Combine a list with an observable list

Question

Combine a list with an observable list

Consider having 3 different types of lists - two basic lists and one observable list.

The challenge arises when you need to combine a non-observable list with the observable one.
The current approach may seem unconventional for observables.

listToMerge = []
listObs$: BehaviorSubject<[]> = new BehaviorSubject([]);
listObsCopy = []

Elements have already been added to the listObs using the next method

listObs$.next(someStuff);
listObsCopy = somestuff;

Below is an attempt to merge them together.

listToMerge = listObsCopy.concat(someOtherStuff);
listObs$.next(listToMerge as any);

typescript rxjs

Answer 1

Answer №1

Are you in search of a solution that merges all arrays into one using RxJS? Check out the code snippet below!

    import { BehaviorSubject, merge } from 'rxjs';
    import { concatAll, take, tap, toArray } from 'rxjs/operators';

    // Subject (and Observable with take(1) to ensure completion.)
    let listSubject: BehaviorSubject<string[]> = new BehaviorSubject<string[]>(['B1', 'B2']);
    let listObs$ = listSubject.asObservable().pipe(take(1));

    // List to Merge 
    let listToMerge = ['1', '2'];

    let mergedObs$ = merge(listToMerge, listObs$).pipe(concatAll(), toArray());

    mergedObs$.subscribe((value) => console.log('merged array:', value));

https://stackblitz.com/edit/typescript-ukxwep?file=index.ts

The key lies in utilizing the concatAll() operator to flatten the arrays and then employing the toArray() operator to consolidate them into a single array.

It's worth noting that I've included take(1) in the observable for the subject. The subscription will only commence once the Observable is completed.

Answer 2

Are you in search of a solution that merges all arrays into one using RxJS? Check out the code snippet below!

    import { BehaviorSubject, merge } from 'rxjs';
    import { concatAll, take, tap, toArray } from 'rxjs/operators';

    // Subject (and Observable with take(1) to ensure completion.)
    let listSubject: BehaviorSubject<string[]> = new BehaviorSubject<string[]>(['B1', 'B2']);
    let listObs$ = listSubject.asObservable().pipe(take(1));

    // List to Merge 
    let listToMerge = ['1', '2'];

    let mergedObs$ = merge(listToMerge, listObs$).pipe(concatAll(), toArray());

    mergedObs$.subscribe((value) => console.log('merged array:', value));

https://stackblitz.com/edit/typescript-ukxwep?file=index.ts

The key lies in utilizing the concatAll() operator to flatten the arrays and then employing the toArray() operator to consolidate them into a single array.

It's worth noting that I've included take(1) in the observable for the subject. The subscription will only commence once the Observable is completed.

Answer 3

Answer №2

If you have an array, turning it into an observable and combining it with another array is simple using the from() method:

Check out this resource for more information on how to use from()

const firstArray = from([1, 2, 3, 4, 5]);
const secondArray = from([6, 7, 8]);
firstArray.concat(secondArray).subscribe()

Answer 4

If you have an array, turning it into an observable and combining it with another array is simple using the from() method:

Check out this resource for more information on how to use from()

const firstArray = from([1, 2, 3, 4, 5]);
const secondArray = from([6, 7, 8]);
firstArray.concat(secondArray).subscribe()

Combine a list with an observable list

Answer №1

Answer №2

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