MongoStore: Cannot Init Client. Not accepting mongoose connection object

Question

I am trying to use an AWS DocumentDB (AWS-branded MongoDB) to help me store session data. I've already got a successful connection, with mongoose, to the database in my db.js file.

When I try to pass this mongoose connection to the as the mongooseConnection parameter in my MongoStore constructor, I get the following error:

Assertion failed: You must provide either mongoUrl|clientPromise|client in options
xxxx/node_modules/connect-mongo/build/main/lib/MongoStore.js:119
            throw new Error('Cannot init client. Please provide correct options');
                  ^

Error: Cannot init client. Please provide correct options

My db.js looks like this:

import * as fs from 'fs';
import mongoose from 'mongoose';

var ca = [fs.readFileSync("./certs/rds-combined-ca-bundle.pem")];  // AWS-provided cert

var connectionOptions = {
    useUnifiedTopology: true,
    useNewUrlParser: true,
    ssl: true,
    sslValidate: true,
    checkServerIdentity: false,
    sslCA: ca,
    replicaSet: 'rs0',
    readPreference: 'secondaryPreferred',
    retryWrites: false
};

var connectionString = 'mongodb://' + user + ':' + pwd + '@' + dbServerLocation + '/' + dbName;  // variables defined elsewhere and removed from this post.

mongoose.connect(connectionString, connectionOptions)
    .catch((err) => console.log(err));
}

export default mongoose.connection;

and my server.js (main) that is throwing the error looks like this:

import db from './db/db.js';
import session from 'express-session';
import MongoStore from 'connect-mongo';

db.on('error', () => console.error('MongoDB connection error.'));
db.on('reconnectFailed', () => console.error("Reconnection attempts to DB failed."));
db.on('connected', () => { console.log('Connected to DocumentDB database in AWS') });

import express from 'express';

const sessionStore = new MongoStore({
    mongooseConnection: db,
    collection: 'sessions'
})

var app = express();
app.use(session({
    resave: false,
    secret: 'secret word',
    saveUninitialized: true,
    store: sessionStore,
    cookie: {
        maxAge: 1000 * 60 * 60 * 24
    }
}))

... and the rest of the app.

What do I need to change in order to be able to use my mongoose connection object as the session store?

I have looked elsewhere but questions like this indicate we should be able to send the actual mongoose connection rather than re-sending the connection string and doubling up on connections: Error: Cannot init client | mongo-connect express-session

Answer 1

Turns out the mongooseConnection parameter to the MongoStore constructor has been changed to 'client' per the documentation here: https://www.npmjs.com/package/connect-mongo

(I still get errors - specifically now I'm getting a 'con.db' is not a function from MongoStore ... but as it relates to the OP, the answer is to change to 'client' instead of 'mongooseConnection'.)

For those coming after me - specifically those that think they have a mongo connection and want to pass it as the client parameter.... you'll need to invoke the getClient() function to help make that happen - like this:

const sessionStore = new MongoStore({
    client: dbConnection.getClient(),
    collectionName: 'sessions'
})

Found this in the migration wiki for connect-mongo here: https://github.com/jdesboeufs/connect-mongo/blob/HEAD/MIGRATION_V4.md

Answer 2

Here's how I set mine up using this method: https://github.com/jdesboeufs/connect-mongo/blob/092066300746f3733c0c3dac8cc378407ef5a26c/example/mongoose.js

Works for me. Key thing that ended up doing the trick was also changing 'localhost' to '127.0.0.1' if you are using Compass

const express = require('express');
const mongoose = require('mongoose');
const session = require('express-session');
const MongoStore = require('connect-mongo')

const app = express()
const port = 3000

const dbString = 'mongodb://127.0.0.1:27017';
const dbOptions = { 
    useNewUrlParser: true,
    useUnifiedTopology: true
}

const conn = mongoose.connect(dbString, dbOptions).then(m => m.connection.getClient());


app.use(express.json());
app.use(express.urlencoded({extended: true}));

const sessionStore = MongoStore.create({
    clientPromise: conn,
    dbName: "session"

})

app.use(session({
    secret: 'some secret',
    resave: false,
    saveUninitialized: true,
    store: sessionStore,
    cookie: {
        maxAge: 1000 * 60 * 60 * 24
    }
}))

app.get('/', (req, res, next) => {
    res.send('<h1>Hello Bret (sessions)</h1>')
});

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})