old_contents: import DS from "ember-data";
  
  var attr = DS.attr;
  
  var Contest = DS.Model.extend({
    title             : attr('string'),
    description       : attr('string'),
    startTime         : attr('number'),
    duration          : attr(),
    alreadyRegistered : attr('number'),
  
    problems          : DS.hasMany('problem', {async : true})
  });
  
  export default Contest;
  
new_contents: import DS from "ember-data";
  
  var attr = DS.attr;
  
  var Contest = DS.Model.extend({
    author            : attr('string'),
    title             : attr('string'),
    description       : attr('string'),
    createdAt         : attr('string'),
    updatedAt         : attr('string'),
    startTime         : attr('number'),
    duration          : attr(),
    alreadyRegistered : attr('number'),
  
    problems          : DS.hasMany('problem', {async : true})
  });
  
  export default Contest;
  
subject: Add more attributes to contest's model