Plugin - Where to get field type for a query?

I’m trying to write a server plugin that uses an executionDidStart event to recurse through a query and do something for each field in it before Apollo resolves the query. However, I need to look up the GraphQL type of each selected field, and I can’t see anywhere in the apiSchema, the _typeMap or the document itself that provides this info. For example, let’s say this was my typedef file:

type User {
    name: String!
type Post {
    text: String!
    author: User
type Query {
    posts: [Post]

And let’s say this query came in:

query GetStuff {
  posts {
    author {

I need to be able to know that query->posts is of type Post, and query->posts->author is of type User. Is there anywhere Apollo Server exposes this, or do I have to re-parse the typedef myself?

Thanks very much, I’d be very grateful for any help you could give. :pray: