fetchNextPage method

Implementation

Future<void> fetchNextPage() async {
  if (isFetchingNextPage.value || !hasNextPage.value || isDisposed) {
    return;
  }

  isFetchingNextPage.value = true;
  update(); // Update UI to show loading footer

  try {
    // 1. Fetch the new page using the stored param
    final newPage = await infiniteFetcher(_nextPageParam);

    if (isDisposed) return;

    // 2. Append to existing pages
    final currentPages = data.value ?? [];
    final allPages = [...currentPages, newPage];

    // 3. Update the reactive data
    // We use setData to ensure timestamps are updated in the cache
    data.value = allPages;

    // Manually update cache entry since we modified data outside standard fetch()
    ZenQueryCache.instance.updateCache(queryKey, allPages, DateTime.now());

    // 4. Calculate the cursor for the NEXT fetch
    final nextParam = getNextPageParam(newPage, allPages);
    _nextPageParam = nextParam;
    hasNextPage.value = nextParam != null;

    // 5. Ensure status is success
    if (status.value != ZenQueryStatus.success) {
      status.value = ZenQueryStatus.success;
    }

    // Clear any previous errors since this succeeded
    error.value = null;
  } catch (e) {
    if (!isDisposed) {
      // We generally set the error state but keep the old data
      error.value = e;
      // Note: We do NOT set status to ZenQueryStatus.error because
      // we still have valid pages displayed.
      // The UI should check 'error' to show a toast/snackbar.
    }
  } finally {
    if (!isDisposed) {
      isFetchingNextPage.value = false;
      update();
    }
  }
}