how to get form data and query mongodb in node js

Question

I am trying to fetch form data, query database and find number of documents that are related to that data, and console that count (for simplicity).

app.post('/process_get', function(req, res){
    response = {
        first_name : req.body.first_name,
        last_name : req.body.last_name,
        gender: req.body.gender
        };
    dbConn.then( function (db) {
        var dbo = db.db("azima");
        var count = dbo.collection('users').find({first_name: req.body.first_name}, {gender: req.body.gender}).count();
        console.log(count);
    });

    console.log(response);

    //convert the response in JSON format
    res.end('Data received:\n' + JSON.stringify(req.body));
});

But I'm getting following:

Example app listening at http://:::8888
{ first_name: 'Najar Man', last_name: 'Malakar', gender: 'Male' }
Promise { <pending> }

I know this is because of asynchronous nature, but I don't know how to perform this "simple" operation, since I am new to node.js and mongodb.

How do I store the count value to variable properly?

count is probably a promise, so you have to deal with it the same way you do with dbConn, await it, or use .then on it... — Luca Kiebel
– Luca Kiebel, Commented Sep 21, 2018 at 15:06

Rajan Lagah · Accepted Answer · 2018-09-21 15:26:33Z

1

If you are using latest technologies. Use async/await.

   app.post('/process_get',function(req, res){
        response = {
            first_name : req.body.first_name,
            last_name : req.body.last_name,
            gender: req.body.gender
            };
    dbConn.then( function (database) {
            var dbo = database.db("azima");
            var count
   dbo.collection('users').find({first_name: req.body.first_name}, 
                                 {gender: req.body.gender})
                                 .count(function(err,resCount){
                                  if(err){
                                    console.log(err)}
                                  else{
                                    count = resCount  
                                    console.log(count);
            res.end('Data received:\n' + JSON.stringify(req.body));
                   }
                 });

    }).catch(function(e){console.log(e)})

    console.log(response);

    //convert the response in JSON format
});

Try to add this if okay then okay else try to share what is in catch block More over when you will send data from mongo query then you will need to put res.send inside the dbConn.then else it will not wait for mongodb query and you will send

edited Sep 21, 2018 at 15:26

answered Sep 21, 2018 at 15:17

Rajan Lagah

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3 Comments

Azima Over a year ago

I'm getting Unexpected identifier error pointing to the line await. Also tried async/await

Azima Over a year ago

@Razan: can you elaborate to me on a callback function on count()? that'd be great!

Rajan Lagah Over a year ago

@Azima Let me try .count() will give us 2 output error or result. So we take that in function(callback) that we have written and in that function we have check if error is defined(i.e if .count() throw error ) then we we set some action else we perform something else

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