On Wed, Oct 10, 2018 at 1:32 PM Alex Rothberg <[email protected]> wrote:
>
> Well the other way doesn't quite work as if I mark none of the columns as 
> foreign in the primary join, sqla then assumes / guesses all of them are.

that is the case, that is code that has changed a lot over the years
so it has a lot of baggage.



>
> Let me test with passive.
>
> On Wed, Oct 10, 2018, 13:30 Mike Bayer <[email protected]> wrote:
>>
>> On Wed, Oct 10, 2018 at 1:27 PM Alex Rothberg <[email protected]> wrote:
>> >
>> > And I'll reiterate, not worth doing it all from the original single 
>> > relationship (ie not needing to either add more relationships, have 
>> > warnings or use the more obscure feature you outlined)? Seems like that 
>> > would be cleaner in code.
>>
>> you mean take the viewonly=True off the existing relationship?  sure
>> you can do that.  but if you mutate the elements in that collection,
>> you can incur a change that is conflicting with the other objects.
>> that's why I suggested making the non-viewonly a private member, but
>> either way works.
>>
>>
>> >
>> > On Wed, Oct 10, 2018, 13:17 Mike Bayer <[email protected]> wrote:
>> >>
>> >> the raise load issue is because without passive_deletes, it has to
>> >> load the collection to make sure those objects are all updated.
>> >> passive_deletes fixes, now you just have a warning.  or use the unit
>> >> of work recipe which is more direct.
>> >> On Wed, Oct 10, 2018 at 1:15 PM Alex Rothberg <[email protected]> 
>> >> wrote:
>> >> >
>> >> > Not just for warning. Also this raise load issue. yes, i see that I 
>> >> > can't mark none. If I could though, that would be awesome since I think 
>> >> > it would solve this problem? I can test by setting one foreign and 
>> >> > seeing if that works.
>> >> >
>> >> > On Wednesday, October 10, 2018 at 1:13:32 PM UTC-4, Mike Bayer wrote:
>> >> >>
>> >> >> On Wed, Oct 10, 2018 at 12:56 PM Alex Rothberg <[email protected]> 
>> >> >> wrote:
>> >> >> >
>> >> >> > let me get that. in the meantime, what are your thoughts on just 
>> >> >> > removing the view only from the original relationship and then using 
>> >> >> > an explicit primary join where none of the columns are marked 
>> >> >> > foreign? Theoretically that should solve this problem, no?
>> >> >>
>> >> >> is this just for the warning?    I don't think the relationship() can
>> >> >> be set up with no columns marked as foreign, it takes that as a cue
>> >> >> that it should figure out the "foreign" columns on its own.
>> >> >>
>> >> >> There's another way to make sure Employee is always dependent on
>> >> >> FundTitle but it's a little bit off-label.     Add the dependency you
>> >> >> want directly into the unit of work:
>> >> >>
>> >> >> from sqlalchemy.orm import unitofwork
>> >> >> from sqlalchemy import event
>> >> >>
>> >> >>
>> >> >> @event.listens_for(Session, "before_flush")
>> >> >> def _add_dep(session, context, objects):
>> >> >>     context.dependencies.update([
>> >> >>         (
>> >> >>             unitofwork.SaveUpdateAll(context, inspect(FundTitle)),
>> >> >>             unitofwork.SaveUpdateAll(context, inspect(Employee))
>> >> >>         )
>> >> >>     ])
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >> >
>> >> >> > On Wednesday, October 10, 2018 at 12:41:25 PM UTC-4, Alex Rothberg 
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> Is it possible to specific a non viewonly relationship in which I 
>> >> >> >> have a primary join specified in which none of the fk's are marked 
>> >> >> >> "foreign"? ie where I can mark the relationship dependancy but it 
>> >> >> >> wont set any columns? It looks like there may be some logic in sqla 
>> >> >> >> that assume all columns are fk if none are specified as foreign?
>> >> >> >>
>> >> >> >> On Wednesday, October 10, 2018 at 11:56:49 AM UTC-4, Alex Rothberg 
>> >> >> >> wrote:
>> >> >> >>>
>> >> >> >>> So one minor issue and one big issue with that solution:
>> >> >> >>> 1. minor issue, I now get these: SAWarning: relationship 'XXXX' 
>> >> >> >>> will copy columnYYYY to column ZZZZ, which conflicts with 
>> >> >> >>> relationship(s): '....
