In RxJS, the map operator takes the whole array as its parameter

implement constantA = (id: string): Observable<Array<any>>=>{

}

improve constantB = (id: string): Observable<Array<myClass>>=>{
    constantA(metroId).map((x)=>{
         return new myClass(
            x.FacilityName,
            x.ID)
    };
}

export class myClass{
    ID: string;
    Name: string;
    constructor(id: string, name: string){this.ID=id;this.Name=name;}
}

The function ConstantA produces an array of objects. This is utilized in the creation of ConstantB which generates an array of instances of myClass using the output from ConstantA.

While debugging the code, it was observed that 'x' within the map function contained the complete array from ConstantA instead of individual elements, causing properties to be inaccessible.

Is there a possible solution to convert a single Observable containing an array into an array of Observables for element processing?

Answer №1

It appears there may be a misunderstanding about how observables function.

The reason you are receiving the entire array is because that is the nature of the observable - it's an

Observable<Array<any>>
, so the map operator will return an Array<any>. If you wish to operate on individual objects, your observable should be of type Observable<any> (or even better, using a specific class like Observable<TestClass>)

You can convert an Array<T> into an Observable<T> by using the from method, which can be explored further here: http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#static-method-from

Without knowing more details about how observableA functions, it's hard to provide a specific solution tailored to your situation.

Here are some helpful resources I utilized while learning about RxJs:

Answer №2

Perhaps a second Observable is not necessary in this scenario, unless there is a specific goal you have in mind that I may be overlooking. If so, please inform me of any inaccuracies and I will make any necessary adjustments:

See live demonstration

import { Observable } from 'rxjs/Observable';
import { async } from 'rxjs/scheduler/async';
import { from } from 'rxjs/observable/from';

import { map } from 'rxjs/operators';

const metroId: string = "MyUniqueID";
const arry: Array<myClass> = [];
const observableA: (id: string) => Observable<any> = (id: string) => {
    // Customize your ID as needed
    return from([
        {
            FacilityName: 'name',
            ID: 'AnotherUniqueID'
        },
        {
            FacilityName: 'DifferentName',
            ID: 'SomeOtherID'
        }
    ], asyn);
}

observableA(metroId)
    .pipe(map(x => {
        return new myClass(
            x.FacilityName,
            x.ID)
    }))
    .subscribe(itemClass => {
        arry.push(itemClass);
    })

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