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Fixed #22341 -- Split django.db.models.fields.related.

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At 2800 lines it was the largest module in the django package. This
commit brings it down to a more manageable 1620 lines.

Very small changes were performed to uniformize import style.
This commit is contained in:
Aymeric Augustin
2015-09-19 14:13:56 +02:00
parent 1335aa2fb9
commit 005c9fc45f
3 changed files with 1213 additions and 1191 deletions
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django/db/models/fields/related.py
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django/db/models/fields/related_descriptors.py Normal file
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from __future__ import unicode_literals
from operator import attrgetter
from django.db import connections, router, transaction
from django.db.models import Q, signals
from django.db.models.query import QuerySet
from django.utils.functional import cached_property
class ReverseSingleRelatedObjectDescriptor(object):
"""
Accessor to the related object on the forward side of a many-to-one or
one-to-one relation.
In the example::
class Choice(Model):
poll = ForeignKey(Place, related_name='choices')
`choice.poll` is a ReverseSingleRelatedObjectDescriptor instance.
"""
def __init__(self, field_with_rel):
self.field = field_with_rel
self.cache_name = self.field.get_cache_name()
@cached_property
def RelatedObjectDoesNotExist(self):
# The exception can't be created at initialization time since the
# related model might not be resolved yet; `rel.model` might still be
# a string model reference.
return type(
str('RelatedObjectDoesNotExist'),
(self.field.remote_field.model.DoesNotExist, AttributeError),
{}
)
def is_cached(self, instance):
return hasattr(instance, self.cache_name)
def get_queryset(self, **hints):
manager = self.field.remote_field.model._default_manager
# If the related manager indicates that it should be used for
# related fields, respect that.
if not getattr(manager, 'use_for_related_fields', False):
manager = self.field.remote_field.model._base_manager
return manager.db_manager(hints=hints).all()
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:
queryset = self.get_queryset()
queryset._add_hints(instance=instances[0])
rel_obj_attr = self.field.get_foreign_related_value
instance_attr = self.field.get_local_related_value
instances_dict = {instance_attr(inst): inst for inst in instances}
related_field = self.field.foreign_related_fields[0]
# FIXME: This will need to be revisited when we introduce support for
# composite fields. In the meantime we take this practical approach to
# solve a regression on 1.6 when the reverse manager in hidden
# (related_name ends with a '+'). Refs #21410.
# The check for len(...) == 1 is a special case that allows the query
# to be join-less and smaller. Refs #21760.
if self.field.remote_field.is_hidden() or len(self.field.foreign_related_fields) == 1:
query = {'%s__in' % related_field.name: set(instance_attr(inst)[0] for inst in instances)}
else:
query = {'%s__in' % self.field.related_query_name(): instances}
queryset = queryset.filter(**query)
# Since we're going to assign directly in the cache,
# we must manage the reverse relation cache manually.
if not self.field.remote_field.multiple:
rel_obj_cache_name = self.field.remote_field.get_cache_name()
for rel_obj in queryset:
instance = instances_dict[rel_obj_attr(rel_obj)]
setattr(rel_obj, rel_obj_cache_name, instance)
return queryset, rel_obj_attr, instance_attr, True, self.cache_name
def __get__(self, instance, instance_type=None):
if instance is None:
return self
try:
rel_obj = getattr(instance, self.cache_name)
except AttributeError:
val = self.field.get_local_related_value(instance)
if None in val:
rel_obj = None
else:
qs = self.get_queryset(instance=instance)
qs = qs.filter(**self.field.get_reverse_related_filter(instance))
# Assuming the database enforces foreign keys, this won't fail.
rel_obj = qs.get()
if not self.field.remote_field.multiple:
setattr(rel_obj, self.field.remote_field.get_cache_name(), instance)
setattr(instance, self.cache_name, rel_obj)
if rel_obj is None and not self.field.null:
raise self.RelatedObjectDoesNotExist(
"%s has no %s." % (self.field.model.__name__, self.field.name)
)
else:
return rel_obj
def __set__(self, instance, value):
# If null=True, we can assign null here, but otherwise the value needs
# to be an instance of the related class.
if value is None and self.field.null is False:
raise ValueError(
'Cannot assign None: "%s.%s" does not allow null values.' %
(instance._meta.object_name, self.field.name)
)
elif value is not None and not isinstance(value, self.field.remote_field.model):
raise ValueError(
'Cannot assign "%r": "%s.%s" must be a "%s" instance.' % (
value,
instance._meta.object_name,
self.field.name,
self.field.remote_field.model._meta.object_name,
)
)
elif value is not None:
if instance._state.db is None:
instance._state.db = router.db_for_write(instance.__class__, instance=value)
elif value._state.db is None:
value._state.db = router.db_for_write(value.__class__, instance=instance)
elif value._state.db is not None and instance._state.db is not None:
if not router.allow_relation(value, instance):
raise ValueError('Cannot assign "%r": the current database router prevents this relation.' % value)
# If we're setting the value of a OneToOneField to None, we need to clear
# out the cache on any old related object. Otherwise, deleting the
# previously-related object will also cause this object to be deleted,
# which is wrong.
if value is None:
