GraphQL sample server

database.js

const { Mongoose } = require('mongoose');

let connection = null;

const connectToDB = async () => {
  const mongoose = new Mongoose();
  mongoose.Promise = global.Promise;

  let mongoUserCredentials = '';
  if (process.env.MONGO_USER && process.env.MONGO_PASSWORD) {
    mongoUserCredentials = `${process.env.MONGO_USER}:${process.env.MONGO_PASSWORD}@`;
  }

  const MONGO_URL = process.env.MONGO_URL || 'localhost:27017';
  const DB_NAME = process.env.MONGO_DB_NAME || 'sample-db';
  const MONGO_CONNECTION_STRING = `mongodb://${mongoUserCredentials}${MONGO_URL}/${DB_NAME}`;

  await mongoose.connect(MONGO_CONNECTION_STRING);
  connection = mongoose;
};

const getDB = () => {
  if (!connection) {
    throw new Error('Call connectToDB first');
  }
  return connection;
};

module.exports = {
  connectToDB,
  getDB,
};

index.js

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

import { connectToDB } from './database';

// Start the http server
const startServer = async () => {
  const { User } = require('./database/models');

  // GraphQL Types
  const typeDefs = `
    type User {
      _id: ID!
      name: String
      password: String
    }

    type Query {
      users: [User]
    }

    type Mutation {
      addUser(input: UserInput): User
    }

    input UserInput {
      name: String!
      password: String!
    }
  `;

  // GraphQL resolvers
  const resolvers = {
    Query: {
      users: async () => {
        const res = await User.find();
        return res;
      },
    },

    Mutation: {
      addUser: async(root, args) => {
        const res = await User.create(args.input);
        return res;
      },
    },
  };

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

  // Initiate express and define routes
  const app = express();
  app.use('/graphql', bodyParser.json(), graphqlExpress({ schema }));
  app.use('/', graphiqlExpress({ endpointURL: '/graphql' }));

  // Initiate the server
  app.listen(process.env.PORT || 3000, () => {
    console.log(`Server started on port: ${process.env.PORT || 3000}`);
  });
};

// Connecting to DB and then start the server
const dbConnectAndStartServer = async () => {
  try {
    await connectToDB();
    console.log('Connected to Mongo successfully');
    startServer();
  } catch (err) {
    console.error(`Error connecting to mongo - ${err.message}`);
    process.exit(1);
  }
};

// Entry point
dbConnectAndStartServer();