What is the correct way to save records in Embah?

gistfile1.txt

//1.
WeekPresence.get('transaction').commit();

//2.
WeekPresences.pushObject(WeekPresence);

//3.
var WeekPresence = Haps.WeekPresence.createRecord({ 
  monday: this.set('model.monday', value),
  tuesday: this.get('model.tuesday'),
  /...

});


//4. 
App.store.commit();