clock.py 文件源码

def build_history_class(
        cls: declarative.DeclarativeMeta,
        prop: T_PROPS,
        schema: str = None) -> nine.Type[TemporalProperty]:
    """build a sqlalchemy model for given prop"""
    class_name = "%s%s_%s" % (cls.__name__, 'History', prop.key)
    table = build_history_table(cls, prop, schema)
    base_classes = (
        TemporalProperty,
        declarative.declarative_base(metadata=table.metadata),
    )
    class_attrs = {
        '__table__': table,
        'entity': orm.relationship(
            lambda: cls,
            backref=orm.backref('%s_history' % prop.key, lazy='dynamic')
        ),
    }

    if isinstance(prop, orm.RelationshipProperty):
        class_attrs[prop.key] = orm.relationship(
            prop.argument,
            lazy='noload')

    model = type(class_name, base_classes, class_attrs)
    return model