
- Registering Services:
- We register the
Logger
service as a Singleton, meaning only one instance ofLogger
will be created and shared. - We register the
UserService
as a Transient by default, meaning a new instance ofUserService
will be created every time it is resolved.
- We register the
- Resolving Services:
- We create a
ServiceProvider
instance. - We resolve an instance of
UserService
using theserviceProvider
. TheUserService
will have theLogger
instance injected into it due to the@Inject
decorator.
- We create a
- Singleton: Only one instance of the service is created and shared.
- Transient: A new instance of the service is created every time it is requested.
- ServiceProvider:
resolve<T>(token: any): T
: Resolves an instance of the service.Injectable
: Decorator to mark a class as injectable as register it.Inject
: Decorator to inject dependencies into the constructor.
Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
Please make sure to update tests as appropriate.
- Create Your Services: Define your services using the
@Injectable
decorator and useServiceLifetime
enum to register your services as Singleton or Transient. - Resolve Services: Use
ServiceProvider
to resolve instances of your services.