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Without a concrete base class:>>> Animal.objects.all() SELECT ... FROM animal;With a concrete base class:>>> Animal.objects.all() SELECT ... FROM "animal" INNER JOIN "baseobject" ON ("animal"."baseobject_ptr_id" = "baseobject"."id")
What you want:>>> BaseObject.objects.all()[<Animal: Frog>, <Vegetable: Carrot>, <Mineral: Gold>, ...]What you get:>>> BaseObject.objects.all()[<BaseObject: 1>, <BaseObject: 2>, <BaseObject: 3>, ...]
So maybe you try something like:def get_some_of_everything(): qs = BaseObject.objects.all() for obj in qs: for cls in BaseObject.__subclasses__(): try: obj = cls.objects.get(baseobject_ptr=obj) break except cls.DoesNotExist: continue yield obj
“Our site worked ﬁne in development and testing, and was working wonderfully for the ﬁrst few months.“But we just added a bunch more data, and now our homepage takes 27 seconds to load.”
“But… but… everything really does need a creation date!”So give everything a creation date.
“Do the simplest thing that could possibly work.” — Simon Willison
If you must get fancy: Abstract base classes don’t suﬀer from these performance problems. Denormalize into a UI-ordered auxiliary model. Non-relational databases work particular well here (I like SOLR).
Those who do notunderstand PYTHONPATHare doomed to failure.
Fixing import madness1. Use non-project-relative imports (import app.models, not import project.app.models).2. Use relative imports (from . import x) where possible (see http://bit.ly/pep328).3. Stop using manage.py.
Delete manage.py?$ django-‐admin.py shell -‐-‐pythonpath=`pwd` -‐-‐settings=settings.local>>> import dashboard.models>>> import djdash.dashboard.modelsTraceback (most recent call last)...ImportError: No module named djdash.dashboard.models