old_contents: import DS from 'ember-data';
  
  export default DS.Model.extend({
    timestamp: DS.attr('number', {
      defaultValue () { return Date.now(); }
    }),
    name: DS.attr('string'),
    category: DS.attr('string'),
    sum: DS.attr('number')
  });
  
new_contents: import DS from 'ember-data';
  import moment from 'npm:moment';
  
  export default DS.Model.extend({
    expenses: DS.belongsTo('expenses'),
    timestamp: DS.attr('number', {
      defaultValue () { return moment(/*'2016-11-24', 'YYYY-MM-DD'*/).toDate().getTime(); }
    }),
    month: DS.attr('number', {
      defaultValue () { return parseInt(moment().format('MM')); }
    }),
    year: DS.attr('number', {
      defaultValue () { return parseInt(moment().format('YYYY')); }
    }),
    name: DS.attr('string'),
    category: DS.attr('string'),
    sum: DS.attr('number')
  });
  
subject: Set DS belongsTo for expense to contect it with expenses by date