21,203 questions
2
votes
2
answers
44
views
I update a shown value from a subscription, why is my new value not shown? [duplicate]
I have an Angular component that shows a member variable of its TypeScript class. I subscribe to an rxjs Observable to update the value. I see that my rxjs Subscription is executed, but the new value ...
- 737
0
votes
1
answer
61
views
How to execute angular http calls in order
I have to make a couple of optional calls to upload files to get ids before I can send a post to a different route with those file ids.
const body = ...
const updateFile1Reference = map((file: File | ...
- 24.7k
1
vote
1
answer
42
views
Value not coming to switchMap operator
I have quite trivial Interceptor that must do the following:
Catch HttpResponse.
Find there corresponding headers.
Make request to the CORS service.
Apply JWT token to headers and proceed with ...
- 3,248
1
vote
2
answers
76
views
Manipulate Observable data prior to subscribe method call
I've been using Angular with RxJS for about a year and a half now. I feel pretty comfortable in most areas, but I'm struggling a bit with RxJS. Several times now I've found myself wanting to ...
- 5,161
1
vote
1
answer
35
views
Error object undefined in Angular project built version
I'm handing errors in my Angular app using RxJS like this:
public downloadInClient(fileName: string) {
return (source: Observable<Blob>) =>
source.pipe(
map((blob: Blob) =&...
- 77
3
votes
2
answers
41
views
Angular NGRX test a selection subscription with pipe skip
My method works the way I want it to, however, the test is failing when I add the pipe(skip(1))
How do I test an observable with a pipeable skip. Here is my method:
getSomething() {
this.store....
- 181
2
votes
2
answers
81
views
Using forkJoin for nested API calls
I am struggling to understand the best way to implement nested calls to a API, using forkJoin (without using nested observables).
I have three APIs:
API to create student (/student/)
API to add ...
- 132
0
votes
1
answer
57
views
I am updating the angular component properties inside a if block and I feel it is not updating
ngOnInit() {
this.router.events.subscribe(event => {
if (event instanceof NavigationEnd) {
if (event.url === '/common/time') {
this.zone.run(() => {
...
- 77
1
vote
1
answer
56
views
Data not being displayed on template but data is fetched
I am trying to display data using rxResource. However, data returned is always undefined. However, inspecting the network tabs shows the data is indeed being fetched and I'm just doing something wrong ...
- 411
2
votes
1
answer
55
views
How do I return two http requests sequentially in rxjs and use data from first in second call?
I've written a http function that works using switch map to get the value from one http request and use it as a parameter in the second, but how do I return not only the final http request but also ...
- 1,797
1
vote
1
answer
91
views
Retry HTTP request
I have Angular service which is used in the Angular pipe. The job of that service is to do a HTTP request and fetch translations. Idea is to have a pipe which returns a Observable that only first ...
- 325
0
votes
1
answer
81
views
How do I set an empty array as default value in toSignal?
I have a DataHandler service that calls a database service and returns the value to the calling component. The database service returns an observable of an array, while I'd like the data handler to ...
0
votes
3
answers
94
views
Filter observable without triggering HTTP request
I populate a grid with the following line of code:
this.gridData$ = this.userService.getUsers();
and this is the corresponding HTML:
[kendoGridBinding]="(gridData$ | async)!"
It works as ...
- 1,924
0
votes
0
answers
65
views
Why is this RxJS subscription never closed?
I have suspected memory leaks and stale RxJS subscriptions for a while in corporate software. I decided to investigate by writing the snippet below. It's very simple. First, it loads RxJS. Second, it ...
- 359
4
votes
1
answer
62
views
Encapsulate behaviorSubject in a service
I would like to hide the "next" interface of a BehaviorSubject while retaining its other properties, especially the possibility to get last emitted value imperatively. The idea is all state ...
1
vote
1
answer
75
views
Angular rxjs, multiple subscriptions with subject and mergeMap
I have a service that notifies that an array of categories has been filled (via a call to an API on the bootstrap of the application). As soon as these categories are ready I have to start a call to ...
- 253
1
vote
0
answers
91
views
Auto login with firebase authentication
I'm looking for a great solution for firebase authentication. I use angular with ngrx and firebase. I made authentication with these technologies but when I tried to implement auto login, it actually ...
