作为CRUD仔，经常这样的套路用ORM，想加个to_dict的方法来把ORM对象转换成json给前端返回，但已有的项目都是在各自的子类里写个to_dict的方法，太累了，放到基类可好？是可以的。
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from sqlalchemy import Column, String, create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class User(Base):
__tablename__ = 'user'
id = Column(String(20), primary_key=True)
name = Column(String(20))
def to_dict(self):
...
class School(Base):
__tablename__ = 'school'
id = ...
name = ...
def to_dict(self):
...
...
engine = create_engine('mysql+mysqlconnector://root:password@localhost:3306/test')
DBSession = sessionmaker(bind=engine)
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看declarative_base源码发现可以给塞个自定义的class进去作为基类，所以以上代码可以这样改进
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from sqlalchemy import inspect
from sqlalchemy.ext.declarative import declarative_base
class _Base:
__banned_cols__: List[str] = ['deleted_utc']
__extra_cols__: List[str] = []
def to_dict(self, **kwargs):
cols = self.__extra_cols__ + [c.name for c in inspect(self.__class__).c]
ret_dict = {col: getattr(self, col) for col in cols if hasattr(self, col) and col not in self.__banned_cols__}
for func in self.custom_funcs():
if callable(func):
ret_dict.update(func(ret_dict, **kwargs))
return ret_dict
def custom_funcs(self) -> List[FunctionType]:
return []
Base = declarative_base(cls=_Base)
...
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这样子类model class就没必要去再写一遍to_dict方法了
# NOTE: I am not responsible for any expired content.
created_date: 2020-12-11T22:39:38+08:00
update_date: 2021-02-12T22:14:58+08:00
comment_url: https://github.com/ferstar/blog/issues/31