why can't I insert object into mongodb by using node.js?

Question

    var express = require('express');
    var routes = require('./routes');
    var socket = require('socket.io');
    var fs = require('fs');
    var app = module.exports = express.createServer();
    var Server = require('mongodb').Server,
        Db = require('mongodb').Db,
        Connection = require('mongodb').Connection;
    var host = 'localhost';
    var port = Connection.DEFAULT_PORT;
    var db = new Db('node-mongo-examples', new Server(host, port, {}), {native_parser:false});

    db.open(function(err, db) {
        console.log('opened');   
        app.listen(3000); 

    });


    db.collection('locations', function(err, collection) {
          var object= {word:'TEST'};
          collection.insert(object, {safe:true}, function(err, result) {
            var array = collection.findOne({word:'TEST'}, function(err, item) {});            
             console.log(array);// <----always  "undefined" 
          });        
    });

I try to insert the object into the database. And by using "console.log(array)" everytime,I find that it always be "undefined". Is it can't be insert into the database or can't be found from the database. How can I solve it??

But, The 'console.log(item)' shows 'null'. So does it sucessfully insert into the database, or should I change another way to get the object from database.

Michelle Tilley · Accepted Answer · 2012-08-14 03:42:24Z

2

collection.findOne is asynchronous, so you don't use the return value of the function; instead, you should console.log(item) from inside your (currently empty) callback.

 db.collection('locations', function(err, collection) {
     var object= {word:'TEST'};
     collection.insert(object, {safe:true}, function(err, result) {
       collection.findOne({word:'TEST'}, function(err, item) {
          console.log(item);
       });
     });        
 });

answered Aug 14, 2012 at 3:42

Michelle Tilley

159k40 gold badges379 silver badges312 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

MaryHo Over a year ago

May I ask ..... The item is empty now. How should I add a call back in that findone function.

Collectives™ on Stack Overflow

why can't I insert object into mongodb by using node.js?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related