>> >> >> >>> 2. major issue, I use raiseload("*") and now I start seeing: 
>> >> >> >>> sqlalchemy.exc.InvalidRequestError: 'Employee._ft_for_dependency' 
>> >> >> >>> is not available due to lazy='raise'
>> >> >> >>>
>> >> >> >>> On Wednesday, October 10, 2018 at 9:57:55 AM UTC-4, Mike Bayer 
>> >> >> >>> wrote:
>> >> >> >>>>
>> >> >> >>>> On Tue, Oct 9, 2018 at 6:45 PM Alex Rothberg <[email protected]> 
>> >> >> >>>> wrote:
>> >> >> >>>> >
>> >> >> >>>> > Okay with some small tweaks to your original code, I am able to 
>> >> >> >>>> > show the issue I am having. comment out flush to see issue:
>> >> >> >>>>
>> >> >> >>>> so what you're doing here is making Employee dependent on 
>> >> >> >>>> FundTitle,
>> >> >> >>>> which makes this a little out of the ordinary but this is fine.   
>> >> >> >>>> You
>> >> >> >>>> need to give the ORM a clue that this dependency exists, since it
>> >> >> >>>> never looks at foreign key constraints unless you tell it to.
>> >> >> >>>> Adding a relationship to FundTitle that doesn't have 
>> >> >> >>>> viewonly=True is
>> >> >> >>>> an easy way to do this, there's no need to ever make use of the
>> >> >> >>>> relationship otherwise:
>> >> >> >>>>
>> >> >> >>>> class Employee(Base):
>> >> >> >>>>     __tablename__ = 'employee'
>> >> >> >>>>
>> >> >> >>>>     # ...
>> >> >> >>>>     fund_title = relationship(FundTitle, viewonly=True)
>> >> >> >>>>
>> >> >> >>>>     _ft_for_dependency = relationship(FundTitle)
>> >> >> >>>>
>> >> >> >>>>     __table_args__ = (
>> >> >> >>>>         ForeignKeyConstraint(
>> >> >> >>>>             (title_id, department_id, fund_id),
>> >> >> >>>>             (FundTitle.title_id, FundTitle.department_id, 
>> >> >> >>>> FundTitle.fund_id)
>> >> >> >>>>         ),
>> >> >> >>>>     )
>> >> >> >>>>
>> >> >> >>>> then you can take the flush() out and there's no issue, as long as
>> >> >> >>>> you're always making sure that FundTitle object is present either 
>> >> >> >>>> in
>> >> >> >>>> the current Session or the row in the database exists.
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>> >
>> >> >> >>>> > from sqlalchemy import *
>> >> >> >>>> > from sqlalchemy.orm import *
>> >> >> >>>> > from sqlalchemy.ext.declarative import declarative_base
>> >> >> >>>> >
>> >> >> >>>> > Base = declarative_base()
>> >> >> >>>> >
>> >> >> >>>> >
>> >> >> >>>> > class Title(Base):
>> >> >> >>>> >     __tablename__ = 'title'
>> >> >> >>>> >     id = Column(Integer, primary_key=True)
>> >> >> >>>> >     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> > nullable=False)
>> >> >> >>>> >
>> >> >> >>>> >     department = relationship(lambda: Department)
>> >> >> >>>> >
>> >> >> >>>> >
>> >> >> >>>> > class Department(Base):
>> >> >> >>>> >     __tablename__ = 'department'
>> >> >> >>>> >     id = Column(Integer, primary_key=True)
>> >> >> >>>> >
>> >> >> >>>> >
>> >> >> >>>> > class Fund(Base):
>> >> >> >>>> >     __tablename__ = 'fund'
>> >> >> >>>> >     id = Column(Integer, primary_key=True)
>> >> >> >>>> >     title_id = Column(ForeignKey('title.id'), nullable=False)
>> >> >> >>>> >     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> > nullable=False)
>> >> >> >>>> >     department = relationship("Department")
>> >> >> >>>> >     title = relationship("Title")
>> >> >> >>>> >
>> >> >> >>>> >
>> >> >> >>>> > class FundTitle(Base):
>> >> >> >>>> >     __tablename__ = 'fund_title'
>> >> >> >>>> >     id = Column(Integer, primary_key=True)
>> >> >> >>>> >     title_id = Column(ForeignKey('title.id'), nullable=False)
>> >> >> >>>> >     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> > nullable=False)
>> >> >> >>>> >     fund_id = Column(ForeignKey('fund.id'), nullable=False)
>> >> >> >>>> >     department = relationship("Department")
>> >> >> >>>> >     title = relationship("Title")
>> >> >> >>>> >     fund = relationship("Fund")
>> >> >> >>>> >
>> >> >> >>>> >     __table_args__ = (
>> >> >> >>>> >         UniqueConstraint(
