mongoose.connect(), first argument should be String, received undefined

Question

I am trying to set the test database for the testing purpose, but its not working.

I am trying to connect to mongodb using mongoose, but finding problem in connection er

Answer 1

Since error message returned UNDEFINED uri parameter, .toString() will NOT work. You can use the String() function: String(your connection parameter).
Also, in if(env === 'test' || env === 'development') try not to use (===), it is a strict equality.

Instead try if(env == 'test' || env == 'development'). This is a loose equality. It doesn't care about the type match and will convert second operand's type to first one's type.

Answer 2

I had a similar issue, fixed by adding this code snippet.

mongoose.connect(config.DB,{ useMongoClient:true });

Answer 3

in case you've forgotten to import/require dotenv, then you can run dotenv before running your app using --require dotenv/config

node --require dotenv/config index.js // regular node command

// nodemon to restart application whenever a file gets changed
nodemon --require dotenv/config index.js

// integrate with babel-node if you're using latest JS features like import/export
nodemon --require dotenv/config index.js --exec babel-node

No need to require dotenv and call config function within codebase. Enjoy!

Answer 4

i have encountered the same error, this thread didn't help... here's my solution it was simple! im using express, mongo, mongoose, and dotENV

file 1 === db.js

 import mongoose from 'mongoose';

const connectDB =  async ()=>{

    try{
        const conn = await mongoose.connect(process.env.MONGO_URI,{
            //must add in order to not get any error masseges:
            useUnifiedTopology:true,
            useNewUrlParser: true,
            useCreateIndex: true
        })
        console.log(`mongo database is connected!!! ${conn.connection.host} `)
    }catch(error){
        console.error(`Error: ${error} `)
        process.exit(1) //passing 1 - will exit the proccess with error
    }

}

export default connectDB

file 2= server.js

import express from 'express'
import dotenv from 'dotenv'
import connectDB from './config/db.js' // DB connection
import products from './data/products.js'

dotenv.config()
const PORT = process.env.PORT || 5000
const mode = process.env.NODE_ENV

const app = express()

connectDB() //this function connects us to the DB!!!
. . . more code…

> solution: the connectDB() expression must come after the dotenv.config() expression. and that's it ! :)

Answer 5

just change the env

const db = process.env.MONGO || 'test'

Answer 6

const conn = await mongoose.connect(process.env.MONGO_URI, {
      useNewUrlParser: true,
      useUnifiedTopology: true,
      useCreateIndex: true
    })

Always put useNewUrlParser:true before putting the useUnifiedTopology:true, and then the rest.