How to reactively aggregate mongodb in meteor

Question

I am newbie to meteor. I had established the publish / subscribe concept. I am facing the following error while performing aggregation reactively.

client code :

Answer 1

You don't have a client side collection. Also, you need to subscribe before you call this helper.

Try this

import { Template } from 'meteor/templating';
import { ReactiveVar } from 'meteor/reactive-var';
import './main.html';

var clientReport = new Mongo.Collection('clientReport');

Meteor.subscribe("reportTotals");

Template.header.helpers({
    'tasks': function () {
        console.log("tasks helper called : ");     
        console.log(clientReport.find().fetch());
    },   
});

You also don't need the pipeline and no autorun on server code, try this:

AtmData = new Mongo.Collection('atmdata');

Meteor.startup(() => {
  // code to run on server at startup
/*     AtmData.insert({
        bottles_used: 123,
    }); */

});



Meteor.publish("reportTotals", function() {
// Remember, ReactiveAggregate doesn't return anything

    ReactiveAggregate(this, AtmData, [{
        // assuming our Reports collection have the fields: hours, books    
        $group: {
            '_id': null,
            'bottles_used': {
            // In this case, we're running summation. 
                $sum: '$bottles_used'
                // $sum: 1
            }
        }
        }], { clientCollection: "clientReport" });    
});

Answer 2

I made an NPM package here: meteor-publish-join. Its main purpose is to publish expensive-aggregated values after a certain amount of time. Hope it will help in your case.