dynamicSubscriptions.js

Kids = new Meteor.Collection('kids');
Parents = new Meteor.Collection('parents');

if (Meteor.isClient) {
  Template.hello.kids = function () {
    return Kids.find();
  };

  Meteor.startup(function(){
    Meteor.subscribe('parents');

    Deps.autorun(function() {
      parent = Parents.findOne();
      console.log("Found parent", parent);
      if (!parent) return;
      Meteor.subscribe('kids', parent._id); // CHANGED here by Ze Jibe
    });
  });

}

if (Meteor.isServer) {
  Meteor.startup(function () {
    Meteor.publish('parents', function() {
      return Parents.find();
    });

    Meteor.publish('kids', function (parentId) {  // CHANGED here by Ze Jibe
      var parent = Parents.findOne({ _id: parentId });  // CHANGED here by Ze Jibe
      if (!parent) return;  // CHANGED here by Ze Jibe
      return Kids.find({ _id: { $in: parent.childrenIds } });
      //return Kids.find();
    });
  });

  Meteor.startup( function(){
    Parents.remove({});
    Kids.remove({});
    parentId = Parents.insert({name:'alfred', childrenIds:[]});
    console.log("Inserted parentId", parentId);

    kid1Id = Kids.insert({name:'fred'});
    Parents.update(parentId, {$push: {childrenIds:kid1Id}});
    console.log("After first push, parent is", Parents.findOne());

    kid2Id = Kids.insert({name:'george'});

    Meteor.setTimeout(function() {
      Parents.update(parentId, {$push: {childrenIds:kid2Id}});
      console.log("After second push, parent is", Parents.findOne());
    }, 10*1000);
  });
}