# Look up the previously-related object, which may still be available
# since we've not yet cleared out the related field.
# Use the cache directly, instead of the accessor; if we haven't
# populated the cache, then we don't care - we're only accessing
# the object to invalidate the accessor cache, so there's no
# need to populate the cache just to expire it again.
related = getattr(instance, self.cache_name, None)
# If we've got an old related object, we need to clear out its
# cache. This cache also might not exist if the related object
# hasn't been accessed yet.
if related is not None:
setattr(related, self.field.remote_field.get_cache_name(), None)
for lh_field, rh_field in self.field.related_fields:
setattr(instance, lh_field.attname, None)
# Set the values of the related field.
else:
for lh_field, rh_field in self.field.related_fields:
setattr(instance, lh_field.attname, getattr(value, rh_field.attname))
# Since we already know what the related object is, seed the related
# object caches now, too. This avoids another db hit if you get the
# object you just set.
setattr(instance, self.cache_name, value)
if value is not None and not self.field.remote_field.multiple:
setattr(value, self.field.remote_field.get_cache_name(), instance)
class SingleRelatedObjectDescriptor(object):
"""
Accessor to the related object on the reverse side of a one-to-one
relation.
In the example::
class Restaurant(Model):
place = OneToOneField(Place, related_name='restaurant')
``place.restaurant`` is a ``SingleRelatedObjectDescriptor`` instance.
"""
def __init__(self, related):
self.related = related
self.cache_name = related.get_cache_name()
@cached_property
def RelatedObjectDoesNotExist(self):
# The exception isn't created at initialization time for the sake of
# consistency with `ReverseSingleRelatedObjectDescriptor`.
return type(
str('RelatedObjectDoesNotExist'),
(self.related.related_model.DoesNotExist, AttributeError),
{}
)
def is_cached(self, instance):
return hasattr(instance, self.cache_name)
def get_queryset(self, **hints):
manager = self.related.related_model._default_manager
# If the related manager indicates that it should be used for
# related fields, respect that.
if not getattr(manager, 'use_for_related_fields', False):
manager = self.related.related_model._base_manager
return manager.db_manager(hints=hints).all()
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:
queryset = self.get_queryset()
queryset._add_hints(instance=instances[0])
rel_obj_attr = attrgetter(self.related.field.attname)
instance_attr = lambda obj: obj._get_pk_val()
instances_dict = {instance_attr(inst): inst for inst in instances}
query = {'%s__in' % self.related.field.name: instances}
queryset = queryset.filter(**query)
# Since we're going to assign directly in the cache,
# we must manage the reverse relation cache manually.
rel_obj_cache_name = self.related.field.get_cache_name()
for rel_obj in queryset:
instance = instances_dict[rel_obj_attr(rel_obj)]
setattr(rel_obj, rel_obj_cache_name, instance)
return queryset, rel_obj_attr, instance_attr, True, self.cache_name
def __get__(self, instance, instance_type=None):
if instance is None:
return self
try:
rel_obj = getattr(instance, self.cache_name)
except AttributeError:
related_pk = instance._get_pk_val()
if related_pk is None:
rel_obj = None
else:
filter_args = self.related.field.get_forward_related_filter(instance)
try:
rel_obj = self.get_queryset(instance=instance).get(**filter_args)
except self.related.related_model.DoesNotExist:
rel_obj = None
else:
setattr(rel_obj, self.related.field.get_cache_name(), instance)
setattr(instance, self.cache_name, rel_obj)
if rel_obj is None:
raise self.RelatedObjectDoesNotExist(
"%s has no %s." % (
instance.__class__.__name__,
self.related.get_accessor_name()
)
)
else:
return rel_obj
def __set__(self, instance, value):
