Python 如何验证是否配置了sqlalchemy会话?
sqlalchemy会话的标准/正常配置:Python 如何验证是否配置了sqlalchemy会话?,python,sqlalchemy,Python,Sqlalchemy,sqlalchemy会话的标准/正常配置: from sqlalchemy.orm import scoped_session, sessionmaker DBSession = scoped_session(sessionmaker(extension=ZopeTransactionExtension())) # 0 engine = engine_from_config(config, 'sqlalchemy.') try: DBSession.query('1').scalar
from sqlalchemy.orm import scoped_session, sessionmaker
DBSession = scoped_session(sessionmaker(extension=ZopeTransactionExtension())) # 0
engine = engine_from_config(config, 'sqlalchemy.')
try:
DBSession.query('1').scalar() # 1
except UnboundExecutionError:
pass # expected here - session is not bound
DBSession.configure(bind=engine) # 2
try:
DBSession.query('1').scalar() # 3
except UnboundExecutionError:
pass # not expected here - session is bound ?
任何使用未绑定会话的尝试都将以断开?
会话对象结束-要使用会话,我必须创建一个第0行的新会话
如何检查会话对象是否未绑定并始终只保留一个对象?您应该保留对会话工厂的引用 而不是
DBSession = scoped_session(sessionmaker(extension=ZopeTransactionExtension())) # 0
engine = engine_from_config(config, 'sqlalchemy.')
你可以
engine = engine_from_config(config, 'sqlalchemy.')
Session= sessionmaker(extension=ZopeTransactionExtension(), bind=engine)
DBSession= Session()
每次需要会话时,只需调用session()
。没有必要有一个单身汉