Extract a SQLAlchemy model instance to a dictionary
    :param model: the model to be extracted
    :param exclude: Any keys to be excluded
    :return: New dictionary consisting of property-values

def model_to_dict(model, exclude=None):
    """
    Extract a SQLAlchemy model instance to a dictionary
    :param model: the model to be extracted
    :param exclude: Any keys to be excluded
    :return: New dictionary consisting of property-values
    """
    exclude = exclude or []
    exclude.append('_sa_instance_state')
    return {k: v for k, v in model.__dict__.items() if k not in exclude}