On Fri, 2008-04-18 at 11:02 +0100, andy baxter wrote: [...] > Has anyone dealt with this problem in practice, and do people have any > thoughts about what is the best way of doing things here, from the point > of view of keeping the code simple, and also minimising the time spent > doing database lookups? (I'm guessing that looking up a User from a > Member is slightly quicker than looking up a Member from a User).
This is kind of an interesting problem and I've come across it twice recently and ended up going with different approaches each time. Firstly, to get rid of one source of confusion, there is no difference traversing from User -> a profile or vice-versa. Both require a table join at the database level. If you're splitting hairs on the difference at the Python code level, it's so minor (and so varied) that something is seriously wrong if you notice it. So that (direction) should not be a consideration at all. In both my cases, I originally tried to puzzle out what would be the "obvious, right" way, but it only became clearer after I started writing code. In one case, most of the uses of the User+Profile pair was dealing with aspects of the standard user model (auth stuff, permissions and things like that), so I mostly needed to access User. In the other case, I was mostly referring to the profile object and so the many, many models I have linking back to the "user" link to this profile: because I primarily need the extra information. I'm still not sure I could have completely puzzled this out in advance, without more or less writing the code in my head. That's kind of the cost (and benefit) of rapid development: you can happily try something out and change a little later. On the first project (where I end up pointing to User), it became clear fairly quickly that the User model was the right one. In the second case, I vacillated a fair bit and changed my mind more than once over a three or four day period. The fact that it was such a line ball also convinced me it probably wasn't that big a deal. My time budget isn't being predominantly spent on the User/Profile joins and lookups, it's going elsewhere. So it probably wouldn't have mattered much and at some point I made a conscious decision to stop worrying about that and move on. It was starting to dominate my thinking a bit too much. Regards, Malcolm -- I intend to live forever - so far so good. http://www.pointy-stick.com/blog/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
