mongodb 'sort' not working if 'limit' is removed

Question

I'm new with mongodb and I was trying sort option by refering : http://mongodb.github.io/node-mongodb-native/markdown-docs/queries.html#sorting

My code:

MongoClient.connect('mongodb://127.0.0.1/test', function (err, db) { //connect to mongodb   
    var collection = db.collection('qr');
    var options = {
        "limit": 20,
        "sort": "CARDNO"
    }
    collection.find({}, options).toArray(function (err, data) {
        console.log(data.length);
        res.send(JSON.stringify(data));
    });
    console.log("successfully connected to the database");
    //db.close();
});

Returns first 20 records of sorted result.

But when I remove the "limit"

MongoClient.connect('mongodb://127.0.0.1/test', function (err, db) { //connect to mongodb   
    var collection = db.collection('qr');
    var options = {
        "sort": "CARDNO"
    }
    collection.find({}, options).toArray(function (err, data) {
        console.log(data.length);
        res.send(JSON.stringify(data));
    });
    console.log("successfully connected to the database");
    //db.close();
});

I'm getting error

I tried

console.log(err)

It's giving [Error: parseError occured] in the console

/home/local/user/Desktop/node10k/routes/user.js:23
                console.log(data.length);
                                ^
TypeError: Cannot read property 'length' of null

Note: My collection contains 84k records.

My issue: It's working fine if I put some limit, I tried up to 64k limit its working when I try 74k I'm getting issue [Error: parseError occured]

Result for "limit" : 64020

Express server listening on port 3000
successfully connected to the database
64020
GET /users 200 11735ms - 15.32mb

Result for "limit" : 74020

Express server listening on port 3000
successfully connected to the database
[Error: parseError occured]

Why am I getting error when "limit" is beyond 64k?

Neil notified me in a comment:

1. Code had syntax issue
2. It may be cause of issue with toArray

Answers:

1. I got the code referring the mongodb page(Link given at the starting) So this is not a syntax issue its working fine with my code if limit is give. So not a Syntax error

2. I tried

   collection.find().toArray(function (err, data) { if (err) { console.log(err); } else { console.log(data.length) } res.send(JSON.stringify(data)); });

And I'm getting result with no error.

Express server listening on port 3000
successfully connected to the database
84050
GET /users 200 17525ms - 20.1mb

So not a toArray() issue

This issue only comes with sort and the code is working fine with 64k Data. Why?

Answer 1

Your sort was never working in the first example. The syntax is wrong

var options = {
   "sort": { "CARNO": 1 }
};

Or -1 for descending.

Also, not the problem but I have seen you do the same on another question, you don't json.stringify the err, just log it to console. And then you would have seen what you have done wrong.

The following usage works just fine, so if you are not getting a result then you are doing something different to how it is presented here:

var MongoClient = require('mongodb').MongoClient;

MongoClient.connect('mongodb://127.0.0.1/test', function (err, db) {

  var collection = db.collection('stuff');

  var options = {
    "sort": { "duration": -1 },
  };
  collection.find({},options).toArray(function(err, data) {
    if (err) {
      console.log(err);
    }
    console.log(data);
  });

});

You can also chain the .sort() to the find before .toArray() if this still eludes you.