possible to perform a combined req_perform_sequential together with req_perform_iterative?

[deschen1]

httr2 offers options for paginated requests (req_perform_iterative) as well as requests that need to be structured as a list (request_sequential). For the latter one, a common use case example would be an API that provides data from countries and a single API call accepts only one country in the request body.

I can build up such a request "loop" and fetch the data as follows:

countries <- c("DE", "US", "FR")

req_countries <- map(.x = countries,
                     .f = ~request("https://apis.test.com") |>
                       req_headers("Accept" = "application/json",
                                   'auth1' = "abc",
                                   'apikey' = "xyz"))

resp_countries <- req_perform_sequential(req = req_countries)

However, imagine the API uses pagination for each country, i.e. each response has several pages. I can use the above request and map it with req_perform_iterative:

is_complete <- function(resp)
{
  resp_body_json(resp)$pagination$hasNext == FALSE
}

resp_countries <- req_countries |> 
  map(.f = ~req_perform_iterative(req = .x,
                                  next_req = iterate_with_offset(param_name = "pageNumber",
                                                                 start = 0,
                                                                 offset = 1,
                                                                 resp_complete = is_complete),
                                  max_reqs = Inf,
                                  on_error = "return"))

So I need to map twice, once for building the request and then again when fetching the data.

I'm wondering if there is a way or if it would be a valuable new feature for httr2 to offer a combined function, e.g. by adding the req_perform_iterative functionality directly in req_perform_sequential?

So that the call could look like:

resp_countries <- req_countries |> 
  req_perform_sequential(req = req_countries,
                         iterative = TRUE,
                         next_req = iterate_with_offset(param_name = "pageNumber",
                                                        start = 0,
                                                        offset = 1,
                                                        resp_complete = is_complete),
                         max_reqs = Inf,
                         on_error = "return")

[hadley]

This would be a special case of #456