- 11
0
votes
1
answer
40
views
How to make Jest catch an exception thrown inside an RxJS Observer?
I have a subscription to an observable, which depending on some validations on the emitted value, an exception should occur.
This exception is thrown and I can capture it in the application code, but ...
- 348
1
vote
1
answer
52
views
Initial value not displayed on mat-select component using async pipe
I'm trying to use a material select component that gets its values through an Observable with async pipe.
template:
<mat-form-field>
<mat-select
value="selectedOption$ | async&...
- 13
2
votes
1
answer
25
views
Why subject's subscriber keeps consume an error, after the first() operator, if the next emit of this subject was called in the inner tap() operator?
I've found a strange rxjs behavior that keeps bothering me, and I can't even imagine a solution to this problem.
I need to create an Observable from Subject that will either emit an error if the ...
- 65
0
votes
0
answers
39
views
Why is "this" still available in rxjs subscription [duplicate]
Looking to the code below
@Component({
.....
})
export class AngularComponent {
componentVariable: bool;
someMethod(){
this.service.subscribe(x => this.componentVariable = x)
...
0
votes
0
answers
31
views
OnInit Block with readCSV subscribe/observable function yields inconsistent results
I have an Angular OnInit block inside my "Dashboard.component" that reads a CSV file and populates a web page. If my webpage is called from my "Home.Component" web page, then the ...
- 1
1
vote
2
answers
55
views
How To Combine Responses Using RxJS merge() & from()
I have to make n (user defined) http calls. The URLs are generated programatically from user inputs. Each month must be queried separately, so n depends on the date range the user has selected. In the ...
- 98
1
vote
3
answers
265
views
How to test Angular's resource() / rxResource()?
I am trying to unittest a service which uses the new rxResource utility, introduced in Angular 19:
import { computed, inject, Injectable, signal } from '@angular/core';
import { rxResource } from '@...
- 861
0
votes
1
answer
52
views
How can I continue refreshing an observable on button click when an observable error occurs in Angular?
I'm working on an Angular application where I fetch data from an API and display it using my custom state pipe and async pipe. There is a button to refresh the API call. However, if an error occurs, ...
- 103
0
votes
0
answers
71
views
rxjs BehaviorSubject returning NULL when queried in React after browser refresh
I need to append the current user to my authHeader so the backend can authorise access to the route called. The code below exposes an rxjs BehaviorSubject to provide the user to any component that ...
- 295
0
votes
1
answer
39
views
How to convert from Observable<T[]> to Observable<T>[]?
Is there a way in RxJS to split an Observable of an array to an array of Observables, one per element?
- 21
2
votes
2
answers
49
views
Signal that an Observable with shareReplay is "stale"
I have a situation with shareReplay(1) . Note that "recalculating" result$ is expensive so I don't want to do it unless required hence I'm using shareReplay(1) in the first place.
...
1
vote
1
answer
41
views
Continue running upon result from modal dialog
The following code is for modal dialog component.
I want it to act like "confirm".
Running will proceed only after clicking 'yes' (return true) or 'no' (return false) in the dialog.
import { ...
- 657
2
votes
1
answer
122
views
Angular signalStore and HttpResource
const apiUrl = environment.apiUrl;
export const PublisherStore = signalStore(
withState(initialState),
withComputed(({fetchStatus, saveFetchStatus}) => ({
fetchPending: computed(() => ...
- 21
2
votes
3
answers
49
views
Synchronize call to 2 methods
In a component (or service) I call to Main method which calls to 2 other private methods.
export class MyService
{
private Stage1 (N : number)
{
console.log ('-->Stage1');
for (...
- 657
0
votes
1
answer
24
views
How to add two error handlers to a rxjs pipeline?
I’m given an observable that may either emit values and complete, or error. The observable can be repeated.
Consumers of this observable need to be informed if the source errors, but they also should ...
- 525
1
vote
1
answer
51
views
How to refresh and listen to the refreshed data inside one stream
The important part of my code looks somewhat like this:
data$:Observable = this.dataRefresh$.pipe(switchMap(() =>
this.http.get('url')), shareReplay());
dataRefresh$:Subject = new Subject();
...
- 33
0
votes
0
answers
41
views
How to Cancel Previous API Calls When Updating Query Params in Angular with TanStack Query
I have multiple dropdowns on a page, and each selection updates the query parameters in the URL, triggering an API call via TanStack Query.
