我想使用orm在SQLAlchemy中复制模型实例(行)。我的想法是这样做的:
i = session.query(Model)
session.expunge(i)
old_id = i.id
i.id = None
session.add(i)
session.flush()
print i.id #New ID
可以试试这个:
>>> import array
>>> array
<module 'array' (built-in)>
>>> class A(array.array):
def __init__(self, *args):
super(array.array, self).__init__(*args)
print "init is fine for objects implemented in C"
>>> a=A('c')
init is fine for objects implemented in C
>>>
将看到相同的行为子类int、str等。
>>> import datetime
>>> class D(datetime.date):
def __new__(cls, year):
return datetime.date.__new__(cls, year, 1, 1)
>>> D(2008)
D(2008, 1, 1)