new_contents: from wtforms.validators import ValidationError
  
  
  def db_match(model, message, *args, **kwargs):
      fields = kwargs.pop('match_fields', None)
      result = model.query.filter_by(*args, **kwargs).first()
      if result is None:
          raise ValidationError(message)
      if fields is not None:
          for key in fields:
              if (not hasattr(result, key) or
                      result.key != fields[key]):
                  raise ValidationError(message)
  
subject: Add custom validator for matching db fields