diff --git a/examples/parties/client/client.js b/examples/parties/client/client.js
index da20aa3fc5..d0b5e36f16 100644
--- a/examples/parties/client/client.js
+++ b/examples/parties/client/client.js
@@ -33,7 +33,7 @@ Template.details.creatorName = function () {
 };
 
 Template.details.canRemove = function () {
-  return this.owner === Meteor.userId() && attending(this) === 0;
+  return this.owner === Meteor.userId() && this.attending() === 0;
 };
 
 Template.details.maybeChosen = function (what) {
@@ -131,7 +131,7 @@ Template.map.rendered = function () {
       var selected = Session.get('selected');
       var selectedParty = selected && Parties.findOne(selected);
       var radius = function (party) {
-        return 10 + Math.sqrt(attending(party)) * 10;
+        return 10 + Math.sqrt(party.attending()) * 10;
       };
 
       // Draw a circle for each party
@@ -158,7 +158,7 @@ Template.map.rendered = function () {
       // Label each with the current attendance count
       var updateLabels = function (group) {
         group.attr("id", function (party) { return party._id; })
-        .text(function (party) {return attending(party) || '';})
+        .text(function (party) {return party.attending() || '';})
         .attr("x", function (party) { return party.x * 500; })
         .attr("y", function (party) { return party.y * 500 + radius(party)/2 })
         .style('font-size', function (party) {
diff --git a/examples/parties/model.js b/examples/parties/model.js
index 968a990440..e242a32ea7 100644
--- a/examples/parties/model.js
+++ b/examples/parties/model.js
@@ -13,7 +13,14 @@
     invited: Array of user id's that are invited (only if !public)
     rsvps: Array of objects like {user: userId, rsvp: "yes"} (or "no"/"maybe")
 */
-Parties = new Meteor.Collection("parties");
+
+Parties = new Meteor.Collection("parties", {
+  transform: function (p) {
+    p.attending = function () {
+      return (_.groupBy(this.rsvps, 'rsvp').yes || []).length;
+    };
+    return p;
+  }});
 
 Parties.allow({
   insert: function (userId, party) {
@@ -37,15 +44,11 @@ Parties.allow({
   remove: function (userId, parties) {
     return ! _.any(parties, function (party) {
       // deny if not the owner, or if other people are going
-      return party.owner !== userId || attending(party) > 0;
+      return party.owner !== userId || party.attending() > 0;
     });
   }
 });
 
-var attending = function (party) {
-  return (_.groupBy(party.rsvps, 'rsvp').yes || []).length;
-};
-
 Meteor.methods({
   // options should include: title, description, x, y, public
   createParty: function (options) {