On 4/14/15 6:38 AM, Steven Winfield wrote:
Hi,
I think I've found a bug triggered by bulk deletes that use the
(default) "evaluate" strategy.
a bug is created at
https://bitbucket.org/zzzeek/sqlalchemy/issue/3365/evaluator-cant-locate-orm-entity-when
and for now you need to compare using the columns, not the relationship,
e.g. Child._id_parent == parent.id, if you want to use evaluate there.
For example:
from sqlalchemy import Column, Integer, Text, ForeignKey, create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship
Base = declarative_base()
class Parent(Base):
__tablename__ = "parent"
id = Column(Integer, primary_key=True)
class Child(Base):
__tablename__ = "child"
_id_parent = Column("id_parent", Integer, ForeignKey(Parent.id),
primary_key=True)
name = Column(Text, primary_key=True)
parent = relationship(Parent)
engine = create_engine('sqlite://')
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
session = Session()
session.bind.echo = True
# Make a parent
p = Parent(id=1)
session.add(p)
session.commit()
# Add a child
c = Child(name="foo", parent=p)
session.add(c)
session.commit()
# c is still in the session
session.query(Child).filter(Child.parent == p).delete("evaluate")
...give the following traceback:
File user!winfis!test_bed.py, line 34, in :
session.query(Child).filter(Child.parent == p).delete("evaluate")
<file:%5Cuser%21winfis%21test_bed.py:34:exception>
File
R:\sw\external\20150407-0\python27\lib\site-packages\sqlalchemy-0.9.7-py2.7-win32.egg\sqlalchemy\orm\query.py,
line 2670, in delete : delete_op.exec_()
<file:%5CR:%5Csw%5Cexternal%5C20150407-0%5Cpython27%5Clib%5Csite-packages%5Csqlalchemy-0.9.7-py2.7-win32.egg%5Csqlalchemy%5Corm%5Cquery.py:2670:exception>
File
R:\sw\external\20150407-0\python27\lib\site-packages\sqlalchemy-0.9.7-py2.7-win32.egg\sqlalchemy\orm\persistence.py,
line 896, in exec_ : self._do_pre_synchronize()
<file:%5CR:%5Csw%5Cexternal%5C20150407-0%5Cpython27%5Clib%5Csite-packages%5Csqlalchemy-0.9.7-py2.7-win32.egg%5Csqlalchemy%5Corm%5Cpersistence.py:896:exception>
File
R:\sw\external\20150407-0\python27\lib\site-packages\sqlalchemy-0.9.7-py2.7-win32.egg\sqlalchemy\orm\persistence.py,
line 958, in _do_pre_synchronize : eval_condition(obj)]
<file:%5CR:%5Csw%5Cexternal%5C20150407-0%5Cpython27%5Clib%5Csite-packages%5Csqlalchemy-0.9.7-py2.7-win32.egg%5Csqlalchemy%5Corm%5Cpersistence.py:958:exception>
File
R:\sw\external\20150407-0\python27\lib\site-packages\sqlalchemy-0.9.7-py2.7-win32.egg\sqlalchemy\orm\evaluator.py,
line 116, in evaluate : right_val = eval_right(obj)
<file:%5CR:%5Csw%5Cexternal%5C20150407-0%5Cpython27%5Clib%5Csite-packages%5Csqlalchemy-0.9.7-py2.7-win32.egg%5Csqlalchemy%5Corm%5Cevaluator.py:116:exception>
File
R:\sw\external\20150407-0\python27\lib\site-packages\sqlalchemy-0.9.7-py2.7-win32.egg\sqlalchemy\orm\evaluator.py,
line 72, in : return lambda obj: get_corresponding_attr(obj)
<file:%5CR:%5Csw%5Cexternal%5C20150407-0%5Cpython27%5Clib%5Csite-packages%5Csqlalchemy-0.9.7-py2.7-win32.egg%5Csqlalchemy%5Corm%5Cevaluator.py:72:exception>
AttributeError: 'Child' object has no attribute 'id_parent'
...because the attribute lookup on Child is attempted using the column
name, rather than the attribute name. The actual delete action works
fine when I switch the strategy to False or "fetch", or if there are
no Child objects in the session (so no evaluation is invoked).
As you can see, this is v0.9.7, but I've not seen anything relevant in
the changelog since then.
Cheers,
Steve.
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