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import contextlib
import threading
from django.db import models
from django.utils import translation
import caching.base
import multidb.pinning
import queryset_transform
from translations import transformer
from . import signals
_locals = threading.local()
_locals.skip_cache = False
@contextlib.contextmanager
def use_master():
"""Within this context, all queries go to the master."""
multidb.pinning.pin_this_thread()
try:
yield
finally:
multidb.pinning.unpin_this_thread()
@contextlib.contextmanager
def skip_cache():
"""Within this context, no queries come from cache."""
_locals.skip_cache = True
try:
yield
finally:
_locals.skip_cache = False
class TransformQuerySet(queryset_transform.TransformQuerySet):
def pop_transforms(self):
qs = self._clone()
transforms = qs._transform_fns
qs._transform_fns = []
return transforms, qs
def no_transforms(self):
return self.pop_transforms()[1]
def only_translations(self):
"""Remove all transforms except translations."""
# Add an extra select so these are cached separately.
qs = self.no_transforms().extra(select={'_only_trans': 1})
if hasattr(self.model._meta, 'translated_fields'):
qs = qs.transform(transformer.get_trans)
return qs
class RawQuerySet(models.query.RawQuerySet):
"""A RawQuerySet with __len__."""
def __init__(self, *args, **kw):
super(RawQuerySet, self).__init__(*args, **kw)
self._result_cache = None
def __iter__(self):
if self._result_cache is None:
self._result_cache = list(super(RawQuerySet, self).__iter__())
return iter(self._result_cache)
def __len__(self):
return len(list(self.__iter__()))
class CachingRawQuerySet(RawQuerySet, caching.base.CachingRawQuerySet):
"""A RawQuerySet with __len__ and caching."""
# Make TransformQuerySet one of CachingQuerySet's parents so that we can do
# transforms on objects and then get them cached.
CachingQuerySet = caching.base.CachingQuerySet
CachingQuerySet.__bases__ = (TransformQuerySet,) + CachingQuerySet.__bases__
class UncachedManagerBase(models.Manager):
def get_query_set(self):
qs = self._with_translations(TransformQuerySet(self.model))
return qs
def _with_translations(self, qs):
# Since we're attaching translations to the object, we need to stick
# the locale in the query so objects aren't shared across locales.
if hasattr(self.model._meta, 'translated_fields'):
lang = translation.get_language()
qs = qs.transform(transformer.get_trans)
qs = qs.extra(where=['"%s"="%s"' % (lang, lang)])
return qs
def transform(self, fn):
return self.all().transform(fn)
def raw(self, raw_query, params=None, *args, **kwargs):
return RawQuerySet(raw_query, self.model, params=params,
using=self._db, *args, **kwargs)
class ManagerBase(caching.base.CachingManager, UncachedManagerBase):
"""
Base for all managers in AMO.
Returns TransformQuerySets from the queryset_transform project.
If a model has translated fields, they'll be attached through a transform
function.
"""
def get_query_set(self):
qs = super(ManagerBase, self).get_query_set()
if getattr(_locals, 'skip_cache', False):
qs = qs.no_cache()
return self._with_translations(qs)
def raw(self, raw_query, params=None, *args, **kwargs):
return CachingRawQuerySet(raw_query, self.model, params=params,
using=self._db, *args, **kwargs)
class ModelBase(caching.base.CachingMixin, models.Model):
"""
Base class for AMO models to abstract some common features.
* Adds automatic created and modified fields to the model.
* Fetches all translations in one subsequent query during initialization.
"""
created = models.DateTimeField(auto_now_add=True)
modified = models.DateTimeField(auto_now=True)
objects = ManagerBase()
uncached = UncachedManagerBase()
class Meta:
abstract = True
get_latest_by = 'created'
def get_absolute_url(self, *args, **kwargs):
return self.get_url_path(*args, **kwargs)
def manual_order(qs, pks, pk_name='id'):
"""
Given a query set and a list of primary keys, return a set of objects from
the query set in that exact order.
"""
if not pks:
return []
objects = qs.filter(id__in=pks).extra(
select={'_manual': 'FIELD(%s, %s)'
% (pk_name, ','.join(map(str, pks)))},
order_by=['_manual'])
return objects
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