Function transferCacheInterceptorFn

packages/common/http/src/transfer_cache.ts:278–342

(
  req: HttpRequest<unknown>,
  next: HttpHandlerFn,
)

}

export function transferCacheInterceptorFn(
  req: HttpRequest<unknown>,
  next: HttpHandlerFn,
): Observable<HttpEvent<unknown>> {
  const options = inject(CACHE_OPTIONS);
  if (!canUseOrCacheRequest(req, options)) {
    return next(req);
  }

  const transferState = inject(TransferState);
  const originMap = inject(HTTP_TRANSFER_CACHE_ORIGIN_MAP, {optional: true});
  const requestUrl =
    typeof ngServerMode !== 'undefined' && ngServerMode && originMap
      ? mapRequestOriginUrl(req.url, originMap)
      : req.url;
  const storeKey = makeCacheKey(req, requestUrl);

  const cachedResponse = retrieveStateFromCache(
    req,
    options,
    transferState,
    /** originMap */ null,
    storeKey,
    /** skipUseCacheChecks */ true,
  );

  if (cachedResponse) {
    return of(cachedResponse);
  }

  const event$ = next(req);
  if (typeof ngServerMode !== 'undefined' && ngServerMode) {
    // Request not found in cache. Make the request and cache it if on the server.
    return event$.pipe(
      tap((event: HttpEvent<unknown>) => {
        if (event instanceof HttpResponse) {
          const {headers, body, status, statusText} = event;

          // Only cache successful HTTP responses that are not non-cacheable.
          if (
            !options.includeNonCacheableRequests &&
            (hasUncacheableCacheControl(headers) || hasSetCookieHeader(headers))
          ) {
            return;
          }

          const {transferCache: requestOptions, responseType} = req;
          const headersToInclude = getHeadersToInclude(options, requestOptions);

          transferState.set<TransferHttpResponse>(storeKey, {
            [BODY]:
              responseType === 'arraybuffer' || responseType === 'blob' ? toBase64(body) : body,
            [HEADERS]: getFilteredHeaders(headers, headersToInclude),
            [STATUS]: status,
            [STATUS_TEXT]: statusText,
            [REQ_URL]: requestUrl,
            [RESPONSE_TYPE]: responseType,
          });