Cannot read property 'collection' of undefined with RateLimiterMongo

[tero]

I'm implementing rate limit functionality with RateLimiterMongo and _initCollection function throws TypeError: Cannot read property 'collection' of undefined. Changing this.client.db to this.client from rows 80 and 81 will fix the issue.

This is with MongoDB version 3.4.10.

[animir]

@tero Hi, could you paste rate limiter config here and which nodejs library you use for MongoDB?

[tero]

For example this will fail. models is our internal package and models.connection is mongoose.connection.

const { RateLimiterMongo } = require('rate-limiter-flexible')
const models = require('models')

const rateLimiter = new RateLimiterMongo({
  storeClient: models.connection,
  tableName: 'rate-limits',
  points: 3, // 3 requests
  duration: 60, // per 60 seconds by IP
})

I think the problem is that this is executed immediately when module is loaded by require and connection is not established yet. mongoose.connection will pool the requests but mongoose.connection.db is not available.

[animir]

@tero Is it correct, that you use models.connection before you have established connection with mongoose? If so, what is a reason to postpone?

[animir]

@tero Which version of mongoose do you use?

[tero]

I am using Mongoose 4.13.17.

How we establish and use connection in our project is quite simple and that relies on mongoose's ability to buffer requests:

const express = require('express')
const models = require('models')
// Require routes and that means also rate limiter object is initialized.
// Because collection and indexes are created on init it will query database now
const routes = require('./routes')
const app = express()

// Connect to database. Because this is asynchronous action we can't be sure when connection is available but thanks to query buffer we don't have to worry about that.
models.connect({ mongoUrl: process.env.DB_URI })
app.use(routes)

app.listen(3000, () => console.log(`Server listening on port 3000!`))

[animir]

@tero I see now, thanks. 81 line is for mongoose support, so there is just one line should be fixed. Native driver can't buffer commands, as I know.

Would you like to make a PR?