>> >> >> >>>> >             title_id, department_id, fund_id
>> >> >> >>>> >         ),
>> >> >> >>>> >     )
>> >> >> >>>> >
>> >> >> >>>> >
>> >> >> >>>> > class Employee(Base):
>> >> >> >>>> >     __tablename__ = 'employee'
>> >> >> >>>> >     id = Column(Integer, primary_key=True)
>> >> >> >>>> >     title_id = Column(ForeignKey('title.id'), nullable=False)
>> >> >> >>>> >     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> > nullable=False)
>> >> >> >>>> >     fund_id = Column(ForeignKey('fund.id'), nullable=False)
>> >> >> >>>> >
>> >> >> >>>> >     department = relationship(lambda: Department)
>> >> >> >>>> >     title = relationship("Title")
>> >> >> >>>> >     fund = relationship("Fund")
>> >> >> >>>> >
>> >> >> >>>> >     fund_title = relationship(FundTitle, viewonly=True)
>> >> >> >>>> >
>> >> >> >>>> >
>> >> >> >>>> >     __table_args__ = (
>> >> >> >>>> >         ForeignKeyConstraint(
>> >> >> >>>> >             (title_id, department_id, fund_id), 
>> >> >> >>>> > (FundTitle.title_id, FundTitle.department_id, FundTitle.fund_id)
>> >> >> >>>> >         ),
>> >> >> >>>> >     )
>> >> >> >>>> >
>> >> >> >>>> >
>> >> >> >>>> > e = create_engine("postgresql://localhost/test_issue", 
>> >> >> >>>> > echo=False)
>> >> >> >>>> >
>> >> >> >>>> > # Base.metadata.drop_all(e)
>> >> >> >>>> > Base.metadata.create_all(e)
>> >> >> >>>> >
>> >> >> >>>> > s = Session(e)
>> >> >> >>>> > # s.rollback()
>> >> >> >>>> >
>> >> >> >>>> > while True:
>> >> >> >>>> >     d1 = Department()
>> >> >> >>>> >     t1 = Title(department=d1)
>> >> >> >>>> >     f1 = Fund(department=d1, title=t1)
>> >> >> >>>> >     ft1 = FundTitle(title=t1, department=d1, fund=f1)
>> >> >> >>>> >
>> >> >> >>>> >     s.add_all([d1, t1, f1,  ft1])
>> >> >> >>>> >
>> >> >> >>>> >     s.flush()
>> >> >> >>>> >
>> >> >> >>>> >     e1 = Employee(title=t1, department=d1, fund=f1)
>> >> >> >>>> >
>> >> >> >>>> >     s.add_all([e1,])
>> >> >> >>>> >     s.commit()
>> >> >> >>>> >
>> >> >> >>>> > On Tuesday, October 9, 2018 at 12:20:30 PM UTC-4, Mike Bayer 
>> >> >> >>>> > wrote:
>> >> >> >>>> >>
>> >> >> >>>> >> On Tue, Oct 9, 2018 at 10:44 AM Alex Rothberg 
>> >> >> >>>> >> <[email protected]> wrote:
>> >> >> >>>> >> >
>> >> >> >>>> >> > In looking at what you wrote doesn't this cause an fk 
>> >> >> >>>> >> > violation (it does for me):
>> >> >> >>>> >> > 2018-10-08 10:18:38,760 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> > INSERT INTO employee (title_id, department_id, fund_id) 
>> >> >> >>>> >> > VALUES (%(title_id)s, %(department_id)s, %(fund_id)s) 
>> >> >> >>>> >> > RETURNING employee.id
>> >> >> >>>> >> > 2018-10-08 10:18:38,763 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> > INSERT INTO fund_title (title_id, department_id, fund_id) 
>> >> >> >>>> >> > VALUES (%(title_id)s, %(department_id)s, %(fund_id)s) 
>> >> >> >>>> >> > RETURNING fund_title.id
>> >> >> >>>> >> >
>> >> >> >>>> >> > in that a a (non deferred) fk is violated between employee 
>> >> >> >>>> >> > and fund_title ?
>> >> >> >>>> >>
>> >> >> >>>> >> see we need to see how youve laid out your 
>> >> >> >>>> >> ForeignKeyConstraints, if
>> >> >> >>>> >> they are composite and overlapping, there are additional 
>> >> >> >>>> >> options that
>> >> >> >>>> >> may be needed (specifically the post_update flag).  you'll 
>> >> >> >>>> >> note I laid
>> >> >> >>>> >> out all FKs as single column.
>> >> >> >>>> >>
>> >> >> >>>> >> >
>> >> >> >>>> >> > On Mon, Oct 8, 2018 at 10:20 AM Mike Bayer 
>> >> >> >>>> >> > <[email protected]> wrote:
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> On Sun, Oct 7, 2018 at 7:11 PM Alex Rothberg 
>> >> >> >>>> >> >> <[email protected]> wrote:
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > Okay so I investigated / thought about this further. The 
>> >> >> >>>> >> >> > issue is that while I do have a relationship between the 
>> >> >> >>>> >> >> > various models, some of the relationships are viewonly 
>> >> >> >>>> >> >> > since I have overlapping fks.
