server.js

// # Posts and Authors example from graphql-tools docs
// This project was created with [Apollo Launchpad](https://launchpad.graphql.com)
// You can see the original pad at [https://launchpad.graphql.com/1jzxrj179](https://launchpad.graphql.com/1jzxrj179)

import { find, filter } from 'lodash';
import { makeExecutableSchema } from 'graphql-tools';
import express from 'express';
import { graphqlExpress, graphiqlExpress } from 'apollo-server-express';
import bodyParser from 'body-parser';
import cors from 'cors';

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 Apollo', votes: 3 },
  { id: 3, authorId: 2, title: 'Advanced GraphQL', votes: 1 },
  { id: 4, authorId: 3, title: 'Launchpad is Cool', votes: 7 }
];

const typeDefs = `
  type Author {
    id: Int!
    firstName: String
    lastName: String
    posts: [Post] # the list of Posts by this author
  }

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

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

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

const resolvers = {
  Query: {
    posts: () => posts,
    author: (_, { id }) => find(authors, { id })
  },
  Mutation: {
    upvotePost: (_, { postId }) => {
      const post = find(posts, { id: postId });
      if (!post) {
        throw new Error(`Couldn't find post with id ${postId}`);
      }
      post.votes += 1;
      return post;
    }
  },
  Author: {
    posts: author => filter(posts, { authorId: author.id })
  },
  Post: {
    author: post => find(authors, { id: post.authorId })
  }
};

const schema = makeExecutableSchema({
  typeDefs,
  resolvers
});

const PORT = 1337;
const server = express();

server.use(
  '/graphql',
  cors(),
  bodyParser.json(),
  graphqlExpress(() => ({
    schema
  }))
);

server.use(
  '/graphiql',
  graphiqlExpress({
    endpointURL: '/graphql',
    query: `query PostsForAuthor {
  author(id: 1) {
    firstName
    posts {
      title
      votes
    }
  }
}

mutation UpvotePost {
  upvotePost(postId: 1) {
    id
    votes
  }
}`
  })
);

server.listen(PORT, () => {
  console.log(
    `GraphQL Server is now running on http://localhost:${PORT}/graphql`
  );
  console.log(`View GraphiQL at http://localhost:${PORT}/graphiql`);
});