Generic type Subject<T> requires 1 type argument(s). - Angular

Question

I'm getting data from my service and I've red about it's important to unsubscribe after subscribe, and here is how I did it:

export class RItemComponent implements OnInit {

    apiPath = environment.apiUrl;
    private ngUnsubscribe: Subject = new Subject();

    constructor(private _sharedService: SharedService) { }

    rItems: Product[];

    ngOnInit() {
    this._sharedService.
        getReceiptItem().takeUntil(this.ngUnsubscribe).
        subscribe(products => this.rItems = products);
    }

    ngOnDestroy() {
    this.ngUnsubscribe.next();
    this.ngUnsubscribe.complete();
    }
}

But now I'm getting an error:

Generic type Subject<T> requires 1 type argument(s). subscribe

I don't understand why?

Any kind of help would be awesome, thanks!

Solution 1

The Subject class has a generic type parameter in TypeScript. This means, that instances of this class can only be created by passing an additional type parameter, like this:

private ngUnsubscribe: Subject<MyClass> = new Subject();

Solution 2

Add a generic type for subject

private ngUnsubscribe: Subject<any> = new Subject();

Comments

[ggradnig]

You're welcome :-) There are books written about ReactiveX, but good starting point is the following: reactivex.io/documentation/subject.html. Concerning generic type parameters, have a look at the TypeScript doc: typescriptlang.org/docs/handbook/generics.html

[GreeneCreations]

any is discouraged. There's almost always a more accurate type. If you really don't know or can't know what the type will be, then consider using the new type unknown. typescriptlang.org/docs/handbook/release-notes/…