graphql-server-with-mongo.js

const express = require('express');
const graphqlHTTP = require('express-graphql');
const { MongoClient } = require('mongodb');
const {
    graphql,
    GraphQLSchema,
    GraphQLObjectType,
    GraphQLString
} = require('graphql');

const {
    PORT = 4000,
    HOST = '0.0.0.0',
    MONGO_URL = 'mongodb://localhost:27017'
} = process.env

const app = express();

const main = async () => {

    const db = await MongoClient.connect(MONGO_URL)

    var schema = new GraphQLSchema({
        query: new GraphQLObjectType({
            name: 'RootQueryType',
            fields: {
                hello: {
                    type: GraphQLString,
                    resolve(_, args, { db }) {
                        return `world with mongodb-node version ${db.topology.clientInfo.driver.version}`;
                    }
                }
            }
        })
    });

    app.use('/graphql', graphqlHTTP({
        schema,
        graphiql: true,
        context: {
            db
        }
    }));

    app.listen(PORT, HOST, () => console.log(`Graphql server started on 'http://${HOST}:${PORT}'`));
}

main()