Error when trying to inject a service into an angular component “EXCEPTION: Can't resolve all parameters for component”, why?

Question

I\'ve built a basic app in Angular, but I have encountered a strange issue where I cannot inject a service into one of my components. It injects fine into any of the three o

Answer 1

Gotcha!

If none of the above answers helped you, maybe you are importing some element from the same file where a component is injecting the service.

I explain better:

This is the service file:

// your-service-file.ts
import { helloWorld } from 'your-component-file.ts'

@Injectable()
export class CustomService() {
  helloWorld()
}

This is the component file:

@Component({..})
export class CustomComponent {
  constructor(service: CustomService) { }
}

export function helloWorld() {
  console.log('hello world');
}

So it causes problems even if the symbol isn't inside the same component, but just inside the same file. Move the symbol (it can be a function, a constant, a class and so on...) elsewhere and the error will fade away