GraphQL Schema & Resolver

import { ApolloServer } from '@apollo/server';
import { startStandaloneServer } from '@apollo/server/standalone';

const typeDefs = `#graphql
  type User {
    id: ID!
    name: String!
    email: String!
    posts: [Post!]!
  }

  type Post {
    id: ID!
    title: String!
    body: String!
    author: User!
  }

  type Query {
    users: [User!]!
    user(id: ID!): User
    posts: [Post!]!
  }

  type Mutation {
    createPost(title: String!, body: String!, authorId: ID!): Post!
  }
`;

const resolvers = {
  Query: {
    users: (_: unknown, __: unknown, { db }: Context) => db.users.findAll(),
    user: (_: unknown, { id }: { id: string }, { db }: Context) =>
      db.users.findById(id),
    posts: (_: unknown, __: unknown, { db }: Context) => db.posts.findAll(),
  },
  Mutation: {
    createPost: (_: unknown, args: CreatePostArgs, { db }: Context) =>
      db.posts.create(args),
  },
  User: {
    posts: (user: User, _: unknown, { db }: Context) =>
      db.posts.findByAuthor(user.id),
  },
  Post: {
    author: (post: Post, _: unknown, { db }: Context) =>
      db.users.findById(post.authorId),
  },
};

const server = new ApolloServer({ typeDefs, resolvers });
const { url } = await startStandaloneServer(server, { listen: { port: 4000 } });
console.log(`GraphQL ready at ${url}`);