Revert multiple commits using a savepoint

[kaboo HD]

I am trying to test an endpoint in flask and I need to "refresh" the DB after some commits.

The idea I had was something like :

db=SQLAlchemy()

db.session.begin_nested()

db.session.add(Obj)
db.session.commit()

# some code where last commit is important

db.session.add(Obj2)
db.session.commit()

# some other code where last commit is important

db.session.rollback()

But it doesn't work unless I have a single commit.

Can you help me please :)

[Simon King]

Which version of SQLAlchemy are you using, and how are you creating
your engine? I believe savepoints are handled differently in SA 1.4 if
you are using the "future-style" engine.

Do these doc links help you at all?

https://docs.sqlalchemy.org/en/14/orm/session_transaction.html#nested-transaction

"""
Calling the Session.commit() or Connection.commit() methods will
always commit the outermost transaction; this is a SQLAlchemy 2.0
specific behavior that is reversed from the 1.x series.
"""

https://docs.sqlalchemy.org/en/14/orm/session_transaction.html#session-subtransactions

"""
The “subtransaction” pattern that was often used with autocommit mode
is also deprecated in 1.4. This pattern allowed the use of the
Session.begin() method when a transaction were already begun,
resulting in a construct called a “subtransaction”, which was
essentially a block that would prevent the Session.commit() method
from actually committing.
"""

Simon

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