Encountering an Issue:
browser_adapter.js:76 Error: Cannot resolve all parameters for NestedComponent(undefined). Make sure they all have valid type or annotations.
at NoAnnotationError.BaseException [as constructor]
Diving Deeper Into the Problem:
A service is defined as follows:
@Injectable()
export class MyService {
doSomething() {
console.log("This service is performing operations");
}
}
The service can be injected into components without any issues, like this example:
@Component({
selector: 'parent-component',
template: '<p>This works perfectly!</p>',
providers: [MyService]
})
export class ParentComponent {
constructor(private _myService: MyService) {}
ngOnInit() {
this._myService.doSomething();
}
}
Problems arise when attempting to inject the service into nested components, illustrated by the following code snippet:
@Component({
selector: 'nested-component',
template: "<p>This doesn't work as expected. :(</p>",
providers: [MyService]
})
export class NestedComponent {
constructor(private _myService: MyService) {}
ngOnInit() {
this._myService.doSomething();
}
}
Upon trying to integrate the nested component into the parent component, the aforementioned error occurs. How can I address this issue?
@Component({
selector: 'parent-component',
template: '<nested-component></nested-component>',
directives: [NestedComponent]
})
export class ParentComponent {
}
It is worth noting that even after including MyService in the bootstrap function of the application, the error persists:
function main() {
return bootstrap(App, [
// Dependencies of our App
HTTP_PROVIDERS,
ROUTER_PROVIDERS,
MyService,
ELEMENT_PROBE_PROVIDERS // remove in production
])
.catch(err => console.error(err));
}
document.addEventListener('DOMContentLoaded', main);