Angular HttpClient and other data fetching clients

Because TanStack Query's fetching mechanisms are agnostically built on Promises, you can use literally any asynchronous data fetching client, including the browser native fetch API, graphql-request, and more.

HttpClient is a powerful and integrated part of Angular, which gives the following benefits:

• Mock responses in unit tests using provideHttpClientTesting.
• Interceptors can be used for a wide range of functionality including adding authentication headers, performing logging, etc. While some data fetching libraries have their own interceptor system, HttpClient interceptors are integrated with Angular's dependency injection system.
• HttpClient automatically informs PendingTasks, which enables Angular to be aware of pending requests. Unit tests and SSR can use the resulting application stableness information to wait for pending requests to finish. This makes unit testing much easier for Zoneless applications.
• When using SSR, HttpClient will cache requests performed on the server. This will prevent unneeded requests on the client. HttpClient SSR caching works out of the box. TanStack Query has its own hydration functionality which may be more powerful but requires some setup. Which one fits your needs best depends on your use case.

As TanStack Query is a promise based library, observables from HttpClient need to be converted to promises. This can be done with the lastValueFrom or firstValueFrom functions from rxjs.

@Component({
  // ...
})
class ExampleComponent {
  private readonly http = inject(HttpClient)

  readonly query = injectQuery(() => ({
    queryKey: ['repoData'],
    queryFn: () =>
      lastValueFrom(
        this.http.get('https://api.github.com/repos/tanstack/query'),
      ),
  }))
}

@Component({
  // ...
})
class ExampleComponent {
  private readonly http = inject(HttpClient)

  readonly query = injectQuery(() => ({
    queryKey: ['repoData'],
    queryFn: () =>
      lastValueFrom(
        this.http.get('https://api.github.com/repos/tanstack/query'),
      ),
  }))
}

Since Angular is moving towards RxJS as an optional dependency, it's expected that HttpClient will also support promises in the future.

Support for observables in TanStack Query for Angular is planned.