Jonathan Vanasco <jvana...@gmail.com> writes: > On Thursday, January 5, 2017 at 8:34:52 PM UTC-5, Daniel Kraus wrote: >> >> The use-case is that I have a big model with lots of complex >> relationships but 90% of the time I don't need the data from those. > > If I'm reading your question correctly, most of what sqlalchemy does (and > excels at) is specifically keeping people from doing what you're trying to > do.
I think you got me wrong then. > It seems like you're trying to avoid all the work that is done to > ensure data integrity across sessions and transactions. (Which is a common > need) Nope, I just want to use a cache where I only store only the DB row for my model and not all data from relation tables as well. > Read up on the `merge` session > method > (http://docs.sqlalchemy.org/en/latest/orm/session_state_management.html#merging) > The dogpile caching section is largely based on that (though goes beyond > it). > > You would do something like this: > > user = User(**userdata) > user = session.merge(user) > > That will merge the user object into the session (and return the merged > object). Thanks. > You will run into problems if your cached data is incomplete though -- > AFAIK, there is no way to tell sqlalchemy that you've only loaded data for > certain columns. If you don't populate all the columns in your cache, but > have it in the db, I have no idea how to get that info from the db. `session.merge` populates the missing attributes from the db. But in my case, where I have all the data and know it's up to date, I can even skip that one select and use the `load=False` parameter. So for my example I can (thanks to Mike's reply): make_transient_to_detached(user) user = session.merge(user, load=False) and after that I can do my `user.big_n_to_m_relation_data` and it will correctly query the db. Thanks, Daniel -- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
