nj-request-scope

Performant request scope dependency injection for NestJS framework using express server

Description

nj-request-scope library solves NestJs request-scope dependency injection problems:
* bubbling up the injection chain - NestJS documentation
* request-scope performance issues - NestJS documentation

This solution is based on the build-in javascript Proxy design pattern. For every request, only the proxy's target object is changed to the new request-scope instance instead of creating all injection chain objects.

Installation

``console
npm install nj-request-scope
`

There are also a few peer dependencies that have to be satisfied:
`json
"@nestjs/common": ">8.0.0",
"@nestjs/core": ">8.0.0",
"@nestjs/platform-express": ">8.0.0",
"express-http-context": ">1.2.4",
"reflect-metadata": ">0.1.12",
"rxjs": "^7.1.0"
`
Especially express-http-context which is not required by NestJS by default.

nj-request-scope was tested with NestJs 8.x & 9.x & 10.x & 11.x versions.

Usage

To use nj-request-scope in NestJS module you have to add import of `RequestScopeModule` in the module class decorator:
`typescript
import { RequestScopeModule } from 'nj-request-scope';

@Module({
imports: [RequestScopeModule],
})
`

Next, there are two ways of using nj-request-scope.

1. Inject express request object into class constructor with `NJRS_REQUEST` token:
`typescript
import { NJRS_REQUEST } from 'nj-request-scope';
[...]
constructor(@Inject(NJRS_REQUEST) private readonly request: Request) {}
`

2. Change class inject scope to request-scope with `@RequestScope()` decorator:
`typescript
import { RequestScope } from 'nj-request-scope';

@Injectable()
@RequestScope()
export class RequestScopeService {
`

Limitations

Proxy handler implements only most common methods:
* `get`
* `has`
* `set`
* `getPrototypeOf`
* `getOwnPropertyDescriptor`
* `ownKeys``

If you need other methods implemented please feel free to contribute.
ProxyHandler implementation

Example project

https://github.com/kugacz/nj-request-scope-example

License

nj-request-scope is MIT licensed.