Loop through an HTTP response object and only add new Alloy Models if needed.

Alloy.Model.HTTP.Loop

/*

  Loop through an HTTP response object and only add new Alloy Models if needed.
  Assumes `eventId` is the primary key defined in Events.js Model file.
  
  Caution: this snippet is untested

*/

var events = Alloy.createCollection('Events');

// Optional: Calling reset() without passing any models as arguments will empty the entire collection.
events.reset();

// Loop through HTTP results
_.each(response.results, function(element, index, list) {
  
  Ti.API.info(element.eventId);
  
  mdl = Alloy.createModel(element);
  // If the model does not yet have an id, it is considered to be new. Could also leverage mdl.hasChanged()
  if (mdl.isNew()) {
    mdl.save({
      success: function() {}
      error: function(){}
    });
  }

});

// After persisting, hydrate the collection (invoking UI binding)
events.fetch();