DS.Errors#errorsFor()

Returns errors for a given attribute

var user = store.createRecord('user', {
  username: 'tomster',
  email: 'invalidEmail'
});
user.save().catch(function(){
  user.get('errors').errorsFor('email'); // returns:
  // [{attribute: "email", message: "Doesn't look like a valid email."}]
});