PostType = GraphQL::ObjectType.define do
  name "Post"
  
  field :comments, !types[!CommentType] do
    preload comments: :author
    resolve -> (post, args, ctx) { post.comments }
  end
  
  # Or you can use the more terse syntax:
  field :comments, !types[!CommentType], preload: { comments: :author }, property: :comments
end