Installation
npm i --save nestjs-custom-injector
Links
https://nestjs-custom-injector.site15.ru/api/#/symbol-token/SymbolTokenController_whatSaysAnimals - Demo application with nestjs-custom-injector.
https://github.com/EndyKaufman/nestjs-custom-injector/tree/develop/apps/demo/src/app/symbol-token - Example.
Usage
Create common interface with token in animal-provider.interface.ts
export const ANIMAL_PROVIDER = Symbol('ANIMAL_PROVIDER');
export interface AnimalProviderInteface {
type: string;
say(): string;
}
Create first type of logic for cats in animal-cats.service.ts
import { Injectable } from '@nestjs/common';
import { AnimalProviderInteface } from './animal-provider.interface';
@Injectable()
export class AnimalCatsService implements AnimalProviderInteface {
type = 'cat';
say(): string {
return 'meow';
}
}
Create second type of logic for dogs in animal-dogs.service.ts
import { Injectable } from '@nestjs/common';
import { AnimalProviderInteface } from './animal-provider.interface';
@Injectable()
export class AnimalDogsService implements AnimalProviderInteface {
type = 'dog';
say(): string {
return 'woof';
}
}
Create controller animals.controller.ts
import { Controller, Get, Query } from '@nestjs/common';
import { CustomInject } from 'nestjs-custom-injector';
import {
AnimalProviderInteface,
ANIMAL_PROVIDER,
} from './animal-provider.interface';
@Controller('animals')
export class AnimalsController {
@CustomInject(ANIMAL_PROVIDER, { multi: true })
private animalProviders!: AnimalProviderInteface[];
@Get('animal-types')
animalTypes() {
return this.animalProviders.map((animalProvider) => animalProvider.type);
}
@Get('what-says-animals')
whatSaysAnimals() {
return this.animalProviders.map(
(animal) => `${animal.type} say ${animal.say()}`
);
}
@Get('who-say')
whoSay(@Query('voice') voice: string) {
const animal = this.animalProviders.find(
(animal) => animal.say() === voice
);
if (!animal) {
return { error: `I don't know who say ${voice}` };
}
return `${animal.type} say ${animal.say()}`;
}
}
Append all logic to main app module app.module.ts
import { Module } from '@nestjs/common';
import { CustomInjectorModule } from 'nestjs-custom-injector';
import { AnimalCatsService } from './animal-cats.service';
import { AnimalDogsService } from './animal-dogs.service';
import { AnimalsController } from './animals.controller';
@Module({
...
imports: [
...
CustomInjectorModule.forRoot(),
CustomInjectorModule.forFeature({
providers: [{ provide: ANIMAL_PROVIDER, useClass: AnimalCatsService }],
}),
CustomInjectorModule.forFeature({
providers: [
{ provide: ANIMAL_PROVIDER, useValue: new AnimalDogsService() },
],
}),
...
],
controllers: [
...
AnimalsController
...
]
...
})
export class AppModule {}
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