Retrieve variable used in request from response

Question

I'm working on a function that make a certain amount of requests based on many ids. And then it picks the id of the resulting elements.

I would like to kind of propagate the id i used for the request in the response. Something like this: (illustrative only)

const fetchSomeIds = async (ids, Service) => {
    const requests = ids.map(id => { return { url: `/something/` + id + `/something-else`}});
    const responses = await Promise.all(requests.map(
        request => Service.get(request.url)
    ));
    const someIds = responses.map(element => {return {id: id/*(used in request)*/, some_id: element.data.some_id};});
    return someIds;
};

So if i use ids=[27,54] and i get some_id=133 and some_id=32. the response should look like this:

[
  { 
    "id": 27,
    "some_id": 133
  },
  {
    "id": 54,
    "some_id": 32
  }
]

Answer 1

Since Promise.all preserves the order, you can access the original array at the same index:

const someIds = responses.map((element, index) => {
   return {id: ids[index], some_id: element.data.some_id};
});

However, it might be simpler to just put the processing all in a single map callback:

function fetchSomeIds(ids, Service) {
    return Promise.all(ids.map(async id => {
        const request = {url: `/something/` + id + `/something-else`};
        const response = await Service.get(request.url);
        const element = response;
        return {id, some_id: element.data.some_id};
    }));
}