Function makeHttpResourceFn

packages/common/http/src/resource.ts:237–283

(responseType: ResponseType)

  | ((ctx: ResourceParamsContext) => HttpResourceRequest | undefined);

function makeHttpResourceFn<TRaw>(responseType: ResponseType) {
  return function httpResource<TResult = TRaw>(
    request: RawRequestType,
    options?: HttpResourceOptions<TResult, TRaw>,
  ): HttpResourceRef<TResult> {
    if (ngDevMode && !options?.injector) {
      assertInInjectionContext(httpResource);
    }
    const injector = options?.injector ?? inject(Injector);

    const cacheOptions = injector.get(CACHE_OPTIONS, null, {optional: true});
    const transferState = injector.get(TransferState, null, {optional: true});
    const originMap = injector.get(HTTP_TRANSFER_CACHE_ORIGIN_MAP, null, {optional: true});

    const getInitialStream = (req: HttpRequest<unknown> | undefined) => {
      if (cacheOptions && transferState && req) {
        const cachedResponse = retrieveStateFromCache(req, cacheOptions, transferState, originMap);
        if (cachedResponse) {
          try {
            const body = cachedResponse.body as TRaw;
            const parsed = options?.parse ? options.parse(body) : (body as unknown as TResult);
            return signal({value: parsed});
          } catch (e) {
            if (typeof ngDevMode === 'undefined' || ngDevMode) {
              console.warn(
                `Angular detected an error while parsing the cached response for the httpResource at \`${req.url}\`. ` +
                  `The resource will fall back to its default value and try again asynchronously.`,
                e,
              );
            }
          }
        }
      }
      return undefined;
    };

    return new HttpResourceImpl(
      injector,
      (ctx: ResourceParamsContext) => normalizeRequest(ctx, request, responseType),
      options?.defaultValue,
      options?.debugName,
      options?.parse as (value: unknown) => TResult,
      options?.equal as ValueEqualityFn<unknown>,
      getInitialStream,
    ) as HttpResourceRef<TResult>;
  };
}

function normalizeRequest(
  ctx: ResourceParamsContext,