Regarding the lazy loading of deferred fields and foreign keys I wanted to mention I've been working on a third-party application that allows overriding the default behavior[0].
The project works by tainting objects retrieved from "sealed" querysets and having fields descriptors lookup whether or not the object is "sealed" on attribute access and warn the developer about it if it's the case. Warnings can be elevated to errors using `filterwarnings` when deemed appropriated (e.g. CI, staging). It has been an useful tool to assist in figuring out where `select_related()` and `prefetch_related()` should be used to adjust complex projects database interactions. I assume a similar pattern could be used to mark objects retrieved from `QuerySet.__aiter__` to prevent non-async queries from being performed on attribute accesses; on `Model._state.async = True` field descriptors would error out. Cheers, Simon P.-S. While the project might look complex most of the code takes care of the delicate tasks of replacing fields descriptors once models are configured which could be significantly simplified if it was part of Django core. [0] https://github.com/charettes/django-seal Le samedi 9 juin 2018 02:30:59 UTC-4, Josh Smeaton a écrit : > > I think most of what you've laid out sounds great and that pursuing async > Django is in the projects best interests. The sync to async and async to > sync wrappers that have come out of channels give me much more confidence > that this project is doable in a reasonable amount of time with backwards > compatibility being preserved. > > The only real concern I have at the moment is around your comments > regarding on demand foreign key traversal. If existing code running > synchronously is going to be impacted, that's going to be very difficult > for a lot of people. If it's only asynchronous traversal that'll have > issues, then I have no real concern, as on demand foreign key fetching is > usually a bug anyway. > > Having a brief read through the psycopg asynchronous docs[0], it looks > like a number of features will be impossible or troublesome to use, like > transactions, executemany, and named cursors (.iterator() with server side > cursors). We'd also need to investigate how pgbouncer would work in async > mode, as most large sites using postgres are also using pgbouncer. I would > expect support can only further improve, especially if there is a driver > like django pushing. Fallback would just be to run inside a thread pool > though, so it's not a blocker for the rest of the proposal. > > Very exciting times ahead! > > [0] http://initd.org/psycopg/docs/advanced.html#asynchronous-support > > On Monday, 4 June 2018 23:18:23 UTC+10, Andrew Godwin wrote: >> >> Hello everyone, >> >> For a while now I have been working on potential plans for making Django >> async-capable, and I finally have a plan I am reasonably happy with and >> which I think we can actually do. >> >> This proposed roadmap, in its great length, is here: >> >> https://www.aeracode.org/2018/06/04/django-async-roadmap/ >> >> I'd like to invite discussion on this potential plan - including: >> >> - Do we think async is worth going after? Note that this is just async >> HTTP capability, not WebSockets (that would remain in Channels) >> >> - Can we do this in a reasonable timeframe? If not, is there a way >> around that? >> >> - Are the proposed modifications to how Django runs sensible? >> >> - How should we fund this? >> >> There's many more potential questions, and I really would love feedback >> on this. I'm personally pretty convinced that we can and should do this, >> but this is a decision we cannot take lightly, and I would love to hear >> what you have to say. >> >> Andrew >> > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at https://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/0b3b92b9-eee7-4909-82d6-c0138e8b5760%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
