python - SQLAlchemy > 类型错误 : 'instancemethod' object does not support item assignment

Question

这是我得到的:

from sqlalchemy import *
from sqlalchemy.orm import *
from web.models.card import *
connectionString = "postgresql://www:www@localhost/prod"
databaseEngine = create_engine(connectionString)
sessionFactory = sessionmaker(autoflush = True, autocommit = False, bind = databaseEngine)
session = sessionFactory()
CardsCollection = session.query(card).all()
_content = {}
for index in range(0, len(CardsCollection)):
    c = CardsCollection[index]
    _content[index] = c
print json.dumps(_content)

这里是错误:

Traceback (most recent call last):
  File "/home/src/py/raspberry/src/dictionaryTest.py", line 15, in 
    CardsCollection = session.query(card).all()
  File "/usr/local/lib/python2.6/dist-packages/sqlalchemy/orm/query.py", line 1453, in all
    return list(self)
  File "/usr/local/lib/python2.6/dist-packages/sqlalchemy/orm/query.py", line 1676, in instances
    rows = [process[0](row, None) for row in fetch]
  File "/usr/local/lib/python2.6/dist-packages/sqlalchemy/orm/mapper.py", line 2234, in _instance
    populate_state(state, dict_, row, isnew, only_load_props)
  File "/usr/local/lib/python2.6/dist-packages/sqlalchemy/orm/mapper.py", line 2113, in populate_state
    populator(state, dict_, row)
  File "/usr/local/lib/python2.6/dist-packages/sqlalchemy/orm/strategies.py", line 127, in new_execute
    dict_[key] = row[col]
TypeError: 'instancemethod' object does not support item assignment

有人可以帮我解决这个问题吗？我已经尝试了一些东西，并研究了字典是如何工作的……但它并没有让我大吃一惊。

[编辑奇怪的分辨率] 显然，覆盖卡片模型上的 self.__dict__(self) 方法就是这样做的。不过，我不完全确定为什么。

Answer 1

__dict__ 是 special attribute保持实例的当前状态，用方法覆盖它肯定会导致麻烦。