本文整理汇总了Python中z3c.saconfig.Session.rollback方法的典型用法代码示例。如果您正苦于以下问题：Python Session.rollback方法的具体用法？Python Session.rollback怎么用？Python Session.rollback使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类z3c.saconfig.Session的用法示例。
在下文中一共展示了Session.rollback方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Python代码示例。
示例1: add_column_to_account
# 需要导入模块: from z3c.saconfig import Session [as 别名]
# 或者: from z3c.saconfig.Session import rollback [as 别名]
def add_column_to_account(context):
""" Adds a new column to the Account table which indicates whether the
account in question is a guest account, a converted guest account or
neither.
"""
session = Session()
if ColumnExists(session, "account", "account_type"):
log.info("account_type column already exists in Account table!")
return
log.info('Adding account_type column to Account table')
q = "ALTER TABLE account ADD COLUMN account_type CHARACTER varying(16)";
try:
session.execute(q)
except InternalError, e:
# There might be previous SQL queries which failed due to the
# account_type column not yet being in the Account table. For example,
# the authenticate method in authentication.py does such a query.
session.rollback()
transaction.commit()
session.execute(q)