I have a many-to-many schema using an association object and the
association proxy. I'm able to add data via the ORM, but trying to
delete from the association (but not delete the left or right tables)
throws a "AssertionError: Dependency rule tried to blank-out primary
key column 'keyphrase_action.keyphrase_id' on instance
'<KeyphraseAction at 0x9da7d8c>'" error. My test code is below. Any
advice is appreciated!
import os, sys
from sqlalchemy import Column, Integer, String, Table, create_engine,
schema, types
from sqlalchemy import orm, MetaData, Column, ForeignKey
from sqlalchemy.orm import relation, mapper, sessionmaker
from sqlalchemy.ext.associationproxy import association_proxy
engine = create_engine('sqlite:////home/aw/desktop/test.db',
echo=True)
meta = MetaData(bind=engine)
# schema
keyphrase_table = schema.Table('keyphrase', meta.metadata,
schema.Column('id', types.Integer, primary_key = True,
autoincrement = True),
schema.Column('phrase', types.String(160), nullable = False),
)
action_table = schema.Table('action', meta.metadata,
schema.Column('id', types.Integer, primary_key = True,
autoincrement = True),
schema.Column('action_name', types.Text, nullable = False),
)
keyphrase_action_table = schema.Table('keyphrase_action',
meta.metadata,
schema.Column('keyphrase_id', types.Integer, schema.ForeignKey
('keyphrase.id'), primary_key = True),
schema.Column('action_id', types.Integer, schema.ForeignKey
('action.id'), primary_key = True),
schema.Column('is_deferred', types.Boolean, nullable = False),
)
meta.create_all()
# classes
class Keyphrase(object):
def __init__(self, phrase):
self.phrase = phrase
# creator function
def _getKeyphraseAction(d):
return KeyphraseAction(action = d['action'], isDeferred = d
['isDeferred'])
actions = association_proxy('keyphrase_action', 'action', creator
= _getKeyphraseAction)
class Action(object):
def __init__(self, name):
self.action_name = name
class KeyphraseAction(object):
def __init__(self, keyphrase = None, action = None, isDeferred =
False):
self.keyphrase = keyphrase
self.action = action
self.is_deferred = isDeferred
# mappers
mapper(Keyphrase, keyphrase_table)
mapper(Action, action_table)
mapper(KeyphraseAction, keyphrase_action_table, properties={
'keyphrase': relation(Keyphrase,
backref = 'keyphrase_action'),
'action': relation(Action),
})
# test code
Session = sessionmaker(bind=engine)
s = Session()
# add some data
kp = Keyphrase('fast')
a = Action('capture_email')
s.add(kp)
s.add(a)
s.commit()
# assciate the keyphrase to the action
kp.actions.append({'action':a,'isDeferred':True})
s.commit()
#remove the newly created association, leaving the keyphrase and
actions
kp = s.query(Keyphrase).get(kp.id)
for i, action in enumerate(kp.actions):
print action.action_name
kp.actions.remove(action) # this fails!
s.commit()
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