MongoError: Tailable cursor doesn't support sorting

[Matias Micenmacher]

Hi everyone,

I am new in MongoDb and Nodejs.

I am having this error: (thanks for tour help!!)

matias@dell ~/nodejs $ node nuevo.js

/home/matias/nodejs/node_modules/mongodb/lib/utils.js:97

    process.nextTick(function() { throw err; });

                                        ^

MongoError: Tailable cursor doesn't support sorting

    at Cursor.sort (/home/matias/nodejs/node_modules/mongodb/lib/cursor.js:358:37)

    at /home/matias/nodejs/nuevo.js:35:55

    at handleCallback (/home/matias/nodejs/node_modules/mongodb/lib/utils.js:95:12)

    at /home/matias/nodejs/node_modules/mongodb/lib/cursor.js:513:5

    at handleCallback (/home/matias/nodejs/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:248:5)

    at nextFunction (/home/matias/nodejs/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:638:5)

    at /home/matias/nodejs/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:563:7

    at queryCallback (/home/matias/nodejs/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:224:5)

    at Callbacks.emit (/home/matias/nodejs/node_modules/mongodb/node_modules/mongodb-core/lib/topologies/server.js:95:3)

    at null.messageHandler (/home/matias/nodejs/node_modules/mongodb/node_modules/mongodb-core/lib/topologies/server.js:246:23)

matias@dell ~/nodejs $ 

I am runing mongoDB 3.0.4 and nodejs  0.12.6 and here is my code (i have already created a chat db and a collection called "messages":

/**

 * How to subscribe for new MongoDB documents in Node.js using tailable cursor

 */

// subscriber function

var subscribe = function(){

  var args = [].slice.call(arguments);

  var next = args.pop();

  var filter = args.shift() || {};

  if('function' !== typeof next) throw('Callback function not defined');

  // connect to MongoDB

  require('mongodb').MongoClient.connect('mongodb://localhost/chat', function(err, db){

    // make sure you have created capped collection "messages" on db "test"

    db.collection('messages', function(err, coll) {

      // seek to latest object

      var seekCursor = coll.find(filter).sort({$natural: -1}).limit(1);

      seekCursor.nextObject(function(err, latest) {

        if (latest) {

          filter._id = { $gt: latest._id }

        }

        // set MongoDB cursor options

        var cursorOptions = {

          tailable: true,

          awaitdata: true,

          numberOfRetries: -1

        };

        // create stream and listen

        var stream = coll.find(filter, cursorOptions).sort({$natural: -1}).stream();

 

        // call the callback

        stream.on('data', next);

      });

    });

  });

};

// new documents will appear in the console

subscribe( function(document) {

  console.log(document);

});