Ndtyjky

What is wrong with the syntax here mergeMap(names => names),?

getIds(): void { 

this.myservice

.getIds.pipe( mergeMap(id => this.getNames(id)), 

mergeMap(names => names), toArray() ) 

} 

myservce.ts has the following:

getIds():Observable<Ids>{

const url = 'http://localhost:4000';

return this.http

    .post(url, '')

    .map(({ Ids }: any) => Ids.map(item => ({Id: item.Id, 

    Name: item.Name }))) as Observable<Ids>;

}



getNames(data: Ids):Observable<any> {

  const url ='http://localhost:5000';

  return this.http

    .post(url,data)

    .pipe(map(({ Results }: any) => Results[0].results.map(item => ({Id: item.ID, Name: item.Name }))));

    }

The compiler error is (as a newbie I'm not able to figure out):

ERROR in src/app/cvetable/mcomponent.ts(132,19): error TS2345:

Argument of type '(names: {}) => {}' is not assignable to parameter 

of type '(value: {}, index: number) => ObservableInput<any>'. 

Type '{}' is not assignable to type 'ObservableInput<any>'. 

Type '{}' is not assignable to type 'Iterable<any>'. 

Property '[Symbol.iterator]' is missing in type '{}'.

There's something seriously wrong with the getIds method in your Service:

Here's how it should be. Since you're using HttpClient and your eg is in Angular 7 which uses Rxjs 6+, you'll have to chain a .pipe call to your Observable value in order to apply operators on it. Inside the .pipe call, you can then place a list of comma separated operators:

getIds(obj):Observable<Ids>{

  return this.http

    .post(this.url, obj)

    .pipe(

      map((Ids: any) => Ids.map(item => ({Id: item.Id, Name: item.Name }) ) )

    )

}

Here's an Updated StackBlitz with the errors fixed.

You should use switchMap instead of mergeMap

getIds(): void { 

   this.myservice

   .getIds.pipe(switchMap(id => this.getNames(id))) 

}