Express-graphql "Cannot read property 'collection' of undefined" with mongodb while runing mutation & query

Question

I am trying to query and a mutation in graph QL with express-graphql, node, and mongodb. For both the query and mutation I am getting "Cannot read property 'collection' of undefined". I go into the DB and there is a collection with documents in there. The context is there to add auth later on. I have tried multiple variations of naming the collection over the past 2 days without success. Do I need to declare a const? What am I missing?

Server.js

const express = require('express');
const graphqlHTTP = require('express-graphql');
const schema = require('./graphql/schema')
const mongoose1 = require('./mongoDB')
const expressPlayground = require('graphql-playground-middleware-express').default;
const cors = require('cors')

const Event = require('./models/events')

const app = express();

app.use(cors())

app.use(express.json());

// DB
const context = async () => {
    const db = await mongoose1;

    return { db };
};


// Provide resolver functions for your schema fields
const resolvers = {
    events: async (_, context) => {
        const { db } = await context();
        return db
            .collection('events')
            .find()
            .toArray();
    },
    event: async ({ _id }, context) => {
        const { db } = await context();
        return db.collection('events').findOne({ _id });
    },
    createEvent: args => {
        const event = new Event({
            title: args.eventInput.title,
            description: args.eventInput.description,
        })
        return event.save().then(res => {
            console.log(res);
            return { ...res._doc }
        }).catch(err => {
            console.log(err)
            throw err
        });
    }
}

app.use(
    "/graphql",
    graphqlHTTP({
        schema,
        rootValue: resolvers,
        context,
    })
);
app.get('/playground', expressPlayground({ endpoint: '/graphql' }))
app.listen(5000);

console.log(`🚀 Server ready at http://localhost:5000/graphql`); 

DB

require('dotenv').config()
const mongoose = require('mongoose');

const db = process.env.MONGODB

const mongoose1 = mongoose
    .connect(db, {
        useNewUrlParser: true,
        useCreateIndex: true,
        useUnifiedTopology: true
    }) 
    .then(() => console.log('MongoDB Connected...'))
    .catch(err => console.log(err));


module.exports = mongoose1

Schema

const { buildSchema } = require('graphql');


// Construct Schema
const schema = buildSchema(`
    type Event {
        _id: ID!
        title: String!
        description: String
        date: String

    }

    input EventInput {
        title: String!
        description: String
        date: String

    }

    type Query {
        events: [Event!]!
        event(_id: String!): Event!
    }

    type Mutation {
        createEvent(eventInput: EventInput): Event
    }
`);

module.exports = schema

Model

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const eventSchema = new Schema({
    title: {
        type: String,
        required: true
    },
    description: {
        type: String,
        required: true
    },
    date: {
        type: Date,
        default: Date.now
    }
})

module.exports = mongoose.model('Event', eventSchema)

Answer 1

The function that mongoDB.js exports returns a Promise, but that Promise resolves to undefined because console.log returns undefined. Since connect should resolve to the value of the Mongoose instance that called it, either remove the then call entirely or else make sure you return the Mongoose instance inside it.