Materialize/Dematerialize Map Operators

Represents all the notifications from the inner source and projected outer Observable (from map-something/transform operator) as next emissions marked with their original types within MapNotification objects.

Works like materialize but for map-something (transform) operators.

Operators

• Maps:
  • matMergeMap()
  • matConcatMap()
  • matSwitchMap()
  • matExhaustMap()
• Scans:
  • matMergeScan()

Dematerialize

dematerializeMap()

Parts

Part operators used for extract information from MapNotifications.

• ValuePart
• ErrorPart
• ProgressPart
• UpdatedAtPart

Classes have .add() and .select() operator methods: ValuePart.add(), ValuePart.select().

Combine

combineParts() - operator for combine MapNotification and parts to Map object. Allows to store the last state of all events in one Map object.

Map Notification

MapNotification contains outer value with index and inner Notification with index.

Installation

npm i materialize-map

Example

import { matMergeMap, ProgressPart, UpdatedAtPart, combineParts, ValuePart, ErrorPart } from "materialize-map";
import { merge, of, throwError } from "rxjs";
import { delay, share } from "rxjs/operators";

const helloUser$ = merge(of("Ray"), of("Ellie").pipe(delay(50)), of("Error").pipe(delay(100))).pipe(
    matMergeMap((name, idx) => {
        if (idx === 2) return throwError(`And hello to you, ${name}!`);
        return of(`Hello, ${name}!`).pipe(delay(100));
    }),
    combineParts(ValuePart.add(), ErrorPart.add(), ProgressPart.add(), UpdatedAtPart.add()),
    share()
);

const value$ = helloUser$.pipe(ValuePart.select());
const error$ = helloUser$.pipe(ErrorPart.select());
const progressCount$ = helloUser$.pipe(ProgressPart.select());
const updatedAt$ = helloUser$.pipe(UpdatedAtPart.select());

const log = (title: string, value: string | number | boolean) => console.log(title.padStart(20, ".") + ": " + value);

value$.subscribe((value) => log("Value", value));
error$.subscribe((error) => log("Error", String(error)));
progressCount$.subscribe((count) => log("Progress Count", count));
updatedAt$.subscribe((date) => log("Updated At", date.toISOString()));

// ......Progress Count: 0
// ......Progress Count: 1
// ......Progress Count: 2
// ...............Value: Hello, Ray!
// ......Progress Count: 1
// ..........Updated At: 2021-06-26T00:20:11.614Z
// ......Progress Count: 2
// ...............Error: And hello to you, Error!
// ......Progress Count: 1
// ..........Updated At: 2021-06-26T00:20:11.618Z
// ...............Value: Hello, Ellie!
// ......Progress Count: 0
// ..........Updated At: 2021-06-26T00:20:11.677Z