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > For example I have a model Employee, which has fks: 
>> >> >> >>>> >> >> > department_id, title_id, and fund_id. The related models 
>> >> >> >>>> >> >> > are Department (fk department_id), Title (fk 
>> >> >> >>>> >> >> > department_id and title_id) , Fund (fk fund_id) and 
>> >> >> >>>> >> >> > FundTitle (fk department_id, title_id and fund_id). I 
>> >> >> >>>> >> >> > have set FundTitle to viewonly. When updating / creating 
>> >> >> >>>> >> >> > an Employee, I do create and add a new FundTitle to the 
>> >> >> >>>> >> >> > session, however I don't assign it to the employee as the 
>> >> >> >>>> >> >> > relationship is viewonly. If I don't flush before making 
>> >> >> >>>> >> >> > the assignment, the final flush / commit attempts to 
>> >> >> >>>> >> >> > update / create the employee before creating the 
>> >> >> >>>> >> >> > FundTitle.
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> let's work with source code that is runnable (e.g. MCVE).   
>> >> >> >>>> >> >> Below is
>> >> >> >>>> >> >> the model that it seems you are describing, and then 
>> >> >> >>>> >> >> there's a
>> >> >> >>>> >> >> demonstration of assembly of all those components using 
>> >> >> >>>> >> >> relationships,
>> >> >> >>>> >> >> a single flush and it all goes in in the correct order, all 
>> >> >> >>>> >> >> FKs are
>> >> >> >>>> >> >> nullable=False.
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> from sqlalchemy import *
>> >> >> >>>> >> >> from sqlalchemy.orm import *
>> >> >> >>>> >> >> from sqlalchemy.ext.declarative import declarative_base
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> Base = declarative_base()
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> class Employee(Base):
>> >> >> >>>> >> >>     __tablename__ = 'employee'
>> >> >> >>>> >> >>     id = Column(Integer, primary_key=True)
>> >> >> >>>> >> >>     title_id = Column(ForeignKey('title.id'), 
>> >> >> >>>> >> >> nullable=False)
>> >> >> >>>> >> >>     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> >> >> nullable=False)
>> >> >> >>>> >> >>     fund_id = Column(ForeignKey('fund.id'), nullable=False)
>> >> >> >>>> >> >>     department = relationship("Department")
>> >> >> >>>> >> >>     title = relationship("Title")
>> >> >> >>>> >> >>     fund = relationship("Fund")
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> class Title(Base):
>> >> >> >>>> >> >>     __tablename__ = 'title'
>> >> >> >>>> >> >>     id = Column(Integer, primary_key=True)
>> >> >> >>>> >> >>     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> >> >> nullable=False)
>> >> >> >>>> >> >>     department = relationship("Department")
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> class Department(Base):
>> >> >> >>>> >> >>     __tablename__ = 'department'
>> >> >> >>>> >> >>     id = Column(Integer, primary_key=True)
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> class Fund(Base):
>> >> >> >>>> >> >>     __tablename__ = 'fund'
>> >> >> >>>> >> >>     id = Column(Integer, primary_key=True)
>> >> >> >>>> >> >>     title_id = Column(ForeignKey('title.id'), 
>> >> >> >>>> >> >> nullable=False)
>> >> >> >>>> >> >>     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> >> >> nullable=False)
>> >> >> >>>> >> >>     department = relationship("Department")
>> >> >> >>>> >> >>     title = relationship("Title")
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> class FundTitle(Base):
>> >> >> >>>> >> >>     __tablename__ = 'fund_title'
>> >> >> >>>> >> >>     id = Column(Integer, primary_key=True)
>> >> >> >>>> >> >>     title_id = Column(ForeignKey('title.id'), 
>> >> >> >>>> >> >> nullable=False)
>> >> >> >>>> >> >>     department_id = Column(ForeignKey('department.id'), 
>> >> >> >>>> >> >> nullable=False)
>> >> >> >>>> >> >>     fund_id = Column(ForeignKey('fund.id'), nullable=False)
>> >> >> >>>> >> >>     department = relationship("Department")
>> >> >> >>>> >> >>     title = relationship("Title")
>> >> >> >>>> >> >>     fund = relationship("Fund")
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> e = 
>> >> >> >>>> >> >> create_engine("postgresql://scott:tiger@localhost/test", 
>> >> >> >>>> >> >> echo=True)
>> >> >> >>>> >> >> Base.metadata.create_all(e)
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> s = Session(e)
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> d1 = Department()
>> >> >> >>>> >> >> t1 = Title(department=d1)
>> >> >> >>>> >> >> f1 = Fund(department=d1, title=t1)
