Argument of type '{}' is not assignable to parameter of type in Angular 8

Question

I have a method for handling errors:

private handleError<T>(operation = 'operation', result?: T) {
    return (error: any): Observable<T> => {
      console.error(error);
      this.log(`${operation} failed: ${error.message}`);

      return of(result as T);
    };
  }

  private log(message: string) {
    console.log(message);
  }

and I want to use it inside my method:

getMyStructure(): Observable<HttpResponse<StructureResponse>> {
    return this.http.get< StructureResponse >(
        localUrl).pipe(retry(3), catchError(this.handleError<StructureResponse>('getMyStructure', {})));
}

but the last {} throws me an error. The StructureResponse is an Interface with some fields. In my understanding I should put there some (empty?) object of StructureResponse but I'm no longer sure. Can you help me with that?

this is the StructureResponse:

interface SomeStructure {
  content: MyStructure[];
  page: number;
  size: number;
  totalElements: number;
  totalPages: number;
  last: boolean
}

Binara Thambugala · Accepted Answer · 2020-01-11 23:08:12Z

3

Add ? to each property.

interface SomeStructure {
  content?: MyStructure[];
  page?: number;
  size?: number;
  totalElements?: number;
  totalPages?: number;
  last?: boolean
}

Use Observable<StructureResponse> instead Observable<HttpResponse<StructureResponse>> as below.

getMyStructure(): Observable<StructureResponse> {
    return this.http.get< StructureResponse >(
        localUrl).pipe(retry(3), catchError(this.handleError<StructureResponse>('getMyStructure', {})));
}

edited Jan 11, 2020 at 23:08

answered Jan 11, 2020 at 21:27

Binara Thambugala

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Comments

Elias Dal Ben · Accepted Answer · 2020-01-11 20:43:55Z

0

If you pass an empty object, the only way that it would assign to a interface, would be that the attributes from the interface are all optional (with ?), otherwise you need to at least show your attributes in your object with null or another value.

answered Jan 11, 2020 at 20:43

Elias Dal Ben

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2 Comments

randomuser1 Over a year ago

can you please check my interface? I added it to the question - knowing that, could you please help me with resolving my problem?

randomuser1 Over a year ago

I added the ? but I'm getting the following error now during compilation:

TS2322: Type 'Observable< SomeStructure >' is not assignable to type 'Observable<HttpResponse< SomeStructure >>'.   Type 'SomeStructure' is missing the following properties from type 'HttpResponse< SomeStructure >': body, type, clone, headers, and 4 more.

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