Python SQLAlchemy声明性。指定要选择的列
声明性基:Python SQLAlchemy声明性。指定要选择的列,python,sqlalchemy,Python,Sqlalchemy,声明性基: Base = declarative_base() Base.query = Session.query_property() 班级: class Cheat(Base): __tablename__ = 'cheats' id = Column(Integer, primary_key = True, autoincrement = True) cheat = Column(Text) name = Column(String(255), index = Tr
Base = declarative_base()
Base.query = Session.query_property()
班级:
class Cheat(Base):
__tablename__ = 'cheats'
id = Column(Integer, primary_key = True, autoincrement = True)
cheat = Column(Text)
name = Column(String(255), index = True)
_html = Column('html', Text)
_slug = Column('slug', String(255))
@hybrid_property
def html(self):
return self._html
@html.setter
def set_html(self, md):
from markdown import markdown
self._html = markdown(md)
@hybrid_property
def slug(self):
return self._slug
@slug.setter
def set_slug(self, name):
self._slug = slugify(name)
def __init__(self, name, cheat):
self.name = name
self.slug = name
self.cheat = cheat
self.html = cheat
def __repr__(self):
return "Cheat<%s>" % self.name
SQLAlchemy将生成类似以下内容的SQL语句:
从作弊中选择名称、slug、作弊、html
但我希望我的SQL语句是:
选择名称,从作弊中选择slug
所以我需要指定要检索哪些列,因为我实际上不需要通过网络从数据库中提取大量文本。
我如何做到这一点?将它们定义为,那么只有在访问
from sqlalchemy.orm import deferred
class Cheat(Base):
__tablename__ = 'cheats'
id = Column(Integer, primary_key = True, autoincrement = True)
cheat = deferred(Column(Text))
name = Column(String(255), index = True)
_html = Column('html', Text)
_slug = deferred(Column('slug', String(255)))
from sqlalchemy.orm import deferred
class Cheat(Base):
__tablename__ = 'cheats'
id = Column(Integer, primary_key = True, autoincrement = True)
cheat = deferred(Column(Text))
name = Column(String(255), index = True)
_html = Column('html', Text)
_slug = deferred(Column('slug', String(255)))
for name, slug in session.query(Cheat.name, Cheat.slug):
print name, slug