On 5/6/15 9:56 AM, st...@canary.md wrote:
Hmm, I don't think I could listen to the attribute event; it's saying
that the AssociationProxy doesn't have "dispatch".
oh. well yes, the event has to be on the "mapped" attributes that the
association proxy is proxying. the associationproxy is just a Python
trick to make two object hops look like one.
Also, suppose I could detect the orphan-deletes earlier, what's the
best way to suppress the objects marked as dirty?
Here's my version of your code if it helps:
https://github.com/canaryhealth/sqlalchemy_audit/blob/master/sqlalchemy_audit/history_meta.py
Your help is much appreciated! Thanks very much.
On Wednesday, April 29, 2015 at 1:00:14 PM UTC-4, Michael Bayer wrote:
On 4/29/15 12:11 PM, st...@canary.md <javascript:> wrote:
Since my association object doesn't have extra columns, the row
('bob, 'apple') will be deleted. However, if there are extra
columns, then having it marked as "dirty" is desired.
Perhaps I would delay my recording of my audit rows until after
orphans are resolved. I am already using "after_flush", is there
another event I could use? Otherwise, I would need to detect an
object as an association object without extra columns and perform
specific logic to handle this. Is there a way to identify
association objects?
there's not an event in between the time that the orphan thing is
calculated and the SQL is emitted. After flush is a candidate if
you can make that work.
The approach using the event is just to make an event listener for
this purpose and apply it to those classes that need it:
class MyParent(Base):
# ...
associations = relationship("MyAssociation", cascade="all,
delete-orphan")
@event.listens_for(MyParent.associations, "remove")
def on_remove(obj, child, initiator):
object_session(obj).delete(child)
class MyAssociation(Base):
# ...
Thanks!
On Tuesday, April 28, 2015 at 7:53:21 PM UTC-4, Michael Bayer wrote:
On 4/28/15 6:57 PM, st...@canary.md wrote:
Hi,
Background information: I am trying to implement
functionality similar to the history_meta.py example
(http://docs.sqlalchemy.org/en/rel_0_9/_modules/examples/versioned_history/history_meta.html).
I am listening for after_flush events and create an audit
record and am having problems with association objects. Here
is an example:
class User(Auditable, self.Base, ComparableEntity):
__tablename__ = 'usertable'
id = Column(Integer, primary_key=True)
name = Column(String)
keywords = association_proxy('assocs', 'keyword')
class Keyword(Auditable, self.Base, ComparableEntity):
__tablename__ = 'keywordtable'
id = Column(Integer, primary_key=True)
word = Column(String)
class UserKeyword(Auditable, self.Base, ComparableEntity):
__tablename__ = 'userkeywordtable'
user_id = Column(Integer, ForeignKey("usertable.id
<http://usertable.id>"),
primary_key=True)
keyword_id = Column(Integer,
ForeignKey("keywordtable.id <http://keywordtable.id>"),
primary_key=True)
user = relationship(User,
backref=backref("assocs",
cascade="all, delete-orphan"))
keyword = relationship(Keyword)
def __init__(self, keyword=None, user=None):
self.user = user
self.keyword = keyword
apple = Keyword(word='apple')
pear = Keyword(word='pear')
bob = User(name='bob')
bob.keywords = [apple, pear]
sess.add(bob)
sess.commit()
bob.keywords.remove(apple) <====== this is when my
question is about
sess.commit()
When we remove the keyword, it marks the UserKeyword
association object is "dirty" instead of "deleted". Why is
that? Since the row is being removed, I would expect it to
be marked as "deleted", so that I could make an audit record
indicating it was deleted.
does the row actually get deleted? the calculation of
"orphan" isn't done until flush time, because theoretically
you could be associating the UserKeyword to another User.
it doesn't look like the versioned rows recipe has support
for this use case right now. You could force the up-front
delete using a "remove" attribute event on that collection.
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