Meteor React publish merged collections - reactjs

Question

With Meteor (1.4.2.3) and React, I have the collection Objects which has an itemId which refers to the collection Items.
Currently I subscribe to the collection on the client side with:
export default createContainer(() => {
let objectsSub = Meteor.subscribe('allObjects');
var objects = Objects.find({}, {
transform: function (doc) {
doc.item = Items.findOne({
_id: doc.itemId
});
return doc;
}
}).fetch();
return {
objects: objects,
}
}, App);
This works perfect, but I think it is more elegant to merge the collections on the server side. However, none of the solutions I found seem to work
Transform at collection definition
const Objects = new Mongo.Collection('objects',
{
transform: function (doc) {
doc.item = Items.findOne({
_id: doc.itemId
})
}
});
The console gives:
Error: transform must return object
Transform at publish
if (Meteor.isServer) {
Meteor.publish('allObjects', function () {
return Objects.find({}, {
sort: { startedAt: -1 },
transform: function (doc) {
doc.item = Items.findOne({
_id: doc.itemId
});
return doc;
}
});
});
};
TypeError: Cannot read property 'name' of undefined
Where name is a property of Items

Answer 1

i usually do it in the publish like this:
Meteor.publish('allObjects', function () {
let cursor = Objects.find({}, {
sort: { startedAt: -1 });
});
let transformData = (fields) => {
fields.item = Items.findOne({
_id: fields.itemId
});
return fields;
};
let handle = cursor.observeChanges({
added: (id, fields) => {
fields = transformData(fields);
this.added('objects', id, fields);
},
changed: (id, fields) => {
fields = transformData(fields);
this.changed('objects', id, fields);
},
removed: (id) => {
this.removed('objects', id);
}
});
this.ready();
this.onStop(() => {
handle.stop();
});
}