blerg.js

function randomDeck(player, n) {
  var store = player.store;
  var deck = player.get('deck');
  var r;
  return new Ember.RSVP.Promise(function(resolve){
    store.findAll('card').then(function(cards){
      var lastIndex = cards.get('length') - 1;
      var promises = [];
      for(var i = 0; i < n; i++) {
        r = randomInt(lastIndex);
        var card = cards.objectAt(r);
        var promise = store.createRecord('deck-card', {
          card: card,
          player: player
        }).save();
        promises.push(promise);
      }

      player.save();
      Ember.RSVP.all(promises).then(function(){
        resolve();
      });
    });
  });
}