schema.ts

import { gql } from 'apollo-server-koa'
import { find, filter } from 'lodash'

const authors = [
  { id: 1, name: 'J.K. Rowling' },
  { id: 2, name: 'Michael Crichton' }
]

const books = [
  {
    title: 'Harry Potter and the Chamber of Secrets',
    author: 1,
  },
  {
    title: 'Jurassic Park',
    author: 2,
  },
];


export const resolvers = {
  Query: {
    author: (parent, args, context, info) => {
      console.log('Query.author')
      return find(authors, { id: args.id });
    }
  },
  Author: {
    books(author) {
      console.log('Author.books')
      return filter(books, { author: author.id });
    },
  }
};

export const typeDefs = gql`
  # Comments in GraphQL strings (such as this one) start with the hash (#) symbol.

  # This "Book" type defines the queryable fields for every book in our data source.
  type Book {
    title: String
    author: Author
  }

  type Author {
    id: Int
    books: [Book]
  }

  type Query {
    author(id: Int): Author
  }
`;