do_orm_execute() (and freezing the results) totally allows for what I'm trying to do! Also I forgot to mention earlier, but this is only going to run in tests.
Thanks again for all the help, Tony On Friday, October 20, 2023 at 11:10:23 PM UTC+8 Mike Bayer wrote: > > > On Fri, Oct 20, 2023, at 10:46 AM, 'Tony Cosentini' via sqlalchemy wrote: > > Oh I see, thanks for clarifying. > > I'm trying to detect cases where we depend on the autoflush behavior. For > example, in the sample above, when the query runs with no_autoflush, we > won't get back any results (when previously we would get back one row). > It's a fairly large codebase, so I was trying to automate finding these > cases in order to add explicit flush calls when needed or just pass in the > pending object instead of running a query. > > > > there's not really an event for an object that just gets returned by a > query from the identity map. you would need to do something more drastic > like a do_orm_execute() hook that runs queries internally and then looks at > all the returned objects. i wouldnt put that in production. > > > > > > > > > Tony > > On Fri, Oct 20, 2023 at 10:42 PM Mike Bayer <[email protected]> > wrote: > > > > > On Fri, Oct 20, 2023, at 9:50 AM, 'Tony Cosentini' via sqlalchemy wrote: > > Weird, I did try that but I can't seem to trigger it. > > Here's a self-contained test: > https://gist.github.com/tonycosentini/4dee3478695d032ca67707b5e26739b6 > > > > the object was not affected in that query (that is, not mutated). if you > change the query to this: > > table_one_instances = > session.query(TableOne).populate_existing().all() > > then the refresh event is triggered. > > Im not really following what kind of bug you are trying to detect. > > > > I have the event listener set to just crash, but it never triggers. > > On Fri, Oct 20, 2023 at 9:20 PM Mike Bayer <[email protected]> > wrote: > > > > > On Fri, Oct 20, 2023, at 8:08 AM, 'Tony Cosentini' via sqlalchemy wrote: > > Hi, > > Is there any way to listen for an event for when a query result gets > merged into a pre-existing object in the session? > > > this is the refresh event: > > > https://docs.sqlalchemy.org/en/20/orm/events.html#sqlalchemy.orm.InstanceEvents.refresh > > > > I'm working on disabling autoflush for some of our codebase (mostly to cut > down on queries on a high QPS path), but before doing that I want to write > a utility to detect when we read data that was flushed via autoflush to cut > down on any potential bugs. > > What I'd like to do is this (while autoflush is still enabled): > > table_one = TableOne(name='test') > session.add(table_one) # Track this object as pending a flush via the > before_* listeners, this is working as expected. > > table_two_instances = session.query(TableTwo).all() # All good, doesn't do > anything with the table_one instance created earlier > > table_one_instances = session.query(TableOne).all() # I would like to log > a warning here as the results of this query depend on a flush happening. > What I'm hoping to do is detect that one of the rows coming back is the > same object that was flagged earlier, but I can't see to find the correct > event to use. > > > you probably want to also use refresh_flush also, which will be invoked > for column defaults that are populated on the object > > > https://docs.sqlalchemy.org/en/20/orm/events.html#sqlalchemy.orm.InstanceEvents.refresh_flush > > > > > > Is this possible? I can't seem to find the appropriate event that would > trigger when the results from the .all() query get merged back in with the > existing objects in the session. > > > that's the refresh event > > > > -- > 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. 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