On Jan 20, 2006, at 5:36 PM, Michael Bayer wrote:
Also, if you want to gain some understanding of objectstore, which
would be helpful if you have any ideas to offer, i just committed a
nicer "dependency dump" function. If you turn on
sqlalchemy.mapping.objectstore.LOG = True , youll see a "task dump" in
your standard out that looks like this (if you run
examples/adjacencytree/byroot_tree.py) :
hi mike,
thanks for your detailed response.
i haven't digested everything yet,
but have encountered another problem.
the code which causes the problem is below.
the basic problem is that the objectstore
will try to execute two identical INSERTs
and hence get a PK unique error.
one thing to note here is that the
entered data doesn't actually have
any reference cycles - the
table definition provides only the
possibility of there being a self-ref.
in addition, in you set TEST_SELFREF
to False, the problem does not arise.
i've been putting in a bunch of
'print's in objectstore.py in order
to trace this.
in this case, the (possible) problem
seems to be that a PropHistory ends
up inside a UOWTransaction.saved_lists,
and hence the:
del self.uow.modified_lists[obj]
in UOWTransaction.post_exec() raises
a KeyError.
this causes the uow to not flush
the saved entries properly, causing
the next invocation of .commit()
to try a duplicate INSERT. (or at
least that's what i think is going
on).
i inspected via pdb and found that
self.uow.modified_lists contains a
vanilla 'C2' object only. basically
what i did was:
---
for obj in self.saved_lists:
print 'POST_EXEC saved_lists', obj
try:
obj.commit()
del self.uow.modified_lists[obj]
except KeyError:
print 'post_exec lists keyerror'
import pdb
pdb.set_trace()
pass
---
i then tried to infer how the PropHistory
got entered into the saved_lists by doing:
---
def register_saved_list(self, listobj):
if isinstance(listobj, attributes.PropHistory):
import pdb
pdb.set_trace()
self.saved_lists.append(listobj)
---
but i don't really grok whether listobj
is supposed to be a list of objs so i
wasn't sure what to fix (or whether i'm
honing in on the actual problem).
i did notice that the PropHistory in
this case has a .obj attribute that in
fact seems to be the 'C2' object instance
that should be deleted from modified_lists,
but hesitated because of my lack of
understanding.
as always, if you have any thoughts
they'd be greatly appreciated.
thanks, d
(the actual code that breaks follows)
---
import sqlalchemy as rdb
TEST_SELFREF = True
rdb.mapping.objectstore.LOG = True
# Setup data
engine = rdb.create_engine('sqlite://', echo=True)
t1 = rdb.Table(
't1', engine,
rdb.Column('id', rdb.Integer, primary_key=True),
rdb.Column('selfref_id', rdb.Integer, rdb.ForeignKey('t1.id')),
)
t1.create()
class C1(object):
pass
m1 = rdb.mapper(C1, t1)
if TEST_SELFREF:
m1.add_property(
'selfref',
rdb.relation(C1, primaryjoin=(t1.c.id==t1.c.selfref_id),
foreignkey=t1.c.id))
t2 = rdb.Table(
't2', engine,
rdb.Column('id', rdb.Integer, primary_key=True),
rdb.Column('t1id', rdb.Integer, rdb.ForeignKey(t1.c.id)),
)
t2.create()
class C2(object):
pass
m2 = rdb.mapper(C2, t2)
m2.add_property(
't1', rdb.relation(m1, backref='t2s')
)
# Test
import itertools
idgen = itertools.count()
for i in xrange(10):
a1 = C1()
a1.id = idgen.next()
rdb.objectstore.commit()
for a1 in m1.select():
a2 = C2()
a2.id = idgen.next()
a2.t1 = a1
rdb.objectstore.commit()
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