GraphQL Demo

.nvmrc

10.6.0

data.json

{
  "users": [
    {
      "id": 1,
      "name": "John",
      "email": "john@foo.com",
      "address": 4
    },
    {
      "id": 2,
      "name": "Jane",
      "email": "jane@foo.com",
      "address": 5
    },
    {
      "id": 3,
      "name": "Bob",
      "email": "bob@foo.com",
      "address": 5
    }
  ],
  "addresses": [
    {
      "id": 4,
      "house_number": "1",
      "street": "First Street",
      "city": 6
    },
    {
      "id": 5,
      "house_number": "2",
      "street": "Second Street",
      "city": 7
    }
  ],
  "cities": [
    {
      "id": 6,
      "name": "Boston",
      "state": "MA"
    },
    {
      "id": 7,
      "name": "New York",
      "state": "NY"
    }
  ]
}

index.js

const { graphql } = require('graphql');
const schema      = require('./schema');

const log = x => console.log( JSON.stringify( x, null, 2 ) );

const query = `{
  user(id:2) {
    id,
    name,
    email,
    address {
      id,
      house_number,
      street,
      users {
        id,
        name
      },
      city {
        id,
        name,
        state
      }
    }
  }
}`;

graphql( schema, query ).then( log );

package.json

{
  "name": "graphql-demo",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "dataloader": "^1.4.0",
    "graphql": "^14.0.2",
    "graphql-tools": "^3.1.1"
  }
}

resolvers.js

const { users, addresses, cities } = require('./data');
const DataLoader                   = require('dataloader');

const userLoader = new DataLoader(
  async keys => users.filter( d => keys.includes( d.id ) )
);

const addressLoader = new DataLoader(
  async keys => addresses.filter( d => keys.includes( d.id ) )
);

const cityLoader = new DataLoader(
  async keys => cities.filter( d => keys.includes( d.id ) )
);

module.exports = {

  Query: {

    async user( root, { id } ) {
      return userLoader.load( id );
    },

    async users() {
      return [ ...users ];
    }

  },

  User: {

    async address({ address }) {
      return addressLoader.load( address );
    }

  },

  Address: {

    async city({ city }) {
      return cityLoader.load( city );
    },

    async users({ id }) {
      return users.filter( d => d.address === id );
    }

  }

};

schema.graphql

type Query {
  user(id: Int!): User,
  users: [ User ]
},

type User {
  id: Int,
  name: String,
  email: String,
  address: Address
},

type Address {
  id: Int,
  house_number: String,
  street: String,
  city: City,
  users: [ User ]
}

type City {
  id: Int,
  name: String,
  state: String
}

schema {
  query: Query
}

schema.js

const fs                       = require('fs');
const resolvers                = require('./resolvers');
const { makeExecutableSchema } = require('graphql-tools');

const typeDefs = fs.readFileSync( 'schema.graphql', 'utf8' );

module.exports = makeExecutableSchema({ typeDefs, resolvers });