I ran across this problem today – do please leave a comment if you know of a better way to solve it than what follows.

You have two Django models, one of which inherits from the other, e.g.:

class Order(models.Model):
    # some fields

class DiningOrder(Order):
    # some more fields

So, how do I write a query (using the Django ORM) which returns all the Orders which are not DiningOrders?

Apparently, this does the trick:

>>> Order.objects.all().count()
762L
>>> DiningOrder.objects.all().count()
93L
>>> Order.objects.exclude(id__in=[d.id for d in DiningOrder.objects.all()]).count()
669L

Add in category filtering and a web interface – such as it is – and you get Bogroll, which I’ve just released under the GPL. You can grab the 0.1 release, check out the code from subversion, and have a nosey at my installation.

Incidentally, if anyone can think of a better name for it, do get in touch.

In other news, I appear to have reached the end of another Oxford term with my sanity intact. The first six weeks were great, it just got a bit wearing for the last two. Some of the non-academic stuff, sadly, is going to have to take a back seat after Christmas, but ah well.

In other news, I blew £160 on new technology for my desk this week: specifically, a new 4GB USB pendrive to replace my ailing 256mb one, a 250GB external hard disk for my backups, and best of all, a 19 inch TFT monitor to act as a second screen for my laptop.

All of the above were very reasonably priced over at Dabs, and the £100 inc delivery cost of the monitor in particular came as a very pleasant surprise.

This is the first time I’ve given multiple monitors a serious go under Linux (specifically Kubuntu), and KDE certainly puts Windows (at least up to and including XP) into the shade here: a taskbar on each monitor? Yes, it can do that. Separate background images per monitor (without silly hacks involving stitching image files together)? Yes. Only show the buttons for the windows on this monitor on this monitor’s taskbar? Certainly, sir.

It’s only been two days, but I’m already wondering how I ever managed without a secondary screen. It certainly made finishing the new theme for this site a lot easier.

The first one, as the regular readers amongst you will notice, was for this site (apologies to those of you reading this on Planet CompSoc, you’ll have to click through to see what I’m on about). I’ve gone for a minimalist black-and-white look. I’m not entirely happy with it, but I’ll keep tweaking…

The second, still very much in progress, is for the Magdalen College JCR site, which I’m giving a comprehensive makeover this summer. Feel free to leave a comment on either – constructive criticism is always welcome.

Update

Apologies to anyone who visited this site at about 20.40 BST on 27/06/2007 and wondered what the heck had happened to the new theme this post mentioned. Suffice to say that the correct way to fiddle with WordPress is to start in the backend manager, not to do random find-and-replaces across the underlying code. Don’t try and rename the directory the current theme lives in, either.