A guide to HTTP calls in Angular using httpResource()

Angular v19.2 introduced a dedicated (and experimental) function to create resources that use HTTP requests: httpResource() in the @angular/common/http package.

This function uses HttpClient under the hood, allowing us to use our usual interceptors, testing utilities, etc.

The most basic usage is to call this function with a function that returns the URL from which you want to fetch data:

readonly usersResource = httpResource<Array<UserModel>>(() => '/users');

httpResource() returns an HttpResourceRef with the same properties as ResourceRef, the type returned by resource(), as it is built on top of it (check out our blog post about Angular v19.0 to learn more about resource()):

• value is a signal that contains the deserialized JSON response body;
• status is a signal that contains the resource status (idle, loading, error, resolved, etc.);
• error is a signal that contains the error if the request fails;
• isLoading is a signal that indicates if the resource is loading;
• reload() is a method that allows you to reload the resource;
• update() and set() are methods that allow you to change the value of the resource;
• asReadonly() is a method that allows you to get a read-only version of the resource;
• hasValue() is a method that allows you to know if the resource has a value;
• destroy() is a method that allows you to stop the resource.

It also contains a few more properties specific to HTTP resources:

• statusCode is a signal that contains the status code of the response as a number;
• headers is a signal that contains the headers of the response as HttpHeaders;
• progress is a signal that contains the download progress of the response as a HttpProgressEvent.

It is also possible to define a reactive resource by using a signal in the function that defines the URL. The resource will automatically reload when the signal changes:

readonly sortOrder = signal<'asc' | 'desc'>('asc');
readonly sortedUsersResource = httpResource<Array<UserModel>>(() => `/users?sort=${this.sortOrder()}`);

If you want to skip the reload, you can return undefined from the request function (as for resource()).

If you need more fine-grained control over the request, you can also pass an HttpResourceRequest object to the httpResource() function, or a function that returns an HttpResourceRequest object in case you want to make the request reactive.

This object must have a url property and can have other options like method (GET by default), params, headers, reportProgress, etc. If you want to make the request reactive, you can use signals in the url, params or headers properties.

The above example would then look like:

readonly sortedUsersResource = httpResource<Array<UserModel>>(() => ({
  url: `/users`,
  params: { sort: this.sortOrder() },
  headers: new HttpHeaders({ 'X-Custom-Header': this.customHeader() })
}));

You can of course send a body with the request, for example for a POST/PUT request, using the body property of the request object. Note that, as we create the resource in a method, we have to pass the injector in the options as a second argument:

injector = inject(Injector);
filterUserResource: HttpResourceRef<UserModel | undefined> | undefined;

filterUser() {
  this.filterUserResource = httpResource<UserModel>(
    () => ({
      url: `/users`,
      method: 'POST',
      body: {
        name: 'JB'
      }
    }),
    {
      injector: this.injector
    }
  );

Note that we will probably keep using the HttpClient for mutations.

In these options, you can also define:

• defaultValue, a default value of the resource, to use when idle, loading, or in error;
• an equal function that defines the equality of two values;
• a map function that allows you to transform the response before setting it in the resource.

It is also possible to request something else than JSON, by using the httpResource.text(), httpResource.blob() or httpResource.arrayBuffer() functions.

Some of you may get a feeling of déjà vu with all this, as it’s quite similar to the TanStack Query library, I must insist that this is experimental and will probably evolve in the future. Let’s see what the RFC process will bring us!

Update: the RFCs are out for Resource Architecture and Resource APIS.

All our materials (ebook, online training and training) are up-to-date with these changes if you want to learn more!