Aggregate cursor is undefined

[TimonKK]

I am trying this code:

var cursor = MyModel
    .aggregate([
        {
            $match: { 
                mark : "some mark" 
            }
        }
    ])
    .cursor({ batchSize: 1000 })
    .exec();

cursor.each(function(error, doc) {
  console.log('cursor each', error, doc);
});

from Mongoose API
But i have

cursor.each(function(error, doc) {
      ^
TypeError: Cannot read property 'each' of undefined

I am using

node v.0.11.14
MongoDB version 2.6.6
mongoose 4.0.5

[vkarpov15]

One of the unfortunate quirks of the .aggregate() implementation right now is that it doesn't work with buffering, so you need to do

connection.on('connected', function() {

});

to wait for mongoose to connect to the db before using the aggregation cursor :( This is something that will be improved in the future, but unfortunately something you need to work around for now.

[TimonKK]

This does not work.
If place my code in callback "mongoose.connect" - it start work.
But, if i do:

var cursor = MyModel
  .aggregate([
    {
        $match: { 
          mark : "some mark" 
        }
    }
  ])
  .cursor({ batchSize: 1000 })
  .exec(function() {
    // never cause
  });

cursor
  .on('error', function(err) {

  })
  .on('data', function(data) {

  })
  .on('end', function() {

  });

it is work too.

[vkarpov15]

Yeah another way to get it to work is in the mongoose.connect() callback. Aggregation cursor unfortunately doesn't work with buffering, so it will only start working once mongoose is connected to the db.

[timjnh]

Confirmed TimonKK's issue with on('connected') not working. This does not work with mongoose 4.0.8 and mongo 3.0.3

var schema = new mongoose.Schema(
    {
        account:  { id: Number },
        source: { id: Number },
    });

var DocumentView = mongoose.model('DocumentView', schema);

var connection = mongoose.createConnection('mongodb://localhost:27017/reporting');
connection.on('connected', function() {
    var cursor = DocumentView.aggregate()
        .allowDiskUse(true)
        .group({ _id: { sourceId: '$source.id', accountId: '$account.id' }, count: { $sum: 1 } })
        .cursor({ batchSize: 1000 })
        .exec();

    console.log(cursor);
});

cursor will be undefined. However, if you use the mongoose.connect callback it does work:

mongoose.connect('mongodb://localhost:27017/reporting', function() {

    var cursor = DocumentView.aggregate()
        .allowDiskUse(true)
        .group({ _id: { sourceId: '$source.id', accountId: '$account.id' }, count: { $sum: 1 } })
        .cursor({ batchSize: 1000 })
        .exec();

    console.log(cursor);
});

[ghost]

When adding the async cursor option I get the following error:

MongoError: cursor object can't contain fields other than batchSize

I am using:

NodeJS 4.2.4
MongoDB version 3.2.5
Mongoose 4.4.13

[vkarpov15]

@raoulwegat can you open up a separate issue with a code sample please?

[ghost]

Yes of course, here you go: #4101.

[vkarpov15]

Thanks, much appreciated

[mhombach]

I think the label "pending release" is incorrect because this was already released to my understanding?

[vkarpov15]

@mhombach yep that's incorrect, I'll fix that.