I am getting error on submitting the form - node.js

Question

While connecting to mongodb, I am getting a warning
"DeprecationWarning: current URL string parser is deprecated, and will
be removed in a future version. To use the new parser, pass option {
useNewUrlParser: true } to MongoClient.connect."
while submitting the form - I am getting
The database connection must be open to store files
at GridFSStorage._handleFile (C:\Users\charan puli\Desktop\upload\node_modules\multer-gridfs-storage\lib\gridfs.js:341:17)
at C:\Users\charan puli\Desktop\upload\node_modules\multer\lib\make-middleware.js:144:17
at allowAll (C:\Users\charan puli\Desktop\upload\node_modules\multer\index.js:8:3)
at wrappedFileFilter (C:\Users\charan puli\Desktop\upload\node_modules\multer\index.js:44:7)
at Busboy. (C:\Users\charan puli\Desktop\upload\node_modules\multer\lib\make-middleware.js:114:7)
at Busboy.emit (events.js:182:13)
//////////////////app.js///////////////////////
//middle wares
app.use(bodyparser.json())
app.use(methodOverride('_method'))
app.set("view engine","ejs")
//connection
var mongoURI='mongodb+srv://user:password#clusterpuli-xs9yc.mongodb.net/test?retryWrites=true'
mongoose.connect(mongoURI,{useNewUrlParser:true})
.then(()=>{console.log('connected successfully');
})
.catch(err=>{console.log(err);
})
var conn=mongoose.connection
var gfs
conn.once('open',() =>{
gfs = Grid(conn.db, mongoose.mongo);
gfs.collection('questions')
})
//create storage object
var storage = new GridFsStorage({
url: mongoURI,
file: (req, file) => {
return new Promise((resolve, reject) => {
crypto.randomBytes(16, (err, buf) => {
if (err) {
return reject(err);
}
const filename =buf.toString('hex')+path.extname(file.originalname);
const fileInfo = {
filename: filename,
bucketName: 'questions'
};
resolve(fileInfo);
});
});
}
});
const upload = multer({ storage });
//#route /upload POST
app.post('/upload',upload.single('file'),(req,res)=>{
res.json({'file':req.file})
})
var port= 3000
app.get("/",(req,res)=>{
res.render('index')
})
app.listen(port,()=>{
console.log(`app is running at ${port}`);
})
////////////////////////////////////
expected - json file object, connected Successfully
actual - database connection must be open

Answer 1

This should work for you, I have tested it:
//connection
const mongoURI = 'mongodb+srv://user:password#clusterpuli-xs9yc.mongodb.net/test?retryWrites=true';
const promise = mongoose.connect(mongoURI, { useNewUrlParser: true });
const conn = mongoose.connection;
let gfs;
conn.once('open',() => {
gfs = Grid(conn, mongoose.mongo);
gfs.collection('questions');
});
//create storage object
const storage = new GridFsStorage({
db: promise,
file: (req, file) => {
return new Promise((resolve, reject) => {
crypto.randomBytes(16, (err, buf) => {
if (err) {
return reject(err);
}
const filename = buf.toString('hex') + path.extname(file.originalname);
const fileInfo = {
filename: filename,
bucketName: 'questions'
};
resolve(fileInfo);
});
});
}
});
const upload = multer({ storage });
See this reference here for further information:
Multer's GridFS storage engine
It has to do with the new url parser of the new mongo client of the Node.js MongoDB Driver API. See this reference: MongoClient
I had the same issue that's why I ended up on your question.

Answer 2

//connection
var mongoURI='mongodb+srv://charanpuli:Charan#1999#clusterpuli-xs9yc.mongodb.net/test?retryWrites=true'
var conn = mongoose.connection
MongoClient.connect(db, { useNewUrlParser: true })
.then(()=>{console.log('connected successfully');
})
.catch(err=>{console.log(err);
})
var gfs
conn.once('open',() =>{
gfs = Grid(conn.db, mongoose.mongo);
gfs.collection('questions')
})