records update/added by a mapper extension during a flush are not flushed

[Former user]

If you use a mapper extension which updates other records or adds new records these are not written to disk until a later flush call. Hence the disk copy is not fully written.

This was spotted during some unit tests which did DBSession.flush/DBSession.expunge_all before testing the data had been written by reading from the database.

[Mike Bayer]

this is by design. If you'd like to affect the contents of a flush within an extension, use SessionExtension.before_flush().

[Mike Bayer]

and it is documented:

http://www.sqlalchemy.org/docs/05/reference/orm/interfaces.html#sqlalchemy.orm.interfaces.MapperExtension.before_update