How are we supposed to use useInfiniteQuery with REST APis that use self/next/prev urls

[anilanar]

For example, see Confluence pagination: https://developer.atlassian.com/server/confluence/pagination-in-the-rest-api/

So pageParams are urls to other pages. Therefore there is no "initialPageParam". But with v5, initialPageParam is required.

We can work around it by either passing empty string as initialPageParam (and in queryFn, check if pageParam is empty string or not) or by passing the original url as initialPageParam. But that's far from being elegant. Why make it required?

[TkDodo]

initialPageParam is required because a) we can infer the type for pageParam from it and b) we used to just pass undefined for the first page, but that causes trouble in serialization because undefined is not serializable.

You can also set your initialPageParam to the url itself and then always use it:

useInfiniteQuery({
  queryKey: ['thing'],
  queryFn: ({ pageParam }) => fetch(pageParam),
  initialPageParam: '/thing',
  getNextPageParam: (lastPage) => lastPage._links.next,
})

[syz51]

hey qq. So in the case of initialData being set, the initialPageParam is never used, right? Because the initial request will never be sent. In this case, the initialPageParam is only used to infer the type for pageParam.
For example:

useInfiniteQuery({
    queryKey: ["videos"],
    queryFn: async ({ pageParam }) => {
      return await fetchVideos(pageParam);
    },
    getNextPageParam: (lastPage: Video[], _) =>
      lastPage.length === 0
        ? undefined
        : {
            lastStreamingDate: lastPage[lastPage.length - 1].streamingDate,
            lastCode: lastPage[lastPage.length - 1].code,
          },
    initialPageParam: {
      lastStreamingDate: "",
      lastCode: "",
    },
    initialData: { pages: [initialVideos], pageParams: [] },
  });

[TkDodo]

well if you refetch the query and this is the first page / only page in the cache, we will use the initialPageParam to refetch that page.