>> >> >> >>>> >> >> ft1 = FundTitle(title=t1, department=d1, fund=f1)
>> >> >> >>>> >> >> e1 = Employee(title=t1, department=d1, fund=f1)
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> s.add_all([d1, t1, f1, ft1, e1])
>> >> >> >>>> >> >> s.commit()
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> the INSERTs can be ordered naturally here and the unit of 
>> >> >> >>>> >> >> work will do
>> >> >> >>>> >> >> that for you if you use relationship:
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> BEGIN (implicit)
>> >> >> >>>> >> >> 2018-10-08 10:18:38,750 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> INSERT INTO
>> >> >> >>>> >> >> department DEFAULT VALUES RETURNING department.id
>> >> >> >>>> >> >> 2018-10-08 10:18:38,750 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> {}
>> >> >> >>>> >> >> 2018-10-08 10:18:38,753 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> INSERT INTO
>> >> >> >>>> >> >> title (department_id) VALUES (%(department_id)s) RETURNING 
>> >> >> >>>> >> >> title.id
>> >> >> >>>> >> >> 2018-10-08 10:18:38,753 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> {'department_id': 1}
>> >> >> >>>> >> >> 2018-10-08 10:18:38,757 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> INSERT INTO
>> >> >> >>>> >> >> fund (title_id, department_id) VALUES (%(title_id)s,
>> >> >> >>>> >> >> %(department_id)s) RETURNING fund.id
>> >> >> >>>> >> >> 2018-10-08 10:18:38,757 INFO sqlalchemy.engine.base.Engine
>> >> >> >>>> >> >> {'title_id': 1, 'department_id': 1}
>> >> >> >>>> >> >> 2018-10-08 10:18:38,760 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> INSERT INTO
>> >> >> >>>> >> >> employee (title_id, department_id, fund_id) VALUES 
>> >> >> >>>> >> >> (%(title_id)s,
>> >> >> >>>> >> >> %(department_id)s, %(fund_id)s) RETURNING employee.id
>> >> >> >>>> >> >> 2018-10-08 10:18:38,761 INFO sqlalchemy.engine.base.Engine
>> >> >> >>>> >> >> {'title_id': 1, 'department_id': 1, 'fund_id': 1}
>> >> >> >>>> >> >> 2018-10-08 10:18:38,763 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> INSERT INTO
>> >> >> >>>> >> >> fund_title (title_id, department_id, fund_id) VALUES 
>> >> >> >>>> >> >> (%(title_id)s,
>> >> >> >>>> >> >> %(department_id)s, %(fund_id)s) RETURNING fund_title.id
>> >> >> >>>> >> >> 2018-10-08 10:18:38,764 INFO sqlalchemy.engine.base.Engine
>> >> >> >>>> >> >> {'title_id': 1, 'department_id': 1, 'fund_id': 1}
>> >> >> >>>> >> >> 2018-10-08 10:18:38,766 INFO sqlalchemy.engine.base.Engine 
>> >> >> >>>> >> >> COMMIT
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > On Tuesday, September 18, 2018 at 9:02:30 AM UTC-4, Mike 
>> >> >> >>>> >> >> > Bayer wrote:
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> if there are no dependencies between two particular 
>> >> >> >>>> >> >> >> objects of
>> >> >> >>>> >> >> >> different classes, say A and B, then there is no 
>> >> >> >>>> >> >> >> deterministic
>> >> >> >>>> >> >> >> ordering between them.   For objects of the same class, 
>> >> >> >>>> >> >> >> they are
>> >> >> >>>> >> >> >> inserted in the order in which they were added to the 
>> >> >> >>>> >> >> >> Session.
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> the correct way to solve this problem in SQLAlchemy is 
>> >> >> >>>> >> >> >> to use
>> >> >> >>>> >> >> >> relationship() fully.  I know you've stated that these 
>> >> >> >>>> >> >> >> objects have a
>> >> >> >>>> >> >> >> relationship() between them but you have to actually use 
>> >> >> >>>> >> >> >> it, that is:
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> obj_a = A()
>> >> >> >>>> >> >> >> obj_b = B()
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> obj_a.some_relationship = obj_b   # will definitely 
>> >> >> >>>> >> >> >> flush correctly
>> >> >> >>>> >> >> >> unless there is a bug
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> OTOH if you are only using foreign key attributes, the 
>> >> >> >>>> >> >> >> ORM does *not*
>> >> >> >>>> >> >> >> have any idea in how it should be flushing these:
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> obj_a = A()
>> >> >> >>>> >> >> >> obj_b = B()
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> obj_a.some_fk = obj_b.some_id    # ORM doesn't care 
>> >> >> >>>> >> >> >> about this, no
>> >> >> >>>> >> >> >> ordering is implied
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> since you said you're not setting any IDs, I'm not sure 
>> >> >> >>>> >> >> >> how you could
>> >> >> >>>> >> >> >> be doing the above.
