Add a graphQL field that's the sum total of another set of fields?

[adamavenir]

I’m trying to figure out how to return a graphql field that does math across a full dataset. Basically I just want to total one specific field of all of the objects in one query.

Think: leaderboard that totals cumulative results and ranks participants by that. Imagine the following:

Dataset 1:

  {
    "contest": 1,
    "user": "sue",
    "points": 400,
  },
  {
    "contest": 1,
    "user": "bob",
    "points": 30,
  },
  {
    "contest": 2,
    "user": "sue",
    "points": 5000,
  },
  {
    "contest": 2,
    "user": "bob",
    "points": 12
  },

Dataset 2:

{
  "user": "sue",
  "image": "/images/people/sue.jpg",
  "bio": "Good at winning contests, especially compared to Bob. Look, it's just data. I'm not being mean."
}

With the goal being something like:

{
  "user": "sue",
  "image": "/images/people/sue.jpg",
  "bio": "Good at winning contests, as we've established. Keep up.",
  "totalPoints": 5400
}

What is the best way to do this in Gatsby?

I could ship all the data to the react component and do the math there, but something about that approach feels off. Maybe it's fine though?

I imagine there's a way to do this with the createResolver API but it's really not clear to me from the docs how I might do that. I'm actually kind of surprised that this use case is not a common enough one to have some obvious way of doing it.