SQLalchemy primaryjoin属性在Python 3.4中不起作用（使用Python 2.7工作）

我最近尝试将我们的代码从Python 2.7升级到Python 3.4 .

在Python 2.7中，这简单有效：

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（以及从Python 3.4源代码编译的mod_wsgi 4.4）我在Apache 2.4错误日志中尝试查询Maatje时收到错误：

[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}]

看起来对我来说是完全有效的SQL（我假设\ n将成为换行符） . 我尝试使用phpMyAdmin（没有\ n's）和参数填充（一个）的SQL查询，它理解了查询并得出了有效的结果 .

我尝试用其他形式编写 primaryjoin ，例如没有字符串，用or_和"|"作为or-operator . 还尝试了 in_ -operator .

我正在使用Ubuntu 14.04和mod_wsgi 4.4，SQLalchemy 1.0.12和Flask-SQLalchemy 2.1 .

我正在使用 python3-mysql.connector （用于MySQL Connector / Python的Ubuntu包） .

如果我删除其中一个相等比较（无关紧要）并且不使用 or_ -operator那么它不会抛出错误 . 但我需要使用 or_ -operator .

6 March 2016: 现在我已经把问题搞砸了 . 使用python2.7运行以下代码不会产生任何问题：

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运行代码会抛出此错误：

sqlalchemy.exc.ProgrammingError：（mysql.connector.errors.ProgrammingError）1064（42000）：您的SQL语法有错误;查看与MySQL服务器版本对应的手册，以便在第3行的'％（param_1）s = coupleproposal.volunteerID'附近使用正确的语法[SQL：'SELECT coupleproposal.id AS coupleproposal_id，coupleproposal.participantID AS coupleproposal_participantID，coupleproposal . volunteerID AS coupleproposal_volunteerID \ nFROM coupleproposal \ nWHERE％（param_1）s = coupleproposal.participantID OR％（param_1）s = coupleproposal.volunteerID'] [parameters：{'param_1'：1}]