python orm

model.py

class Model(object):
    id: int = None

    def __init__(self, **kwargs):
        annotations = {**self.__annotations__, **Model.__annotations__}
        for name, annotated in annotations.items():
            if name in kwargs:
                value = kwargs.get(name)
                value = annotated(value)
                setattr(self, name, value)


class User(Model):
    username: str

if __name__ == '__main__':
    print(User.__dict__, User.__annotations__)
    f1 = User(username='username1')
    print(f1.__dict__, f1.__annotations__, id(f1.username))
    f2 = User(username='username2')
    print(f2.__dict__, id(f2.username))

在 init 阶段可以拿到所有的字段定义和类型和默认值。想怎么改都行了。