无法捕获SQLAlchemy IntegrityError
无法捕获SQLAlchemy IntegrityError
提问于 2014-07-02 11:12:58
尽管我可能会尝试，但我似乎不能正确地捕获sqlalchemy IntegrityError：
from sqlalchemy import exc
try:
insert_record()
except exc.IntegrityError, exc:
print exc # this is never called
handle_elegantly() # this is never called正如人们可能预期的那样：
IntegrityError: (IntegrityError) insert or update on table "my_table"
violates foreign key constraint "my_table_some_column_fkey"我试着明确地说：
from sqlalchemy.exc import IntegrityError更新：
我发现了一些似乎与这里发生的情况相吻合的东西，即在会话刷新到数据库之前以及在执行try/except块之后才抛出完整性错误：Trying to catch integrity error with SQLAlchemy
但是，在try块中添加session.flush()会生成InvalidRequestError
ERROR:root:This Session's transaction has been rolled back due to a previous
exception during flush. To begin a new transaction with this Session,
first issue Session.rollback().
Original exception was: (IntegrityError)回答 4
Stack Overflow用户
发布于 2016-07-05 10:21:38
我在我的Flask应用程序中也有同样的需求，我像下面这样处理它，它可以工作：
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy import exc
db = SQLAlchemy(Flask(__name__))
try:
db.session.add(resource)
return db.session.commit()
except exc.IntegrityError:
db.session.rollback()Stack Overflow用户
发布于 2014-09-17 04:33:58
一旦IntegrityError被引发，无论您是否捕获到错误，您正在工作的会话都将失效。当第二条错误消息指示您To begin a new transaction with this Session, first issue Session.rollback().继续使用会话时，您需要发出一个session.rollback()
我不能确定，但我猜您或您的web框架正在尝试继续使用以某种方式引发IntegrityError的会话。我建议您在捕获异常后或在handle_elegantly函数中发出session.rollback()。
如果你运行下面的代码，你就会明白我的意思：
from sqlalchemy import types
from sqlalchemy import exc
from sqlalchemy import create_engine
from sqlalchemy.schema import Column
from zope.sqlalchemy import ZopeTransactionExtension
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, scoped_session
Base = declarative_base()
class User(Base):
__tablename__ = 'user'
name = Column(types.String, primary_key=True)
def handle_elegantly(name):
session = DBSession()
session.add(User(name=name))
session.flush()
print 'Exception elegantly handled!!\n'
def pretend_view(request):
"""Pretend view in a Pyramid application using pyramid_tm"""
session = DBSession()
user = User()
print '\n-------Here we rollback before continuing -------'
try:
session.add(user)
session.flush()
except exc.IntegrityError:
session.rollback()
handle_elegantly('This will run fine')
print '\n------- Here we do not, and this will error -------'
try:
session.add(user)
session.flush()
except exc.IntegrityError:
handle_elegantly('Exception will be raised')
if __name__ == '__main__':
engine = create_engine('sqlite://')
global DBSession
DBSession = scoped_session(
sessionmaker(extension=ZopeTransactionExtension()))
DBSession.configure(bind=engine)
Base.metadata.bind = engine
Base.metadata.create_all()
pretend_view("dummy request")Stack Overflow用户
发布于 2021-05-17 17:09:44
捕获错误后，必须添加session.rollback()：
try:
session.flush()
except IntegrityError:
session.rollback()页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/24522290
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