Alternate _publishCursor for Meteor

publishCursor.js

// Meteor extension to allow modifications to documents when publishing.
// Also allows specifying an alternate name under which to publish the
// collection, using "sub_name".

_.extend(Meteor._LivedataSubscription.prototype, {
	_publishCursor: function (cursor, name) {
		var self = this;
		var collection = name || cursor.sub_name || cursor.collection_name;
		var map_callback = cursor.map_callback || function (obj) { return obj; };

		var observe_handle = cursor.observe({
			added: function (obj) {
				var mod_obj = map_callback.call(self, obj);
				if (mod_obj === false) {
					self.unset(collection, obj._id, _.keys(obj));
				} else {
					self.set(collection, mod_obj._id, mod_obj);
				}
				self.flush();
			},
			changed: function (obj, old_idx, old_obj) {
				var set = {}, mod_obj = map_callback.call(self, obj);
				if (mod_obj === false) {
					self.unset(collection, obj._id, _.keys(obj));
				} else {
					_.each(mod_obj, function (v, k) {
						if (!_.isEqual(v, old_obj[k])) {
							set[k] = v;
						}
					});
					self.set(collection, mod_obj._id, set);
					var dead_keys = _.difference(_.keys(old_obj), _.keys(mod_obj));
					self.unset(collection, mod_obj._id, dead_keys);
				}
				self.flush();
			},
			removed: function (old_obj, old_idx) {
				var mod_old_obj = map_callback.call(self, old_obj);
				if (mod_old_obj !== false) {
					self.unset(collection, mod_old_obj._id, _.keys(mod_old_obj));
					self.flush();
				}
			}
		});

		self.complete();
		self.flush();

		self.onStop(_.bind(observe_handle.stop, observe_handle));
	}
});

Don't use this =) Meteor has come a long way since, and so has my understanding of how Meteor works. If you find yourself needing this code, you may be doing something wrong.

@matb33 ... I am having to publish a modified cursor. Any suggested way you have identified to do this?

This is very helpful when you may have data collision or you want to track the data subscription origin in a components model.