@toss/nestjs-aop

@toss/nestjs-aop ·

A way to gracefully apply AOP to nestjs
Use nestjs managed instances in any decorators gracefully

Table of Contents

1. Installation
2. Usage
3. References
4. Contributing
5. License

Installation

npm install @toss/nestjs-aop
pnpm add @toss/nestjs-aop
yarn add @toss/nestjs-aop

Usage

1. Import AopModule

@Module({
  imports: [
    // ...
    AopModule,
  ],
})
export class AppModule {}

2. Create symbol for LazyDecorator

export const CACHE_DECORATOR = Symbol('CACHE_DECORATOR');

3. Implement LazyDecorator using nestjs provider

metadata is the second parameter of createDecorator.

@Aspect(CACHE_DECORATOR)
export class CacheDecorator implements LazyDecorator<any, CacheOptions> {
  constructor(private readonly cache: Cache) {}

  wrap({ method, metadata: options }: WrapParams<any, CacheOptions>) {
    return (...args: any) => {
      let cachedValue = this.cache.get(...args);
      if (!cachedValue) { 
        cachedValue = method(...args);
        this.cache.set(cachedValue, ...args);
      }
      return cachedValue;
    };
  }
}

4. Add LazyDecoratorImpl to providers of module

@Module({
  providers: [CacheDecorator],
})
export class CacheModule {}

5. Create decorator that marks metadata of LazyDecorator

options can be obtained from the warp method and used.

export const Cache = (options: CacheOptions) => createDecorator(CACHE_DECORATOR, options)

6. Use it!

export class SomeService {
  @Cache({
    // ...options(metadata value)
  })
  some() {
    // ...
  }
}

References

• https://toss.tech/article/nestjs-custom-decorator
• https://youtu.be/VH1GTGIMHQw?t=2973

Contributing

We welcome contribution from everyone in this project. Read CONTRIBUTING.md for detailed contribution guide.

License

MIT © Viva Republica, Inc. See LICENSE for details.