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >>
>> >> >> >>>> >> >> >> On Tue, Sep 18, 2018 at 5:53 AM Simon King 
>> >> >> >>>> >> >> >> <[email protected]> wrote:
>> >> >> >>>> >> >> >> >
>> >> >> >>>> >> >> >> > It's not something I've ever looked into, but I'm not 
>> >> >> >>>> >> >> >> > aware of any
>> >> >> >>>> >> >> >> > debugging options here, no. You'd probably want to 
>> >> >> >>>> >> >> >> > start by scattering
>> >> >> >>>> >> >> >> > print statements around the UOWTransaction class
>> >> >> >>>> >> >> >> > (https://bitbucket.org/zzzeek/sqlalchemy/src/c94d67892e68ac317d72eb202cca427084b3ca74/lib/sqlalchemy/orm/unitofwork.py?at=master&fileviewer=file-view-default#unitofwork.py-111)
>> >> >> >>>> >> >> >> >
>> >> >> >>>> >> >> >> > Looking at that code made me wonder whether you've set 
>> >> >> >>>> >> >> >> > any particular
>> >> >> >>>> >> >> >> > cascade options on your relationship; I'm not sure if 
>> >> >> >>>> >> >> >> > cascade options
>> >> >> >>>> >> >> >> > affect the dependency calculation.
>> >> >> >>>> >> >> >> >
>> >> >> >>>> >> >> >> > Simon
>> >> >> >>>> >> >> >> >
>> >> >> >>>> >> >> >> > On Tue, Sep 18, 2018 at 5:28 AM Alex Rothberg 
>> >> >> >>>> >> >> >> > <[email protected]> wrote:
>> >> >> >>>> >> >> >> > >
>> >> >> >>>> >> >> >> > > In order to guide me in stripping down this code to 
>> >> >> >>>> >> >> >> > > produce an example for positing, are there any 
>> >> >> >>>> >> >> >> > > options / flags / introspections I can turn on to 
>> >> >> >>>> >> >> >> > > understand how sql makes decisions about the order 
>> >> >> >>>> >> >> >> > > in which is writes statements to the DB?
>> >> >> >>>> >> >> >> > >
>> >> >> >>>> >> >> >> > > On Friday, September 14, 2018 at 10:13:45 AM UTC-4, 
>> >> >> >>>> >> >> >> > > Simon King wrote:
>> >> >> >>>> >> >> >> > >>
>> >> >> >>>> >> >> >> > >> In that case can you show us the code that is 
>> >> >> >>>> >> >> >> > >> causing the problem?
>> >> >> >>>> >> >> >> > >> On Fri, Sep 14, 2018 at 2:55 PM Alex Rothberg 
>> >> >> >>>> >> >> >> > >> <[email protected]> wrote:
>> >> >> >>>> >> >> >> > >> >
>> >> >> >>>> >> >> >> > >> > I am not generating any IDs myself and I already 
>> >> >> >>>> >> >> >> > >> > have relationships between the models.
>> >> >> >>>> >> >> >> > >> >
>> >> >> >>>> >> >> >> > >> > On Friday, September 14, 2018 at 4:33:08 AM 
>> >> >> >>>> >> >> >> > >> > UTC-4, Simon King wrote:
>> >> >> >>>> >> >> >> > >> >>
>> >> >> >>>> >> >> >> > >> >> On Thu, Sep 13, 2018 at 10:50 PM Alex Rothberg 
>> >> >> >>>> >> >> >> > >> >> <[email protected]> wrote:
>> >> >> >>>> >> >> >> > >> >> >
>> >> >> >>>> >> >> >> > >> >> > Is it possible to hint at sqla the order in 
>> >> >> >>>> >> >> >> > >> >> > which it should write out changes to the DB?
>> >> >> >>>> >> >> >> > >> >> >
>> >> >> >>>> >> >> >> > >> >> > I am having issues in which I add two new 
>> >> >> >>>> >> >> >> > >> >> > objects to a session, a and b where a depends 
>> >> >> >>>> >> >> >> > >> >> > on b, but sqla is flushing a before b leading 
>> >> >> >>>> >> >> >> > >> >> > to an fk issue. I can solve this a few ways: 
>> >> >> >>>> >> >> >> > >> >> > explicitly calling flush after adding b, or 
>> >> >> >>>> >> >> >> > >> >> > changing the fk constraint to be initially 
>> >> >> >>>> >> >> >> > >> >> > deferred. Ideally I would not have to do 
>> >> >> >>>> >> >> >> > >> >> > either of these.
>> >> >> >>>> >> >> >> > >> >> >
>> >> >> >>>> >> >> >> > >> >>
>> >> >> >>>> >> >> >> > >> >> If you have configured a relationship between 
>> >> >> >>>> >> >> >> > >> >> the two classes
>> >> >> >>>> >> >> >> > >> >> (http://docs.sqlalchemy.org/en/latest/orm/tutorial.html#building-a-relationship),
>> >> >> >>>> >> >> >> > >> >> and you've linked the objects together using 
>> >> >> >>>> >> >> >> > >> >> that relationship (a.b =
>> >> >> >>>> >> >> >> > >> >> b), then SQLAlchemy will flush them in the 
>> >> >> >>>> >> >> >> > >> >> correct order. If you are
>> >> >> >>>> >> >> >> > >> >> generating your IDs in Python and assigning them 
>> >> >> >>>> >> >> >> > >> >> to the primary and
>> >> >> >>>> >> >> >> > >> >> foreign key columns directly, SQLAlchemy 
>> >> >> >>>> >> >> >> > >> >> probably won't understand the
>> >> >> >>>> >> >> >> > >> >> dependency.
