Meteor Reactive Joins

https://www.discovermeteor.com/blog/reactive-joins-in-meteor/

Use this package

https://github.com/peerlibrary/meteor-reactive-publish

Meteor.publish('subscribed-posts', function () {
  this.autorun(function (computation) {
    var user = User.findOne(this.userId, {fields: {subscribedPosts: 1}});

    return Posts.find({_id: {$in: user && user.subscribedPosts || []}});
  });
});