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"""
This module offers functions and abstract base classes that can be used to
store translated models. There isn't much magic going on here.
Usage example::
class News(models.Model, TranslatedObjectMixin):
active = models.BooleanField(default=False)
created = models.DateTimeField(default=datetime.now)
class NewsTranslation(Translation(News)):
title = models.CharField(max_length=200)
body = models.TextField()
Print the titles of all news entries either in the current language (if available)
or in any other language::
for news in News.objects.all():
print news.translation.title
Print all the titles of all news entries which have an english translation::
from django.utils import translation
translation.activate('en')
for news in News.objects.filter(translations__language_code='en'):
print news.translation.title
"""
from django.conf import settings
from django.contrib import admin
from django.core.cache import cache
from django.core.exceptions import ObjectDoesNotExist
from django.db import models
from django.db.models import Q
from django.utils import translation
from django.utils.translation import ugettext_lazy as _
def short_language_code(code=None):
"""
Extract the short language code from its argument (or return the default language code).
>>> from django.conf import settings
>>> short_language_code('de')
'de'
>>> short_language_code('de-at')
'de'
>>> short_language_code() == short_language_code(settings.LANGUAGE_CODE)
True
"""
if code is None:
code = translation.get_language()
pos = code.find('-')
if pos > -1:
return code[:pos]
return code
def is_primary_language(language=None):
"""
Returns true if current or passed language is the primary language for this site.
(The primary language is defined as the first language in settings.LANGUAGES.)
"""
if not language:
language = translation.get_language()
return language == settings.LANGUAGES[0][0]
class TranslatedObjectManager(models.Manager):
"""
This manager offers convenience methods.
"""
def only_language(self, language=short_language_code):
"""
Only return objects which have a translation into the given language.
Uses the currently active language by default.
"""
return self.filter(translations__language_code=language)
class TranslatedObjectMixin(object):
"""
Mixin with helper methods.
"""
def _get_translation_object(self, queryset, language_code):
try:
return queryset.filter(
Q(language_code=language_code)
| Q(language_code=short_language_code(language_code))
).order_by('-language_code')[0]
except IndexError:
try:
return queryset.filter(
Q(language_code__istartswith=settings.LANGUAGE_CODE)
| Q(language_code__istartswith=short_language_code(settings.LANGUAGE_CODE))
).order_by('-language_code')[0]
except IndexError:
try:
return queryset.all()[0]
except IndexError:
raise queryset.model.DoesNotExist
def get_translation_cache_key(self, language_code=None):
"""Return the cache key used to cache this object's translations so we can purge on-demand"""
if not language_code:
language_code = translation.get_language()
return '-'.join(['%s' % s for s in
self._meta.db_table,
self.id,
language_code,
])
def get_translation(self, language_code=None):
if not language_code:
language_code = translation.get_language()
key = self.get_translation_cache_key(language_code)
trans = cache.get(key)
if trans is None:
trans = self._get_translation_object(self.translations.all(), language_code)
cache.set(key, trans)
# Assign self to prevent additional database queries
trans.parent = self
return trans
translation = property(get_translation)
@property
def available_translations(self):
return self.translations.values_list('language_code', flat=True)
def __unicode__(self):
try:
translation = self.translation
except ObjectDoesNotExist:
return self.__class__.__name__
if translation:
return unicode(translation)
return self.__class__.__name__
def get_absolute_url(self):
return self.translation.get_absolute_url()
def purge_translation_cache(self):
cache.delete(self.get_translation_cache_key())
for lang in self.available_translations:
cache.delete(self.get_translation_cache_key(lang))
def Translation(model):
"""
Return a class which can be used as inheritance base for translation models
"""
class Inner(models.Model):
parent = models.ForeignKey(model, related_name='translations')
language_code = models.CharField(_('language'), max_length=10,
choices=settings.LANGUAGES, default=settings.LANGUAGES[0][0],
editable=len(settings.LANGUAGES) > 1)
class Meta:
abstract = True
def short_language_code(self):
return short_language_code(self.language_code)
def save(self, *args, **kwargs):
super(Inner, self).save(*args, **kwargs)
self.parent.purge_translation_cache()
return Inner
def admin_translationinline(model, inline_class=admin.StackedInline, **kwargs):
"""
Returns a new inline type suitable for the Django administration::
from django.contrib import admin
from myapp.models import News, NewsTranslation
admin.site.register(News,
inlines=[
admin_translationinline(NewsTranslation),
],
)
"""
kwargs['max_num'] = len(settings.LANGUAGES)
kwargs['model'] = model
return type(model.__class__.__name__ + 'Inline', (inline_class,), kwargs)
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