我在课堂上使用SELECT *
FROM PlacementDetail_Temp PDT LEFT JOIN
dbo.[Authorization] AUTH
on AUTH.PlacementDetailID = PDT.PlacementDetailID and
AUTH.PayorID = @PayorID LEFT JOIN
dbo.Provider SP_as_PR
on SP_as_PR.ProviderID in
(Select PR.ProviderID
from dbo.Provider PR JOIN
dbo.ProviderSponsor PS
ON PR.ProviderID = PS.ProviderID and
PS.SponsorID = AUTH.SponsorID
where IsSponsor = 'True'
)
实现了只写属性。奇怪的是，@property在具有此属性的类和相应实例上的行为不同。
hasattrfrom werkzeug.security import generate_password_hash, check_password_hash
from flask_login import UserMixin
class User(Base, UserMixin):
# codes omitted...
@property
def password(self):
raise AttributeError("password is a write-only attribute!")
@password.setter
def password(self, password):
self.password_hash = generate_password_hash(password)
def verify_password(self, password):
return check_password_hash(self.password_hash, password)
根据In [6]: hasattr(User,'password')
Out[6]: True
In [7]: u1=User()
In [9]: hasattr(u1,'password')
Out[9]: False
In [12]: getattr(User,'password')
Out[12]: <property at 0x1118a84a8>
In [13]: getattr(u1,'password')
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-13-b1bb8901adc7> in <module>
----> 1 getattr(u1,'password')
~/workspace/python/flask_web_development/fisher/app/models.py in password(self)
82 @property
83 def password(self):
---> 84 raise AttributeError("password is a write-only attribute!")
85
86 @password.setter
AttributeError: password is a write-only attribute!
的结果，getattr尝试执行该方法并引发错误，而getattr(u1, 'password')不执行getattr(User, 'password')方法。他们为什么表现不同？