Where to extend collection documents with computed fields in Meteor?

Question

We have information we need on the client which is computed on a document. Like for example the number of entries in an array.

More practically we have a document Workshop which helds an array of participants (user's _id). Now we want the Workshop.numberOfParticipants().

There is no need to transmit the whole array to the client, so where to calculate this value? Is it possible to add this value to the document "Workshop" as a field like the other data?

I like to circumvent the generation of a Template.workshop.numberOfParticipants().

Answer 1

One option for the future is MongoDB's oddly-named aggregation framework. Queries written against the aggregate API can return documents with calculated fields.

Meteor core doesn't support aggregate queries yet, but it's on the wishlist.