349 строки
10 KiB
Python
349 строки
10 KiB
Python
from collections import defaultdict
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import contextlib
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import threading
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from django.conf import settings
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from django.db import models
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from django.utils import translation
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import caching.base
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import elasticutils
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import multidb.pinning
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import queryset_transform
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from . import signals, search
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_locals = threading.local()
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_locals.skip_cache = False
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@contextlib.contextmanager
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def use_master():
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"""Within this context, all queries go to the master."""
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old = getattr(multidb.pinning._locals, 'pinned', False)
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multidb.pinning.pin_this_thread()
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try:
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yield
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finally:
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multidb.pinning._locals.pinned = old
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@contextlib.contextmanager
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def skip_cache():
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"""Within this context, no queries come from cache."""
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old = getattr(_locals, 'skip_cache', False)
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_locals.skip_cache = True
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try:
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yield
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finally:
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_locals.skip_cache = old
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# This is sadly a copy and paste of annotate to get around this
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# ticket http://code.djangoproject.com/ticket/14707
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def annotate(self, *args, **kwargs):
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for arg in args:
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if arg.default_alias in kwargs:
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raise ValueError("The %s named annotation conflicts with the "
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"default name for another annotation."
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% arg.default_alias)
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kwargs[arg.default_alias] = arg
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obj = self._clone()
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obj._setup_aggregate_query(kwargs.keys())
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# Add the aggregates to the query
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for (alias, aggregate_expr) in kwargs.items():
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obj.query.add_aggregate(aggregate_expr, self.model, alias,
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is_summary=False)
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return obj
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models.query.QuerySet.annotate = annotate
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class TransformQuerySet(queryset_transform.TransformQuerySet):
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def pop_transforms(self):
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qs = self._clone()
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transforms = qs._transform_fns
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qs._transform_fns = []
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return transforms, qs
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def no_transforms(self):
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return self.pop_transforms()[1]
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def only_translations(self):
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"""Remove all transforms except translations."""
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from translations import transformer
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# Add an extra select so these are cached separately.
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return (self.no_transforms().extra(select={'_only_trans': 1})
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.transform(transformer.get_trans))
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def transform(self, fn):
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from . import decorators
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f = decorators.skip_cache(fn)
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return super(TransformQuerySet, self).transform(f)
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class RawQuerySet(models.query.RawQuerySet):
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"""A RawQuerySet with __len__."""
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def __init__(self, *args, **kw):
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super(RawQuerySet, self).__init__(*args, **kw)
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self._result_cache = None
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def __iter__(self):
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if self._result_cache is None:
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self._result_cache = list(super(RawQuerySet, self).__iter__())
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return iter(self._result_cache)
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def __len__(self):
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return len(list(self.__iter__()))
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class CachingRawQuerySet(RawQuerySet, caching.base.CachingRawQuerySet):
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"""A RawQuerySet with __len__ and caching."""
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# Make TransformQuerySet one of CachingQuerySet's parents so that we can do
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# transforms on objects and then get them cached.
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CachingQuerySet = caching.base.CachingQuerySet
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CachingQuerySet.__bases__ = (TransformQuerySet,) + CachingQuerySet.__bases__
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class UncachedManagerBase(models.Manager):
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def get_query_set(self):
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qs = self._with_translations(TransformQuerySet(self.model))
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return qs
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def _with_translations(self, qs):
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from translations import transformer
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# Since we're attaching translations to the object, we need to stick
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# the locale in the query so objects aren't shared across locales.
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if hasattr(self.model._meta, 'translated_fields'):
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lang = translation.get_language()
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qs = qs.transform(transformer.get_trans)
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qs = qs.extra(where=['"%s"="%s"' % (lang, lang)])
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return qs
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def transform(self, fn):
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return self.all().transform(fn)
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def raw(self, raw_query, params=None, *args, **kwargs):
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return RawQuerySet(raw_query, self.model, params=params,
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using=self._db, *args, **kwargs)
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class ManagerBase(caching.base.CachingManager, UncachedManagerBase):
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"""
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Base for all managers in AMO.
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Returns TransformQuerySets from the queryset_transform project.
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If a model has translated fields, they'll be attached through a transform
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function.
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"""
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def get_query_set(self):
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qs = super(ManagerBase, self).get_query_set()
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if getattr(_locals, 'skip_cache', False):
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qs = qs.no_cache()
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return self._with_translations(qs)
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def raw(self, raw_query, params=None, *args, **kwargs):
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return CachingRawQuerySet(raw_query, self.model, params=params,
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using=self._db, *args, **kwargs)
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class _NoChangeInstance(object):
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"""A proxy for object instances to make safe operations within an
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OnChangeMixin.on_change() callback.
