Issue TS2322: The compiler has detected a mismatch in types, where a number is being assigned to a string, which is not compatible

I'm currently working on an app where I need to retrieve posts by user before displaying a specific post based on its id when clicked. However, I encountered the following errors:

ERROR in src/app/cars/car-detail/car-detail.component.ts(25,11): error TS2322: Type 'Observable<{ _id: string; title: string; content: string; imagePath: string; creator: string; }>' is not assignable to type 'Car[]'.

The property 'includes' is missing in type 'Observable<{ _id: string; title: string; content: string; imagePath: string; creator: string; }>'.

src/app/cars/car-detail/car-detail.component.ts(26,11): error TS2322: Type 'number' is not assignable to type 'string'.

import { Input, Component, OnInit } from '@angular/core';
import { Car } from '../car.model';
import { CarsService } from '../cars.service';
import { ActivatedRoute, Params } from '@angular/router';


@Component({
  selector: 'app-post-detail',
  templateUrl: './post-detail.component.html',
  styleUrls: ['./post-detail.component.css']
})
export class PostDetailComponent implements OnInit {
  @Input() post: Post[] = [];
  @Input() id: string;
  constructor(
    private postsService: PostsService,
    private route: ActivatedRoute
  ) { }

  ngOnInit() {
    this.route.params
      .subscribe(
        (params: Params) => {
          this.post = this.postsService.getPost(this.id);
          this.id = +params['id'];
        }
      );
  }

}

How can I resolve these issues?

Answer №1

1)

@Input() id: string is declared as a string, but when you attempt to convert it to a number using the + operator in this.id = +params['id'];, an error occurs. To fix this, change the type of @Input() id: string to number.

2)

this.post = this.postsService.getPost(this.id);

Since getPost method returns an observable, you must subscribe to it and then assign the result to the post property.

this.postsService.getPost(this.id).subcribe(res => this.post = res);

Answer №2

A similar scenario arose for me while experimenting with this specific tutorial.

An error message TS2322 popped up: 'Type 'number' is not assignable to type 'string'

Here are the errors I encountered while implementing a node REST API.

Error TS2322: Type 'string' is not assignable to type 'number | FindOperator<number>'.

27     const product = await repository.find({ id: req.params.id });

To resolve this, all I had to do was change the variable type from id:number to id: string.

The variable used in this function is declared in another file. The declaration type of that particular variable (named as 'id' in my case) was not compatible with the variable type causing the error.

Hence, visit the declaration location and ensure the variable type is either number or string based on compatibility with the rest of the functions.

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