Custom fields, not defined in schema

Help
,
1

Apologies if this request doesn’t necessarily make sense in terms of what I should be using apollo & GQL for.

So. We have various points in our schema where there are various fields of the syntax thingId - which in turn relate to a related type, defined elsewhere in the Schema. For example, in our User objects we have:

type User {
  id
  projectId
}

Here, the User type has an associated projectId that maps to a type Project defined elsewhere in the schema.

What I’ve been hoping to achieve with apollo, is the ability to define a custom field called project, an when it exists a discreet async Query (projectById(...)) is made, returning a project for that given ID. This custom field would be given within the userById() query template, invoked from the front-end app (powered by apollo-client). So in the same User example, the front-end’s template would look like:

query userById($id: ID!) {
  userById(id: $id) {
    id
    project {
      id
      name
      # etc. etc.
    }
  }
}

I had thought perhaps resolvers were the path here, knowing they could be asynchronous and I could use their context’s dataSources to make discreet requests (and added this resolver using graphql-tools toolset) … but of course, because project isn’t part of the schema, an error is thrown. User.project defined in resolvers, but not in schema

First: am I trying to “fit a round peg in a square hole” and misusing apollo, or is there a (sane!) path towards achieving this kind of custom field definition?

Am hoping the community can help: I know that this can be achieved if I build my schema using something like type-graphql - but I really don’t want to add to the overhead of the apollo-server codebase, increase maintenance complexity - and introduce performance bottlenecks. So instead hoping for a simple solution for adding custom fields to Queries.