>> >> >> >>>> >> >> >> > >> >>
>> >> >> >>>> >> >> >> > >> >> Does using a relationship fix your problem?
>> >> >> >>>> >> >> >> > >> >>
>> >> >> >>>> >> >> >> > >> >> Simon
>> >> >> >>>> >> >> >> > >> >
>> >> >> >>>> >> >> >> > >> > --
>> >> >> >>>> >> >> >> > >> > SQLAlchemy -
>> >> >> >>>> >> >> >> > >> > The Python SQL Toolkit and Object Relational 
>> >> >> >>>> >> >> >> > >> > Mapper
>> >> >> >>>> >> >> >> > >> >
>> >> >> >>>> >> >> >> > >> > http://www.sqlalchemy.org/
>> >> >> >>>> >> >> >> > >> >
>> >> >> >>>> >> >> >> > >> > To post example code, please provide an MCVE: 
>> >> >> >>>> >> >> >> > >> > Minimal, Complete, and Verifiable Example. See 
>> >> >> >>>> >> >> >> > >> > http://stackoverflow.com/help/mcve for a full 
>> >> >> >>>> >> >> >> > >> > description.
>> >> >> >>>> >> >> >> > >> > ---
>> >> >> >>>> >> >> >> > >> > You received this message because you are 
>> >> >> >>>> >> >> >> > >> > subscribed to the Google Groups "sqlalchemy" 
>> >> >> >>>> >> >> >> > >> > group.
>> >> >> >>>> >> >> >> > >> > To unsubscribe from this group and stop receiving 
>> >> >> >>>> >> >> >> > >> > emails from it, send an email to 
>> >> >> >>>> >> >> >> > >> > [email protected].
>> >> >> >>>> >> >> >> > >> > To post to this group, send email to 
>> >> >> >>>> >> >> >> > >> > [email protected].
>> >> >> >>>> >> >> >> > >> > Visit this group at 
>> >> >> >>>> >> >> >> > >> > https://groups.google.com/group/sqlalchemy.
>> >> >> >>>> >> >> >> > >> > For more options, visit 
>> >> >> >>>> >> >> >> > >> > https://groups.google.com/d/optout.
>> >> >> >>>> >> >> >> > >
>> >> >> >>>> >> >> >> > > --
>> >> >> >>>> >> >> >> > > SQLAlchemy -
>> >> >> >>>> >> >> >> > > The Python SQL Toolkit and Object Relational Mapper
>> >> >> >>>> >> >> >> > >
>> >> >> >>>> >> >> >> > > http://www.sqlalchemy.org/
>> >> >> >>>> >> >> >> > >
>> >> >> >>>> >> >> >> > > To post example code, please provide an MCVE: 
>> >> >> >>>> >> >> >> > > Minimal, Complete, and Verifiable Example. See 
>> >> >> >>>> >> >> >> > > http://stackoverflow.com/help/mcve for a full 
>> >> >> >>>> >> >> >> > > description.
>> >> >> >>>> >> >> >> > > ---
>> >> >> >>>> >> >> >> > > You received this message because you are subscribed 
>> >> >> >>>> >> >> >> > > to the Google Groups "sqlalchemy" group.
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>> >> >> >>>> >> >> >> > > emails from it, send an email to 
>> >> >> >>>> >> >> >> > > [email protected].
>> >> >> >>>> >> >> >> > > To post to this group, send email to 
>> >> >> >>>> >> >> >> > > [email protected].
>> >> >> >>>> >> >> >> > > Visit this group at 
>> >> >> >>>> >> >> >> > > https://groups.google.com/group/sqlalchemy.
>> >> >> >>>> >> >> >> > > For more options, visit 
>> >> >> >>>> >> >> >> > > https://groups.google.com/d/optout.
>> >> >> >>>> >> >> >> >
>> >> >> >>>> >> >> >> > --
>> >> >> >>>> >> >> >> > SQLAlchemy -
>> >> >> >>>> >> >> >> > The Python SQL Toolkit and Object Relational Mapper
>> >> >> >>>> >> >> >> >
>> >> >> >>>> >> >> >> > http://www.sqlalchemy.org/
>> >> >> >>>> >> >> >> >
>> >> >> >>>> >> >> >> > To post example code, please provide an MCVE: Minimal, 
>> >> >> >>>> >> >> >> > Complete, and Verifiable Example.  See  
>> >> >> >>>> >> >> >> > http://stackoverflow.com/help/mcve for a full 
>> >> >> >>>> >> >> >> > description.
