#django

Howdy, I'm trying to construct a dynamic query that, given a list of number ranges, will find all instances of a ModelObject myNumber where an integer value is between any of those ranges. Do I create some filter object, then use the |= operator for the lower and upper number in my range to construct my filter?

EagleOne: For now, encode/decode. For later, explore utf8 and url handling in Django. If you've spent time on this then the cost of typing 20 more letters is trivial.

yep..

Scottyob: You can use Q objects with a logical OR, and add them together iteratively. So break the ranges provided into a list, for example, then do something like { for i in ranges:; query |= Q(i); }.

Scottyob: The whole idea is that you can tack more Q objects onto each other using the |= operator, and then feed the result to a filter() method.

zxq9: what does the |= operator do? Creates the OR?

Scottyob: That will generate SQL similar to "SELECT * FROM foo WHERE (a > x1 AND a < y1) OR (b > x2 AND b y2)" (it might even generate a range function, but regardless, you get the idea)

|= is bitwise OR

er, bitwise OR-equal.

(not that there's a non-bitwise OR-equal)

Scottyob: The |= operator is the old C bitwise "OR equals" but in Python it seems to work in a more general sense.

oh right. Good stuff. So just build my q = model.objects.filter(number__gte=rangeLower, number__lte=rangeUpper); q |= model.objects.filter(number__gte=rangeLower2, number__lte=rangeUpper2)....

sorry, that was a question

Hi! Where am I supposed to place my templates folder with Django 1.4? Does it make any sense to have a general/main templates folder at the root of my django folder? Or should I try and rely only on app-specific templates?

does anyone know how to mask django form field inputs? I want to format them as currenecy, but submit them as Decimals still.

yeah, that works perfect. Thanks zxq9, eternicode :)

Very interesting. Bit the bullet and rewrote using (proper) aggregation and not only does it work, but it's much faster. Heh. I'd call that a win.

notanumber: The reason for the slowness was the same reason it didn't display anything. Each iteration was hitting the database an additional time (which can be enormous numbers of hits, like tens of thousands on large results of non-trivial data processing), *and* without a specific fetch for a value nothing would have been evaluated in the first place.

Oh yeah, I'm fully aware of that. My philosophy is to to write it once, then profile and fix the slow bits. No sense spending time on something that's only run once every other month. In this case though, it was clearly broken. I would have had to fix it eventually anyway as this routine was seeing a lot of usage.

To much to do to little time.

hi evryone

*everyone

this might sound like a stupid question, but is it possible to create an empty query which doesn't return anything (so I can then later use |= with it?)

http://dpaste.org/f7scs/ <-- Im trying to follow along with https://docs.djangoproject.com/en/1.4/howto/cus... but I get poll_extras' is not a valid tag library -- I have the file in the correct place and it is registered correctly I think. What else could I be doing wrong?

bigkevmcd: hi

Scottyob: The closest thing would maybe be an empty Q object that you could |= to. But while query objects themselves behave similar to lists, they are not actually lists, so appending them doesn't work the way you're thinking.

Scottyob: If you extract query results as a list of models, however, you can then .append() or .extend() the list and do whatever you want.

zxq9: this is more or less what I'm trying to do

zwq9: guess what. This was a bug of Django 1.5 !

zxq9: on Django 1.4 and 1.5a1 it works just fine!

is there an option in a model field to set invalid data (which it will never save) or do I just put validation in save() or something like that?

oh, am I supposed to use Model.clean()?

cellofellow: https://docs.djangoproject.com/en/1.4/ref/model...