# The similarity of the code below to the code in
# ReverseSingleRelatedObjectDescriptor is annoying, but there's a bunch
# of small differences that would make a common base class convoluted.
# If null=True, we can assign null here, but otherwise the value needs
# to be an instance of the related class.
if value is None and self.related.field.null is False:
raise ValueError(
'Cannot assign None: "%s.%s" does not allow null values.' % (
instance._meta.object_name,
self.related.get_accessor_name(),
)
)
elif value is not None and not isinstance(value, self.related.related_model):
raise ValueError(
'Cannot assign "%r": "%s.%s" must be a "%s" instance.' % (
value,
instance._meta.object_name,
self.related.get_accessor_name(),
self.related.related_model._meta.object_name,
)
)
elif value is not None:
if instance._state.db is None:
instance._state.db = router.db_for_write(instance.__class__, instance=value)
elif value._state.db is None:
value._state.db = router.db_for_write(value.__class__, instance=instance)
elif value._state.db is not None and instance._state.db is not None:
if not router.allow_relation(value, instance):
raise ValueError('Cannot assign "%r": the current database router prevents this relation.' % value)
related_pk = tuple(getattr(instance, field.attname) for field in self.related.field.foreign_related_fields)
# Set the value of the related field to the value of the related object's related field
for index, field in enumerate(self.related.field.local_related_fields):
setattr(value, field.attname, related_pk[index])
# Since we already know what the related object is, seed the related
# object caches now, too. This avoids another db hit if you get the
# object you just set.
setattr(instance, self.cache_name, value)
setattr(value, self.related.field.get_cache_name(), instance)
class ForeignRelatedObjectsDescriptor(object):
"""
Accessor to the related objects manager on the reverse side of a
many-to-one relation.
In the example::
class Choice(Model):
poll = ForeignKey(Place, related_name='choices')
``poll.choices`` is a ``ForeignRelatedObjectsDescriptor`` instance.
"""
def __init__(self, rel):
self.rel = rel
self.field = rel.field
@cached_property
def related_manager_cls(self):
return create_foreign_related_manager(
self.rel.related_model._default_manager.__class__,
self.rel,
)
def __get__(self, instance, instance_type=None):
if instance is None:
return self
return self.related_manager_cls(instance)
def __set__(self, instance, value):
manager = self.__get__(instance)
manager.set(value)
def create_foreign_related_manager(superclass, rel):
"""
Factory function to create a manager that subclasses another manager
(generally the default manager of a given model) and adds behaviors
specific to many-to-one relations.
"""
class RelatedManager(superclass):
def __init__(self, instance):
super(RelatedManager, self).__init__()
self.instance = instance
self.model = rel.related_model
self.field = rel.field
self.core_filters = {self.field.name: instance}
def __call__(self, **kwargs):
# We use **kwargs rather than a kwarg argument to enforce the
# `manager='manager_name'` syntax.
manager = getattr(self.model, kwargs.pop('manager'))
manager_class = create_foreign_related_manager(manager.__class__, rel)
return manager_class(self.instance)
do_not_call_in_templates = True
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
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:
queryset = super(RelatedManager, self).get_queryset()
queryset._add_hints(instance=instances[0])
queryset = queryset.using(queryset._db or self._db)
rel_obj_attr = self.field.get_local_related_value
instance_attr = self.field.get_foreign_related_value
instances_dict = {instance_attr(inst): inst for inst in instances}
query = {'%s__in' % self.field.name: instances}
queryset = queryset.filter(**query)
# Since we just bypassed this class' get_queryset(), we must manage
# the reverse relation manually.
for rel_obj in queryset:
instance = instances_dict[rel_obj_attr(rel_obj)]
setattr(rel_obj, self.field.name, instance)
cache_name = self.field.related_query_name()
return queryset, rel_obj_attr, instance_attr, False, cache_name
def add(self, *objs, **kwargs):
bulk = kwargs.pop('bulk', True)
objs = list(objs)
db = router.db_for_write(self.model, instance=self.instance)
def check_and_update_obj(obj):
if not isinstance(obj, self.model):
raise TypeError("'%s' instance expected, got %r" % (
self.model._meta.object_name, obj,
))
setattr(obj, self.field.name, self.instance)
if bulk:
pks = []
for obj in objs:
check_and_update_obj(obj)
if obj._state.adding or obj._state.db != db:
raise ValueError(
"%r instance isn't saved. Use bulk=False or save "
"the object first." % obj
)
pks.append(obj.pk)
self.model._base_manager.using(db).filter(pk__in=pks).update(**{
self.field.name: self.instance,
})
else:
with transaction.atomic(using=db, savepoint=False):
for obj in objs:
check_and_update_obj(obj)
obj.save()
add.alters_data = True
def create(self, **kwargs):
kwargs[self.field.name] = self.instance
db = router.db_for_write(self.model, instance=self.instance)
return super(RelatedManager, self.db_manager(db)).create(**kwargs)
create.alters_data = True
def get_or_create(self, **kwargs):
kwargs[self.field.name] = self.instance
db = router.db_for_write(self.model, instance=self.instance)
return super(RelatedManager, self.db_manager(db)).get_or_create(**kwargs)
get_or_create.alters_data = True
def update_or_create(self, **kwargs):
kwargs[self.field.name] = self.instance
db = router.db_for_write(self.model, instance=self.instance)
return super(RelatedManager, self.db_manager(db)).update_or_create(**kwargs)
