Cannot return documents based off a sorted index using Fauna DB

I'm bumbling my way through adding a back-end to my site and have decided to get acquainted with graphQL. I may be structuring things totally the wrong way, however from following some tutorials I have a React front-end (hosted on Vercel), so I have created an api folder in my app to make use of Vercel's serverless functions. I'm using Apollo server and I decided to go with Fauna as my database.

I've successfully been able to return an entire collection via my API. Now I wish to be able to return the collection sorted by my id field.

To do this I created an index which looks like this:

{
  name: "sort_by_id",
  unique: false,
  serialized: true,
  source: "my_first_collection",
  values: [
    {
      field: ["data", "id"]
    },
    {
      field: ["ref"]
    }
  ]
}

I then was able to call this via my api and get back and array, which simply contained the ID + ref, rather than the associated documents. I also could only console log it, I assume because the resolver was expecting to be passed an array of objects with the same fields as my typedefs. I understand I need to use the ref in order to look up the documents, and here is where I'm stuck. An index record looks as follows:

[1, Ref(Collection("my_first_collection"), "352434683448919125")]

In my resolvers.js script, I am attempting to receive the documents of my sorted index list. I've tried this:

async users() {
    const response = await client.query(
            q.Map(
                q.Paginate(
                    q.Match(
                        q.Index('sort_by_id')
                    )
                ),
                q.Lambda((ref) => q.Get(ref))
            )
        )

        const res = response.data.map(item => item.data);
        return [... res]
}

I'm unsure if the problem is with how I've structured my index, or if it is with my code, I'd appreciate any advice.

It looks like you also asked this question on the Fauna discourse forums and got an answer there: https://forums.fauna.com/t/unable-to-return-a-list-of-documents-via-an-index/3511/2

Your index returns a tuple (just an array in Javascript) of the data.id field and the ref. You confirmed that with your example result

[
  /* data.id */ 1, 
  /* ref     */ Ref(Collection("my_first_collection"), "352434683448919125")
]

When you map over those results, you need to Get the Ref. Your query uses q.Lambda((ref) => q.Get(ref)) which passes the whole tuple to Get

Instead, use:

q.Lambda(["id", "ref"], q.Get(q.Var("ref")))

// or with JS arrow function 
q.Lambda((id, ref) => q.Get(ref))

or this will work, too

q.Lambda("index_entry", q.Get(q.Select(1, q.Var("index_entry"))))

// or with JS arrow function 
q.Lambda((index_entry) => q.Get(q.Select(1, index_entry)))

The point is, only pass the Ref to the Get function.