#django

other than that, no idea

Hi everyone, I'm using a plug-in named "django-countries" , anyone familiar with it? I'm having problem with sorting the objects by their name, it always orders them by their country code

+Markush: thanks

but not sure if partials work with migrations

Haven't tried that one

Country.objects.order_by('country__name') is not working because it's actually a "CountryField()" rather than a foreignkey

Does Country really have a member country? Or just a member name?

fesener_: I don't see a way to order on database level

jessamynsmith, sorry i didnt understand the question

MarkusH, thanks for checking it out anyway :)

something like "return unicode(self.country.name)" works perfectly but i cant do country__name for ordering

You might want to watch out for SmileyChris in here ;)

yea I was hoping to find him here :)

fesener_: django-countries doesn't save the name in the DB

it is hard coded in python code

ah thats why I cant get __name

i wish there was a way

yea :( i guess i cant order them by name, thank you

fesener_: well, there is a way: https://gist.github.com/cpjolicoeur/3590737#com...

but depending on how may objects you need to sort, I'd just do that on python level

it will be like 30-40 countries at most

sorted(some_list, key=operator.attrgetter('someattr'))

can you help me adapt that to my Country.objects.order_by() line?

countries = Country.objects.all() ; sorted(countries, key=operator.attrgetter('name')) ?

let me try

it says operator is not defined

import operator

'Country' object has no attribute 'name'

what is "Country"?

countries = Country.objects.all()

Let's see your Country model, please

fwiw: https://dpaste.de/YWFy

oops: https://dpaste.de/vJyW

That's better

MarkusH, https://dpaste.de/oH39

i guess this is what you are asking?

Is "for temperature in self.temperature_set.filter(date__gte=start).filter(date__lte=end):" more efficient than .all() and an if afterwards?

fesener_: ok, make it attrgetter('country.name')

autrilla__: depends

MarkusH, making it "countries = sorted(countries, key=operator.attrgetter('country.name'))" made it work! thank you so much

MarkusH, mind elaborating?>

you are awesome

fesener_: thanks ^^, you're welcome

autrilla__: no :-P

No you don't mind or no you won't elaborate? :p

autrilla__: well, it probably depends on the amount of data you are querying

Well not much now, but i production I can expect every user to have thousands of the temperature model

but I guess the .filter() thing is mostly faster ;)

in* production

The .filter runs on the database right?

yes

Which is probably faster as it's probably C instead of python

so you don't have to construct billions of objects

yes

Great, thanks

also, because it uses the database indexes which are pre-sorted

so make sure you put an index on the name attribute if you're going to be sorting on it

Can I show related stuff to an object on the admin?

Can you do something like this? https://gist.github.com/autrilla/b3f9ce75f9cba6...

I get __str__ returned non-string (type NoneType)

Probably because Zone.__str__ doesn't always return a string.

Incidentally, you may be jumping into using multi-table model inheritance prematurely.

that's how I'd do it in java

Well, these classes map to database tables, they're not like ordinary classes.

So you should be thinking about the DB structure more than what makes sense in Java.

Well, so the Zone class shouldn't me a model?

autrilla__: mattmcc: I'd go with something like https://dpaste.de/Nt2Q

Depends on what other types of zones you have in mind, and how far they nest.

SQL DBs _suck_ at nesting if you don't use the right structure.

mattmcc, that's basically it... the original plan was one Farm with as many subzones as you want, but just one depth level

Well, not one Farm, many farms each with many Subzones

Yeah, then you want models to relate to each other, don't need inheritance to do that.

You may also want __unicode__, rather than __str__.

You can use an abstract model for common fields

schinckel: no

mattmcc, but then Devices can be on either Farms or Subzones

This is one of those fundamental disconnects between OOP and SQL.

you want python 3

schinckel: use __str__ and @python_2_unicode_compatible

That's why I had a superclass, so Devices could have a Zone

Wonder what I'm doing with my alleged 2-and-3 compatible apps then... ;)

MarkusH, so with your suggestion, everything is a Zone, and if the farm attribute is not set, it's a farm, and if it is set, it's a subzone?

autrilla__: yes

I could probably name it parent instead of farm and let the user decide how much depth he wants

autrilla__: if you use "my" pattern, you don't want more than 1 level of nesting

2 at most if you have a medium sized database

why not/

?*

this pattern sucks for relational databases

When you want to nest more, you want a tree pattern like materialized-path or nested-set.

Which add extra fields to your models that allow for tree traversal without having to use recursion.

or, if you want to have arbirary nesting, look at django-treebeard or others (never used that one myself)

Yeah, treebeard provides models for both patterns.

Well, in my case each query wouldn't have to handle more than 500 rows at a time, I think all servers can handle that

Famous last words.. :)

haha, yes

anyways, I gotta go. Bed time

And for those of you using Uber instead of taxi companies: change your password: http://motherboard.vice.com/read/stolen-uber-cu...

Disconnected, the last message I sent was <autrilla__> Well, in my case each query wouldn't have to handle more than 500 rows at a time, I think all servers can handle that

hi

i have a db-related django question

I do understand it's slower but, only if you do queries that require recursion

, but*

how would I do something like add a unique constraint to a PAIR of fields? i.e. I have a "portion" class that has properties for size(0-9) and unit (oz/g/kg) with a foreign key to a food item

i would not want it to be possible to create duplicate portions for the same food

masterrex: unique_together

<3

=)

that's exactly what i'm after

tusind tak

ok this is weird

hum, another dumb question... let's say I have a choices tuple that I want to utilize for multiple classes... apparently I can't just define it at the top of the models.py module

TypeError: 'tuple' object is not callable

Sure you can.

masterrex: welcome to #django please dpaste code etc.

doismellburning: I've been a nuisance here for a while :P