CODEWITHSUNDEEP
node.jsmongodbgridfs
Hussein Menshawi
Hussein Menshawi

Reputation: 96

"Cannot read property 'once' of undefined" when using trying to use gridfs for mongodb

Im trying to use gridfs to upload files into my system. I am facing an issue in trying to connect mongodb to gridfs im only using the gridfs connection from its docs. app file :

// DB Config

const db = require("./mongoos1.js");

// Connect to MongoDB
const conn = db.connect((err) => {
    if (err) {
        console.log('unable to connect to database');
        process.exit(1);
    }

    else {
        app.listen(5000, () => {
            console.log('connected to database, app listening on port 5000');
        });
    }
});
// Init gfs
let gfs;

conn.once('open', () => {
  // Init stream
  gfs = Grid(conn.db, mongoose.mongo);
  gfs.collection('uploads');
});

Mongoose file:

const MongoClient = require('mongodb').MongoClient;
const ObjectID = require('mongodb').ObjectID;
const dbname = "FYP";
const url = "mongodb://localhost:27017/FYP";
const mongoOptions = { useNewUrlParser: true };

const state = {

    db: null
};


const connect = (cb) => { // connect method
    if (state.db) //if there is connection
        cb();
    else { // if there isn't
        MongoClient.connect(url, mongoOptions, (err, client) => { // we use mongoclient to connect
            if (err)
                cb(err);
            else {
                state.db = client.db(dbname); // if no error , set state
                cb();
            }
        });
    }
}



module.exports = { connect }; //exposing methods

am i making a mistake somewhere?

Upvotes: 0

Views: 2643

Answers (1)

noitse
noitse

Reputation: 1045

mongoDB connection is not the same as connection that is returned from createConnection

  1. .createConnection() returns a Connection instance
  2. .connect() returns the global mongoose instance

You should connect your event handler to the connection as returned by createConnection(), and not to mongoose.connection

Or move your code from 'once open' inside .connection() callback function.

Upvotes: 2

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