ejs返回空数组，但console.log返回一个值

Question

我有一个在console.log（）中返回的变量，但在渲染时返回一个空数组。

function loadFestival(festSlug) {
  return Q.Promise(function(resolve, reject, notify) {
    Collection.findOne({
      slug: festSlug
    }).deepPopulate('events shows')

    .exec(function(err, model) {
      if (err) {
        return reject(err);
      }
      if (!model) {
        return reject(new Error('Festival not found for slug: ' + festSlug));
      }

      var show_performances = [];

      model.shows.forEach(function(show) {
        var showID = show._id.toString();



        show_performances[showID] = []
        show_performances[showID]['performances'] = [];
        show_performances[showID]['ticketing'] = [];

        model.events.forEach(function(event) {
          if (show._id.toString() == event.show.toString()) {
            show_performances[showID]['performances'].push(moment(event.dateRange.start).format('YYYY MMM D'));
            show_performances[showID]['ticketing'][moment(event.dateRange.start).format('YYYY MMM D')] = event.ticketing_url;
          }
        });
      });
      resolve(show_performances);
    });
  });
}

来自评论：

//Here is the code running 
loadFestival('slug').then(function(model) {
  console.log(model) //returns as should be 
  res.render('.//index.html', {
    layout: layout,
    model: JSON.stringify(model) // returns nothing 
  });
});

上面的代码应该在console.log（show_performances）中返回，但是当渲染时没有返回。感谢。