The issue arises when I change multiple dropdowns quickly:
...
0
votes
1
answer
55
views
foo.subscribe with bar not always working
Imagine we have foo$ and bar$ and both of them are BehaviorSubjects.
I have a bug in angular that sometimes in some cases foo$.subscribe(bar$) works fine, in most casses actually.
But sometimes I have ...
1
vote
1
answer
69
views
Convert filter pipe to Angular computed signal
I use RxJS filter pipe to trigger data reload from the REST server only when selectedId is not null. How do I transfer the observable into signal/computed signal achieving same effect as with the ...
- 163
1
vote
0
answers
40
views
forkJoin([]) requests are being cancelled
I am trying to do parallel requests with forkJoin but sometimes for no reason one of the request is cancelled or one of requests returns 200 but data Failed to load response data . If I make sepratae ...
- 627
1
vote
1
answer
41
views
Angular Query Tanstack Query cleanup logic
I'm using Angular 18 with TanStack Angular Query and have a question about handling observables in the queryFn.
In my queryFn, I'm using lastValueFrom() with an HTTP request like this:
queryFn: () =&...
1
vote
1
answer
75
views
Http call is running in loop when using async in template
I have a problem and I'm looking for a solution. In a standalone component (Angular 19) with OnPush detection in the template I want to read data from observable:
@Component({
selector: 'app-profile'...
- 198
1
vote
1
answer
29
views
Angular Material Autocomplete Data Source Is Observable
I am wanting a drop-down menu that can be filtered. The autocomplete component seems ideal for this, but the example in the docs deals with the scenario where your list is a static array. My list ...
- 98
1
vote
2
answers
34
views
Angular NGXS Auth Guard: How to solve Race Condition with User State
I’m experiencing a race condition when using an auth guard with NGXS state management in an Angular application. The guard should check if the user is authenticated and has the required roles before ...
- 11
2
votes
1
answer
81
views
Sending API's progress updates periodically and saving progress
In my NestJS app, I am trying to work on something that could take anywhere between 10-20 minutes of completion. So, the user clicks on a button and an API is called which does some starts to do its ...
- 169
1
vote
1
answer
95
views
rxMethod on signal store dead after rxjs error
I'm using a ngrx signal store with rxMethod:
export const MyStore = signalStore(
{ providedIn: 'root' },
withState({ loading: false }),
withMethods((state) => {
const dataService = inject(...
- 901
1
vote
1
answer
130
views
Updated signal value is delayed in child component, if the value is passed down as an `input()`
I have a service which maintains some state using a signal.
The service also exposes an rxjs observable which emits when a certain event has taken place. This event takes place after the signal value ...
- 1,001
2
votes
1
answer
32
views
Need to load the data while form get displaying, all the data should be set in the controller, during form load
In the form which values need to be set in controller, those values should be loaded after the spinner , and during form loading ,I have tried to use async and await,
but after form get displayed ...
- 133
2
votes
2
answers
67
views
Waiting for all async requests to complete with concatMap
assuming that there are multiple ajax requests that need to execute one by one sequentially, the next one should be called when the previous is done. I can achieve that by using the concatMap RxJs ...
1
vote
1
answer
27
views
http poller using rxjs timer and waitUntil doesn't work
With rxjs 7.5.7, I return a promise when a polling http request will finally returns true after several false values, but takeUntil used is never called again.
I tried to following code:
return timer(...
- 13
0
votes
0
answers
23
views
Rxjs subject /behaviour subject emits thrice same value
I m fetching data from api and storing it in rxjs behaviour subject and dataloaded is set/emit to true. On click of button modal opens only once but when I used with tabset ngx-bootstrap modal is ...
- 193
3
votes
3
answers
73
views
Start multiple independent requests that rely on the same emitted value of another observable
I need to start 3 independent requests in a component that rely on a value emitted by another observable.
The first request provides an ID, once that ID is emitted I have to start 3 independent ...
- 253
1
vote
1
answer
88
views
Angular 19 `toObservable` causing `ng build` error TypeError: r.notifier.notify is not a function
The following code:
import { toObservable } from '@angular/core/rxjs-interop';
...
export class MyService {
readonly myData= signal<MyData| null>(null);
// toObservable creates a cold ...
- 2,739