OK, my last post I tried to edit the code while I was posting to simplify
it, and clearly missed a bit. Here's the case that is failing simplified as
much as possible. I get a key error on the last line. I don't have sqlite
installed, so I skipped actually creating the engine, but I'm not sure that
matters. Feel free to correct me if I'm wrong.
from sqlalchemy import Column, String, Integer, ForeignKey
from sqlalchemy.orm import relationship, backref
from sqlalchemy.ext.associationproxy import association_proxy
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class Person(Base):
__tablename__ = 'Person'
id = Column(Integer, primary_key=True)
first_name = Column(String(80))
last_name = Column(String(120))
events = association_proxy('person_events','Event')
class PersonEvent(Base):
__tablename__ = 'PersonEvent';
person_id = Column(Integer, ForeignKey('Person.id'), primary_key=True)
event_id = Column(Integer, ForeignKey('Event.id'), primary_key = True)
role = Column(String(40))
# bi-directional attribute / collection of "Person" / "Event"
person = relationship(Person,
backref=backref('person_events',
cascade="all, delete-orphan"))
# reference to the Event object
event = relationship('Event')
def __init__(self, person=None, event=None, role=None):
self.person = person
self.event = event
self.role = role
class Event(Base):
__tablename__ = 'Event'
id = Column(Integer, primary_key=True)
short_name = Column(String(40))
p1 = Person(first_name='Eric', last_name='Wittle')
p1.events.append(Event(short_name='Birth'))
I thought I was fairly faithfully following the example in Simplifying
Association Proxies. I'm assuming the first argument to assocation_proxy is
the name of the backref created in the relationship in the association
object, but I'm unclear on that. I tried your code suggestion (minus
actually creating the engine and adding in the __init__ method to the
association object to work around __init__ takes 1 positional argument but
two were given error). The edited version I ran is below, and it also gives
KeyError:
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
import datetime
from sqlalchemy.ext.associationproxy import association_proxy
Base = declarative_base()
class Person(Base):
__tablename__ = 'Person'
__table_args__ = {'mysql_charset':'utf8'}
id = Column(Integer, primary_key=True)
full_name = Column(String(240))
email = Column(String(120),unique=True)
other_data = Column(String(50))
events = association_proxy('PersonEvent','Event')
class PersonEvent(Base):
__tablename__ = 'PersonEvent'
__tableargs__ = {'mysql_charset':'utf8'}
person_id = Column(Integer, ForeignKey('Person.id'), primary_key=True)
event_id = Column(Integer, ForeignKey('Event.id'), primary_key = True)
role = Column(String(40))
# bi-directional attribute / collection of "Person" / "Event"
person = relationship('Person',
backref=backref("PersonEvent",
cascade="all, delete-orphan"))
# reference to the Event object
event = relationship('Event')
def __init__(self, person=None, event=None, role=None):
self.person = person
self.event = event
self.role = role
class Event(Base):
__tablename__ = 'Event'
__table_args__ = {'mysql_charset':'utf8'}
id = Column(Integer, primary_key=True)
short_name = Column(String(40))
name = Column(String(240))
other_data = Column(String(100))
p1 = Person(id=1, full_name='Eric L. Wittle', email='er...@wittle.net')
e1 = Event(id=1, name='Birth')
p1.events.append(e1)
This is running python 3.5.1 with SQLAlchemy 1.1.0b2.
-Eric
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