graphql.js

// @flow

import { ApolloServer } from 'apollo-server';
import {
  GraphQLSchema,
  GraphQLObjectType,
  GraphQLString,
  GraphQLInt,
  GraphQLList,
  GraphQLNonNull,
} from 'graphql';
import { authors, articles } from './data';

const AuthorType = new GraphQLObjectType({
  name: 'Author',
  description: 'Author data',
  fields: () => ({
    id: { type: GraphQLInt },
    name: { type: GraphQLString },
  }),
});

const ArticleType = new GraphQLObjectType({
  name: 'Article',
  description: 'Article data with related Author data',
  fields: () => ({
    title: {
      type: new GraphQLNonNull(GraphQLString),
    },
    text: {
      type: GraphQLString,
    },
    authorId: {
      type: new GraphQLNonNull(GraphQLInt),
      description: 'Record id from Author table',
    },
    author: {
      type: AuthorType,
      resolve: source => {
        const { authorId } = source;
        return authors.find(o => o.id === authorId);
      },
    },
  }),
});

const Query = new GraphQLObjectType({
  name: 'Query',
  fields: {
    articles: {
      args: {
        limit: { type: GraphQLInt, defaultValue: 3 },
      },
      type: new GraphQLList(ArticleType),
      resolve: (_, args) => {
        const { limit } = args;
        return articles.slice(0, limit);
      },
    },
    authors: {
      type: new GraphQLList(AuthorType),
      resolve: () => authors,
    },
  },
});

const schema = new GraphQLSchema({
  query: Query,
});

const server = new ApolloServer({ schema });
server.listen(5000).then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});