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"""
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def __init__(self, instance):
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self.__instance = instance
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def __repr__(self):
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return u'<%s for %r>' % (self.__class__.__name__, self.__instance)
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def __getattr__(self, attr):
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return getattr(self.__instance, attr)
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def __setattr__(self, attr, val):
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if attr.endswith('__instance'):
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# _NoChangeInstance__instance
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self.__dict__[attr] = val
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else:
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setattr(self.__instance, attr, val)
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def save(self, *args, **kw):
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kw['_signal'] = False
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return self.__instance.save(*args, **kw)
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def update(self, *args, **kw):
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kw['_signal'] = False
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return self.__instance.update(*args, **kw)
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_on_change_callbacks = defaultdict(list)
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# @TODO(Kumar) liberate: move OnChangeMixin Model mixin to nuggets
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class OnChangeMixin(object):
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"""Mixin for a Model that allows you to observe attribute changes.
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Register change observers with::
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class YourModel(amo.models.OnChangeMixin,
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amo.models.ModelBase):
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# ...
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pass
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YourModel.on_change(callback)
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"""
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def __init__(self, *args, **kw):
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super(OnChangeMixin, self).__init__(*args, **kw)
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self._initial_attr = dict(self.__dict__)
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@classmethod
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def on_change(cls, callback):
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"""Register a function to call on save or update to respond to changes.
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For example::
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def watch_status(old_attr={}, new_attr={},
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instance=None, sender=None, **kw):
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if old_attr.get('status') != new_attr.get('status'):
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# ...
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new_instance.save(_signal=False)
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TheModel.on_change(watch_status)
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.. note::
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Any call to instance.save() or instance.update() within a callback
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will not trigger any change handlers.
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"""
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_on_change_callbacks[cls].append(callback)
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return callback
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def _send_changes(self, old_attr, new_attr_kw):
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new_attr = old_attr.copy()
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new_attr.update(new_attr_kw)
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for cb in _on_change_callbacks[self.__class__]:
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cb(old_attr=old_attr, new_attr=new_attr,
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instance=_NoChangeInstance(self), sender=self.__class__)
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def save(self, *args, **kw):
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"""
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Save changes to the model instance.
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If _signal=False is in `kw` the on_change() callbacks won't be called.
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"""
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signal = kw.pop('_signal', True)
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result = super(OnChangeMixin, self).save(*args, **kw)
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if signal:
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self._send_changes(self._initial_attr, dict(self.__dict__))
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return result
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def update(self, **kw):
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"""
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Shortcut for doing an UPDATE on this object.
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If _signal=False is in ``kw`` the post_save signal won't be sent.
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"""
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signal = kw.pop('_signal', True)
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old_attr = dict(self.__dict__)
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result = super(OnChangeMixin, self).update(**kw)
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if signal:
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self._send_changes(old_attr, kw)
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return result
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class SearchMixin(object):
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@classmethod
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def index(cls, document, id=None, bulk=False, force_insert=False):
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"""Wrapper around pyes.ES.index."""
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elasticutils.get_es().index(
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document, index=settings.ES_INDEX, doc_type=cls._meta.app_label,
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id=id, bulk=bulk, force_insert=force_insert)
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@classmethod
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def unindex(cls, id):
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elasticutils.get_es().delete(settings.ES_INDEX,
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cls._meta.app_label, id)
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@classmethod
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def search(cls):
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return search.ES(cls)
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class ModelBase(SearchMixin, caching.base.CachingMixin, models.Model):
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"""
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Base class for AMO models to abstract some common features.
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* Adds automatic created and modified fields to the model.
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* Fetches all translations in one subsequent query during initialization.
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"""
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created = models.DateTimeField(auto_now_add=True)
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modified = models.DateTimeField(auto_now=True)
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objects = ManagerBase()
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uncached = UncachedManagerBase()
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class Meta:
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abstract = True
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get_latest_by = 'created'
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def get_absolute_url(self, *args, **kwargs):
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return self.get_url_path(*args, **kwargs)
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def update(self, **kw):
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"""
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Shortcut for doing an UPDATE on this object.
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If _signal=False is in ``kw`` the post_save signal won't be sent.
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"""
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signal = kw.pop('_signal', True)
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cls = self.__class__
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for k, v in kw.items():
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setattr(self, k, v)
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if signal:
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# Detect any attribute changes during pre_save and add those to the
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# update kwargs.
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attrs = dict(self.__dict__)
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models.signals.pre_save.send(sender=cls, instance=self)
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for k, v in self.__dict__.items():
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if attrs[k] != v:
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kw[k] = v
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setattr(self, k, v)
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cls.objects.filter(pk=self.pk).update(**kw)
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if signal:
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models.signals.post_save.send(sender=cls, instance=self,
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created=False)
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def manual_order(qs, pks, pk_name='id'):
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"""
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Given a query set and a list of primary keys, return a set of objects from
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the query set in that exact order.
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"""
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if not pks:
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return []
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objects = qs.filter(id__in=pks).extra(
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select={'_manual': 'FIELD(%s, %s)'
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% (pk_name, ','.join(map(str, pks)))},
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order_by=['_manual'])
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return objects
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