>> >> >> >>>> >> >> >> > ---
>> >> >> >>>> >> >> >> > You received this message because you are subscribed 
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>> >> >> >>>> >> >> >> > [email protected].
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>> >> >> >>>> >> >> >> > Visit this group at 
>> >> >> >>>> >> >> >> > https://groups.google.com/group/sqlalchemy.
>> >> >> >>>> >> >> >> > For more options, visit 
>> >> >> >>>> >> >> >> > https://groups.google.com/d/optout.
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > --
>> >> >> >>>> >> >> > SQLAlchemy -
>> >> >> >>>> >> >> > The Python SQL Toolkit and Object Relational Mapper
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > http://www.sqlalchemy.org/
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > To post example code, please provide an MCVE: Minimal, 
>> >> >> >>>> >> >> > Complete, and Verifiable Example. See 
>> >> >> >>>> >> >> > http://stackoverflow.com/help/mcve for a full description.
>> >> >> >>>> >> >> > ---
>> >> >> >>>> >> >> > You received this message because you are subscribed to 
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>> >> >> >>>> >> >> > https://groups.google.com/d/optout.
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> --
>> >> >> >>>> >> >> SQLAlchemy -
>> >> >> >>>> >> >> The Python SQL Toolkit and Object Relational Mapper
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> http://www.sqlalchemy.org/
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> To post example code, please provide an MCVE: Minimal, 
>> >> >> >>>> >> >> Complete, and Verifiable Example.  See  
>> >> >> >>>> >> >> http://stackoverflow.com/help/mcve for a full description.
>> >> >> >>>> >> >> ---
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>> >> >> >>>> >> >
>> >> >> >>>> >> > --
>> >> >> >>>> >> > SQLAlchemy -
>> >> >> >>>> >> > The Python SQL Toolkit and Object Relational Mapper
>> >> >> >>>> >> >
>> >> >> >>>> >> > http://www.sqlalchemy.org/
>> >> >> >>>> >> >
>> >> >> >>>> >> > To post example code, please provide an MCVE: Minimal, 
>> >> >> >>>> >> > Complete, and Verifiable Example. See 
>> >> >> >>>> >> > http://stackoverflow.com/help/mcve for a full description.
>> >> >> >>>> >> > ---
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>> >> >> >>>> >
>> >> >> >>>> > --
>> >> >> >>>> > SQLAlchemy -
>> >> >> >>>> > The Python SQL Toolkit and Object Relational Mapper
>> >> >> >>>> >
>> >> >> >>>> > http://www.sqlalchemy.org/
>> >> >> >>>> >
>> >> >> >>>> > To post example code, please provide an MCVE: Minimal, 
>> >> >> >>>> > Complete, and Verifiable Example. See 
>> >> >> >>>> > http://stackoverflow.com/help/mcve for a full description.
>> >> >> >>>> > ---
>> >> >> >>>> > You received this message because you are subscribed to the 
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>> >> >> >
>> >> >> > --
>> >> >> > SQLAlchemy -
>> >> >> > The Python SQL Toolkit and Object Relational Mapper
>> >> >> >
>> >> >> > http://www.sqlalchemy.org/
>> >> >> >
>> >> >> > To post example code, please provide an MCVE: Minimal, Complete, and 
>> >> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a 
>> >> >> > full description.
>> >> >> > ---
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>> >> >
>> >> > --
>> >> > SQLAlchemy -
>> >> > The Python SQL Toolkit and Object Relational Mapper
>> >> >
>> >> > http://www.sqlalchemy.org/
>> >> >
>> >> > To post example code, please provide an MCVE: Minimal, Complete, and 
>> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
>> >> > description.
>> >> > ---
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>> >>
>> >> --
>> >> SQLAlchemy -
>> >> The Python SQL Toolkit and Object Relational Mapper
>> >>
>> >> http://www.sqlalchemy.org/
>> >>
>> >> To post example code, please provide an MCVE: Minimal, Complete, and 
>> >> Verifiable Example.  See  http://stackoverflow.com/help/mcve for a full 
>> >> description.
>> >> ---
>> >> You received this message because you are subscribed to a topic in the 
>> >> Google Groups "sqlalchemy" group.
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>> >
>> > --
>> > SQLAlchemy -
>> > The Python SQL Toolkit and Object Relational Mapper
>> >
>> > http://www.sqlalchemy.org/
>> >
>> > To post example code, please provide an MCVE: Minimal, Complete, and 
>> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
>> > description.
>> > ---
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>>
>> --
>> SQLAlchemy -
>> The Python SQL Toolkit and Object Relational Mapper
>>
>> http://www.sqlalchemy.org/
>>
>> To post example code, please provide an MCVE: Minimal, Complete, and 
>> Verifiable Example.  See  http://stackoverflow.com/help/mcve for a full 
>> description.
>> ---
>> You received this message because you are subscribed to a topic in the 
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>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and 
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
> description.
> ---
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-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
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