我最近尝试将代码从Python 2.7升级到Python 3.4。
在Python 2.7中,这很简单:
class Maatje(CommonColumns):
koppelvoorstellen = db.relationship("Koppelvoorstel",
primaryjoin="or_(Maatje.id == Koppelvoorstel.deelnemerID," \
+ "Maatje.id == Koppelvoorstel.vrijwilligerID)",
cascade="all,delete-orphan")
但是,使用Python 3.4(以及针对Python 3.4从源代码编译的mod_wsgi 4.4)在我的Apache 2.4错误日志中尝试查询Maatje时出现错误:
[wsgi:error] [pid 6169] sqlalchemy.exc.ProgrammingError:
(mysql.connector.errors.ProgrammingError) 1064 (42000): You have an
error in your SQL syntax; check the manual that corresponds to your
MySQL server version for the right syntax to use near '%(param_1)s =
koppelvoorstel.`vrijwilligerID`' at line 3 [SQL: 'SELECT
koppelvoorstel.id AS koppelvoorstel_id, koppelvoorstel.aangemaakt AS
koppelvoorstel_aangemaakt, koppelvoorstel.gewijzigd AS
koppelvoorstel_gewijzigd, koppelvoorstel.etag AS koppelvoorstel_etag,
koppelvoorstel.`deelnemerID` AS `koppelvoorstel_deelnemerID`,
koppelvoorstel.`vrijwilligerID` AS `koppelvoorstel_vrijwilligerID`,
koppelvoorstel.akkoordvrijwilliger AS
koppelvoorstel_akkoordvrijwilliger, koppelvoorstel.akkoorddeelnemer AS
koppelvoorstel_akkoorddeelnemer,
koppelvoorstel.redenafwijzingvrijwilliger AS
koppelvoorstel_redenafwijzingvrijwilliger,
koppelvoorstel.redenafwijzingdeelnemer AS
koppelvoorstel_redenafwijzingdeelnemer, koppelvoorstel.stopdatum AS
koppelvoorstel_stopdatum, koppelvoorstel.redenstoppenvrijwilliger AS
koppelvoorstel_redenstoppenvrijwilliger,
koppelvoorstel.redenstoppendeelnemer AS
koppelvoorstel_redenstoppendeelnemer \\nFROM koppelvoorstel \\nWHERE %
(param_1)s = koppelvoorstel.`deelnemerID` OR %(param_1)s =
koppelvoorstel.`vrijwilligerID`'] [parameters: {'param_1': 1}]
对我来说似乎是完全有效的SQL(不过我假设\\ n会成为换行符)。我尝试使用phpMyAdmin(不带\ n)并使用参数(一个)填充SQL查询,它可以理解查询并得出有效的结果。
我尝试用其他形式写
primaryjoin
,例如不带字符串,带有or_和带有“ |”作为或运算符。还尝试了in_
运算符。我正在使用带有mod_wsgi 4.4,SQLalchemy 1.0.12和Flask-SQLalchemy 2.1的Ubuntu 14.04。
我正在使用
python3-mysql.connector
(适用于MySQL Connector / Python的Ubuntu软件包)。如果删除一个相等比较之一(与哪一个无关)并且不使用
or_
运算符,则不会引发错误。但是我都需要使用or_
运算符。2016年3月6日:
现在,我将问题隔离了一点。使用python2.7运行以下代码没有问题:
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_ECHO'] = True
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+mysqlconnector://username:password@127.0.0.1/primaryjoindb'
db = SQLAlchemy(app)
class Coupleproposal(db.Model):
__tablename__ = 'coupleproposal'
id = db.Column(db.Integer, primary_key=True)
participantID = db.Column(db.Integer, db.ForeignKey('buddy.id'), nullable = False)
volunteerID = db.Column(db.Integer, db.ForeignKey('buddy.id'), nullable = False)
participant = db.relationship("Buddy", foreign_keys=[participantID])
volunteer = db.relationship("Buddy", foreign_keys=[volunteerID])
__table_args__ = (db.UniqueConstraint('participantID', 'volunteerID', name='_couple_uc'),)
class Buddy(db.Model):
__tablename__ = 'buddy'
id = db.Column(db.Integer, primary_key=True)
coupleproposals = db.relationship("Coupleproposal", \
primaryjoin="(Buddy.id == Coupleproposal.participantID) | (Buddy.id == Coupleproposal.volunteerID)", \
cascade="all,delete-orphan")
db.create_all()
b1 = Buddy()
b2 = Buddy()
db.session.add(b1)
db.session.add(b2)
cp1 = Coupleproposal(participantID=1, volunteerID=1)
db.session.add(cp1)
db.session.commit()
for aBuddy in db.session.query(Buddy).all():
print(aBuddy.id)
print(aBuddy.coupleproposals)
但是使用python3.4运行代码会引发以下错误:
sqlalchemy.exc.ProgrammingError:(mysql.connector.errors.ProgrammingError)1064(42000):您的SQL语法有错误;请查看与您的MySQL服务器版本相对应的手册以获取正确的语法,以在第3行[SQL:'SELECT coupleproposal.id AS coupleproposal_id,coupleproposal。
volunteerID
AS participantID
,coupleproposal。coupleproposal_participantID
AS volunteerID
\ nFROM coupleproposal \ nWHERE%(param_1)s = coupleproposal。coupleproposal_volunteerID
OR%(param_1)s = coupleproposal。participantID
'] [参数:{'param_1' :1}] 最佳答案
如果我使用其他连接器(例如pymysql),则可以使用。在这里回答(不是我本人,而是SQLalchemy的仓库所有者):https://bitbucket.org/zzzeek/sqlalchemy/issues/3669/primaryjoin-attribute-with-or_-operator
关于python - SQLalchemy primaryjoin属性在Python 3.4中不起作用(使用Python 2.7工作),我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/35814911/