Limiting Field Resolution

[spasarok]

Hello! I would prefer not to resolve fields the user has not requested. For example, in the GetAuthor operation below, I don't want to resolve an author's books (which come from Source A) if the user has only requested the author's name (which comes from Source B). How can I achieve this? Thanks!

type Author {
    id: Int!
    books: [Book!]
    name: String!
}

GetAuthor(id: 1) {
      name
}