Using underscore.js groupBy with Ember.js

ember.js, underscore.js

Solution

You could implement your own `groupBy` function tailored for ember-data DS-ManyArray objects and extend `_` with it:

_.emberArrayGroupBy = function(emberArray, val) {
  var result = {}, key, value, i, l = emberArray.get('length'),
      iterator = _.isFunction(val) ? val : function(obj) { return obj.get(val); };

  for (i = 0; i < l; i++) {
    value = emberArray.objectAt(i);
    key   = iterator(value, i);
    (result[key] || (result[key] = [])).push(value);
  }
  return result;
};

Now you can call

var grouped = _.emberArrayGroupBy(activities, function(activity) {
  return activity.get('dateLabel');
});

or more simply

var grouped = _.emberArrayGroupBy(activities, 'dateLabel');

The function above is based on underscore's original `groupBy()` implementation, which looks very similar:

_.groupBy = function(obj, val) {
  var result = {};
  var iterator = _.isFunction(val) ? val : function(obj) { return obj[val]; };
  each(obj, function(value, index) {
    var key = iterator(value, index);
    (result[key] || (result[key] = [])).push(value);
  });
  return result;
};

Problem

Is it possible to use underscore's groupBy function with ember.js? I have the following attempt which is obviously not working: ``` var activities = App.store.findMany(App.Activity, feed.mapProperty('id').uniq()) var grouped = _.groupBy(activities, function(activity){ return activity.get('dateLabel;') }); ``` I get the following error: Object App.Activity has no method 'get' The store is loaded with the correct data so findMany will not make a remote call. The problem is that findMany returns a DS.ManyArray which is probably a lot different than what _.groupBy is looking for.

Original source