graphql.js

const { ApolloServer, gql } = require("apollo-server-lambda");
var { find, filter } = require("lodash");

// Construct a schema, using GraphQL schema language
const typeDefs = gql`
  type Author {
    id: Int!
    firstName: String
    lastName: String
    """
    the list of Posts by this author
    """
    posts: [Post]
  }

  type Post {
    id: Int!
    title: String
    author: Author
    votes: Int
  }

  # the schema allows the following query:
  type Query {
    hello: String
    posts: [Post]
    author(id: Int!): Author
  }

  # this schema allows the following mutation:
  type Mutation {
    upvotePost(postId: Int!): Post
  }
`;

// // example data
const authors = [
  { id: 1, firstName: "Tom", lastName: "Coleman" },
  { id: 2, firstName: "Sashko", lastName: "Stubailo" },
  { id: 3, firstName: "Mikhail", lastName: "Novikov" }
];

const posts = [
  { id: 1, authorId: 1, title: "Introduction to GraphQL", votes: 2 },
  { id: 2, authorId: 2, title: "Welcome to Meteor", votes: 3 },
  { id: 3, authorId: 2, title: "Advanced GraphQL", votes: 1 },
  { id: 4, authorId: 3, title: "Launchpad is Cool", votes: 7 }
];

// Provide resolver functions for your schema fields
const resolvers = {
  Query: {
    hello: () => "Hello world!",
    posts: () => posts,
    author: (_, { id }) => find(authors, { id })
  }
};

const server = new ApolloServer({ typeDefs, resolvers });

const graphqlHandler = server.createHandler();

module.exports = {
  graphqlHandler
};