通过SqlAlchemy模型类定义中的@property进行Python获取和设置：HOWTO

Question

因此，我对sqlalchemy和ORM非常陌生。我有一个现有的数据库postgresql，并且已经创建了一个与数据库进行通信的模型。下面是我的Transcribers表的类。通过它进行查询时，所有这些都可以工作。我在设置类中的获取器和设置器时遇到问题。

class Transcriber(Base):
    __tablename__ = 'transcribers'
    __table_args__ = (
    UniqueConstraint('projectid', 'email'),
    )

    transcriberid = Column(Integer, primary_key=True, server_default=text("nextval('transcribers_transcriberid_seq'::regclass)"))
    projectid = Column(ForeignKey(u'projects.projectid', ondelete=u'CASCADE'), index=True)
    email = Column(Text, nullable=False)
    created = Column(DateTime, nullable=False, server_default=text("now()"))
    onwebsite = Column(Boolean, nullable=False, server_default=text("true"))

    def __repr__(self):
        return "<Transcriber(transcriberid:'%s', projectID:'%s', email:'%s', created:'%s', onwebsite:'%s'" \
        %(self.transcriberid, self.projectid, self.email, self.created,   self.onwebsite)

    @property
    def transcriberid(self):
        return self.transcriberid

    def email(self):
        return self.email

    @email.setter
    def email(self, value):
        self.email = value

    project = relationship(u'Project')

我不确定如何使用@property方法访问对象内的不同变量。我想使用这种方法，因为我相信它更具Python感。

因此，现在我该如何实际调用这些方法了。并且它们设置正确。

我开始上课时收到此错误

Traceback (most recent call last):
File "./test.py", line 4, in <module>
   from peraAPI import DBSession, getProjectbyId, getTransById
     File "/Users/tcrha/bin/working/PeraPera/peraAPI/__init__.py", line 7, in <module>
from model_local import Project, Transcriber
  File "/Users/tcrha/bin/working/PeraPera/peraAPI/model_local.py", line 110, in <module>
class Transcriber(Base):
  File "/Users/tcrha/bin/working/PeraPera/peraAPI/model_local.py", line 133, in      Transcriber
@email.setter
AttributeError: 'function' object has no attribute 'setter'

Answer 1

您可以使用hybrid_property。在这种情况下，代码的简化版本应如下所示：

from sqlalchemy.ext.hybrid import hybrid_property

class Transcriber(Base):
    __tablename__ = 'transcribers'
    __table_args__ = (
    UniqueConstraint('projectid', 'email'),
    )

    transcriberid = Column(Integer, primary_key=True, server_default=text("nextval('transcribers_transcriberid_seq'::regclass)"))
    projectid = Column(ForeignKey(u'projects.projectid', ondelete=u'CASCADE'), index=True)
    created = Column(DateTime, nullable=False, server_default=text("now()"))
    onwebsite = Column(Boolean, nullable=False, server_default=text("true"))

    _email = Column('email', Text, nullable=False)

    @hybrid_property
    def email(self):
        return self._email

    @email.setter
    def email(self, email):
        self._email = email