$lookup Cursors in ReactiveAggregate


I have a really inefficient subscription because of several nested finds in a publishComposite .

I think this can be much more performant if converted to an Aggregate and using $lookups.

However, a regular Aggregate will only return a Cursor to the main collection it’s being called on. I will not have Reactivity for my “joined” collections in MiniMongo (rather it will just exist as data in my $project stage)

Is there anyway to get cursors for my $lookup collections too?

Update: I’m using tunguska-reactive-aggregate and it looks like it may be possible in this and in the JcBernack original.

I have a basic example below. I


Meteor.subscribe('test', parentId);

Meteor.publish('test', function (parentId) {
    const pipeline = [
      '$match': {
        '_id': parentId
    }, {
      '$lookup': {
        'from': 'Children',
        'localField': '_id',
        'foreignField': 'parentId',
        'as': 'CHILDREN'

  ReactiveAggregate(this, Parents, pipeline, {
    noAutomaticObserver: true,
    observers: [
      Parents.find({_id: parentId}),
      Children.find({parentId: parentId})

On the client I see the main Parent doc with {_id: parentId} but I still don’t get my Children docs sent over. I don’t see the cursor in the MiniMongo Explorer either. I do however see the ‘CHILDREN’ property on my main Parent Doc that gets sent over.

I’ve also tried

ReactiveAggregate(this, Parents, pipeline, {
    lookupCollections: {
        observeSelector: {parentId: parentId}

as per the original JcBernack instructions but that didn’t work either.

Edit: If I pass in the Collection Object itself into from in the $lookup instead of String 'ChildrenI get "Exception from sub test id Ai9u5eFfJ8SXhKR7r Error: cyclic dependency detected`"

I’m using SimpleSchema in both Collections and am using the Meteor default of String for _ids

I passed in debug:true and have verified that the observers are being initialized and that the pipeline gets ran. Upon debugging, error gets thrown while trying to fetch doc in a toArray. It’s an error while attempting to sanitize the doc. Then - the observers get stopped

Any insights?