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Code Issues 32 Releases Wiki Activity

Fixed #26226 -- Made related managers honor the queryset used for prefetching their results.

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Thanks Loïc for the suggested improvements and Tim for the review.
This commit is contained in:
Simon Charette
2016-02-18 22:37:11 -05:00
parent 5d240b070d
commit c92123cc1d
6 changed files with 133 additions and 22 deletions
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11
django/contrib/contenttypes/fields.py
View File

@@ -521,12 +521,19 @@ def create_generic_related_manager(superclass, rel):
def __str__(self):
return repr(self)
def _apply_rel_filters(self, queryset):
"""
Filter the queryset for the instance this manager is bound to.
"""
db = self._db or router.db_for_read(self.model, instance=self.instance)
return queryset.using(db).filter(**self.core_filters)
def get_queryset(self):
try:
return self.instance._prefetched_objects_cache[self.prefetch_cache_name]
except (AttributeError, KeyError):
db = self._db or router.db_for_read(self.model, instance=self.instance)
return super(GenericRelatedObjectManager, self).get_queryset().using(db).filter(**self.core_filters)
queryset = super(GenericRelatedObjectManager, self).get_queryset()
return self._apply_rel_filters(queryset)
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:

48
django/db/models/fields/related_descriptors.py
View File

@@ -502,23 +502,29 @@ def create_reverse_many_to_one_manager(superclass, rel):
return manager_class(self.instance)
do_not_call_in_templates = True
def _apply_rel_filters(self, queryset):
"""
Filter the queryset for the instance this manager is bound to.
"""
db = self._db or router.db_for_read(self.model, instance=self.instance)
empty_strings_as_null = connections[db].features.interprets_empty_strings_as_nulls
queryset._add_hints(instance=self.instance)
if self._db:
queryset = queryset.using(self._db)
queryset = queryset.filter(**self.core_filters)
for field in self.field.foreign_related_fields:
val = getattr(self.instance, field.attname)
if val is None or (val == '' and empty_strings_as_null):
return queryset.none()
queryset._known_related_objects = {self.field: {self.instance.pk: self.instance}}
return queryset
def get_queryset(self):
try:
return self.instance._prefetched_objects_cache[self.field.related_query_name()]
except (AttributeError, KeyError):
db = self._db or router.db_for_read(self.model, instance=self.instance)
empty_strings_as_null = connections[db].features.interprets_empty_strings_as_nulls
qs = super(RelatedManager, self).get_queryset()
qs._add_hints(instance=self.instance)
if self._db:
qs = qs.using(self._db)
qs = qs.filter(**self.core_filters)
for field in self.field.foreign_related_fields:
val = getattr(self.instance, field.attname)
if val is None or (val == '' and empty_strings_as_null):
return qs.none()
qs._known_related_objects = {self.field: {self.instance.pk: self.instance}}
return qs
queryset = super(RelatedManager, self).get_queryset()
return self._apply_rel_filters(queryset)
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:
@@ -776,15 +782,21 @@ def create_forward_many_to_many_manager(superclass, rel, reverse):
filters |= symmetrical_filters
return filters
def _apply_rel_filters(self, queryset):
"""
Filter the queryset for the instance this manager is bound to.
"""
queryset._add_hints(instance=self.instance)
if self._db:
queryset = queryset.using(self._db)
return queryset._next_is_sticky().filter(**self.core_filters)
def get_queryset(self):
try:
return self.instance._prefetched_objects_cache[self.prefetch_cache_name]
except (AttributeError, KeyError):
qs = super(ManyRelatedManager, self).get_queryset()
qs._add_hints(instance=self.instance)
if self._db:
qs = qs.using(self._db)
return qs._next_is_sticky().filter(**self.core_filters)
queryset = super(ManyRelatedManager, self).get_queryset()
return self._apply_rel_filters(queryset)
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:

23
django/db/models/query.py
View File

@@ -23,6 +23,7 @@ from django.db.models.query_utils import (
)
from django.db.models.sql.constants import CURSOR
from django.utils import six, timezone
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.functional import partition
from django.utils.version import get_version
@@ -1608,6 +1609,9 @@ def prefetch_one_level(instances, prefetcher, lookup, level):
msg = 'to_attr={} conflicts with a field on the {} model.'
raise ValueError(msg.format(to_attr, model.__name__))
# Whether or not we're prefetching the last part of the lookup.
leaf = len(lookup.prefetch_through.split(LOOKUP_SEP)) - 1 == level
for obj in instances:
instance_attr_val = instance_attr(obj)
vals = rel_obj_cache.get(instance_attr_val, [])
@@ -1621,8 +1625,23 @@ def prefetch_one_level(instances, prefetcher, lookup, level):
setattr(obj, to_attr, vals)
obj._prefetched_objects_cache[cache_name] = vals
else:
# Cache in the QuerySet.all().
qs = getattr(obj, to_attr).all()
manager = getattr(obj, to_attr)
if leaf and lookup.queryset is not None:
try:
apply_rel_filter = manager._apply_rel_filters
except AttributeError:
warnings.warn(
"The `%s.%s` class must implement a `_apply_rel_filters()` "
"method that accepts a `QuerySet` as its single "
"argument and returns an appropriately filtered version "
"of it." % (manager.__class__.__module__, manager.__class__.__name__),
RemovedInDjango20Warning,
)
qs = manager.get_queryset()
else:
qs = apply_rel_filter(lookup.queryset)
else:
qs = manager.get_queryset()
qs._result_cache = vals
# We don't want the individual qs doing prefetch_related now,
# since we have merged this into the current work.