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(以及根据 Python 3.4 从源代码编译的 mod_wsgi 4.4),当我尝试查询 Maatje 时,我在 Apache 2.4 错误日志中收到错误:
[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}]
对我来说看起来是完全有效的 SQL(不过我假设\\n 将成为换行符)。我尝试使用 phpMyAdmin(不带\n)并填写参数(一个)进行 SQL 查询,它理解该查询并得出有效的结果。
我尝试过以其他形式编写 primaryjoin
,例如不带字符串、使用 or_ 和使用“|”作为或运算符。还尝试了 in_
- 运算符。
我使用 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
(MySQL Connector/Python 的 Ubuntu 软件包)。
如果我删除其中一个相等比较(无论是哪一个)并且不使用 or_
运算符,那么它不会引发错误。但我需要同时使用 or_
运算符。
2016 年 3 月 6 日: 现在我已经稍微隔离了这个问题。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 运行代码会抛出此错误:
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 = coupleproposal.
volunteerID
' at line 3 [SQL: 'SELECT coupleproposal.id AS coupleproposal_id, coupleproposal.participantID
AScoupleproposal_participantID
, coupleproposal.volunteerID
AScoupleproposal_volunteerID
\nFROM coupleproposal \nWHERE %(param_1)s = coupleproposal.participantID
OR %(param_1)s = coupleproposal.volunteerID
'] [parameters: {'param_1': 1}]
最佳答案
如果我使用不同的连接器(例如 pymysql),它就可以工作。在这里回答(不是我,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 起作用),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35814911/