check for required fields recursively
function validateObjectRequired(options, modelObject, entity, parents, errors) {
  for (var key in modelObject) {
    if (!modelObject[key].type && entity) {
      validateObjectRequired(
        options,
        modelObject[key],
        entity[key],
        parents + '.' + key,
        errors);
    } else if (!options.notRequired && modelObject[key].required && (!entity || !entity[key])) {
      if (!errors.notFound) errors.notFound = [];
      var fieldName = parents + '.' + key;
      errors.notFound.push(fieldName);
      errors.text.push('Field ' + fieldName + ' not found');
    }
  }

  return errors;
}