This release contains backwards-incompatible changes in the way Peewee
initializes connections to the underlying database driver. Previously, peewee
implemented autocommit semantics on-top of the existing DB-API transactional
workflow. Going forward, Peewee instead places the DB-API driver into
autocommit mode directly.
Why this change?
Previously, Peewee emulated autocommit behavior for top-level queries issued
outside of a transaction. This necessitated a number of checks which had to be
performed each time a query was executed, so as to ensure that we didn't end up
with uncommitted writes or, conversely, idle read transactions. By running the
underlying driver in autocommit mode, we can eliminate all these checks, since
we are already managing transactions ourselves.
Behaviorally, there should be no change -- Peewee will still treat top-level
queries outside of transactions as being autocommitted, while queries inside of
atomic() / with db: blocks are implicitly committed at the end of the
block, or rolled-back if an exception occurs.
How might this affect me?
- If you are using the underlying database connection or cursors, e.g. via
Database.connection()orDatabase.cursor(), your queries will now be executed in autocommit mode. - The
commit=argument is deprecated for thecursor(),execute()andexecute_sql()methods. - If you have a custom
Databaseimplementation (whether for a database that is not officially supported, or for the purpose of overriding default behaviors), you will want to ensure that your connections are opened in autocommit mode.
Other changes:
- Some fixes to help with packaging in Python 3.11.
- MySQL
get_columns()implementation now returns columns in their declared order.