update_or_create.alters_data = True
# remove() and clear() are only provided if the ForeignKey can have a value of null.
if rel.field.null:
def remove(self, *objs, **kwargs):
if not objs:
return
bulk = kwargs.pop('bulk', True)
val = self.field.get_foreign_related_value(self.instance)
old_ids = set()
for obj in objs:
# Is obj actually part of this descriptor set?
if self.field.get_local_related_value(obj) == val:
old_ids.add(obj.pk)
else:
raise self.field.remote_field.model.DoesNotExist(
"%r is not related to %r." % (obj, self.instance)
)
self._clear(self.filter(pk__in=old_ids), bulk)
remove.alters_data = True
def clear(self, **kwargs):
bulk = kwargs.pop('bulk', True)
self._clear(self, bulk)
clear.alters_data = True
def _clear(self, queryset, bulk):
db = router.db_for_write(self.model, instance=self.instance)
queryset = queryset.using(db)
if bulk:
# `QuerySet.update()` is intrinsically atomic.
queryset.update(**{self.field.name: None})
else:
with transaction.atomic(using=db, savepoint=False):
for obj in queryset:
setattr(obj, self.field.name, None)
obj.save(update_fields=[self.field.name])
_clear.alters_data = True
def set(self, objs, **kwargs):
# Force evaluation of `objs` in case it's a queryset whose value
# could be affected by `manager.clear()`. Refs #19816.
objs = tuple(objs)
bulk = kwargs.pop('bulk', True)
clear = kwargs.pop('clear', False)
if self.field.null:
db = router.db_for_write(self.model, instance=self.instance)
with transaction.atomic(using=db, savepoint=False):
if clear:
self.clear()
self.add(*objs, bulk=bulk)
else:
old_objs = set(self.using(db).all())
new_objs = []
for obj in objs:
if obj in old_objs:
old_objs.remove(obj)
else:
new_objs.append(obj)
self.remove(*old_objs, bulk=bulk)
self.add(*new_objs, bulk=bulk)
else:
self.add(*objs, bulk=bulk)
set.alters_data = True
return RelatedManager
class ManyRelatedObjectsDescriptor(ForeignRelatedObjectsDescriptor):
"""
Accessor to the related objects manager on the forward and reverse sides of
a many-to-many relation.
In the example::
class Pizza(Model):
toppings = ManyToManyField(Topping, related_name='pizzas')
``pizza.toppings`` and ``topping.pizzas`` are ManyRelatedObjectsDescriptor
instances.
"""
def __init__(self, rel, reverse=False):
super(ManyRelatedObjectsDescriptor, self).__init__(rel)
self.reverse = reverse
@property
def through(self):
# through is provided so that you have easy access to the through
# model (Book.authors.through) for inlines, etc. This is done as
# a property to ensure that the fully resolved value is returned.
return self.rel.through
@cached_property
def related_manager_cls(self):
model = self.rel.related_model if self.reverse else self.rel.model
return create_many_related_manager(
model._default_manager.__class__,
self.rel,
reverse=self.reverse,
)
def create_many_related_manager(superclass, rel, reverse):
"""
Factory function to create a manager that subclasses another manager
(generally the default manager of a given model) and adds behaviors
specific to many-to-many relations.
"""
class ManyRelatedManager(superclass):
def __init__(self, instance=None):
super(ManyRelatedManager, self).__init__()
self.instance = instance
if not reverse:
self.model = rel.model
self.query_field_name = rel.field.related_query_name()
self.prefetch_cache_name = rel.field.name
self.source_field_name = rel.field.m2m_field_name()
self.target_field_name = rel.field.m2m_reverse_field_name()
self.symmetrical = rel.symmetrical
else:
self.model = rel.related_model
self.query_field_name = rel.field.name
self.prefetch_cache_name = rel.field.related_query_name()
self.source_field_name = rel.field.m2m_reverse_field_name()
self.target_field_name = rel.field.m2m_field_name()
self.symmetrical = False
self.through = rel.through
self.reverse = reverse
self.source_field = self.through._meta.get_field(self.source_field_name)
self.target_field = self.through._meta.get_field(self.target_field_name)
self.core_filters = {}
for lh_field, rh_field in self.source_field.related_fields:
core_filter_key = '%s__%s' % (self.query_field_name, rh_field.name)
self.core_filters[core_filter_key] = getattr(instance, rh_field.attname)
self.related_val = self.source_field.get_foreign_related_value(instance)
if None in self.related_val:
raise ValueError('"%r" needs to have a value for field "%s" before '
'this many-to-many relationship can be used.' %
(instance, self.source_field_name))
# Even if this relation is not to pk, we require still pk value.
# The wish is that the instance has been already saved to DB,
# although having a pk value isn't a guarantee of that.
if instance.pk is None:
raise ValueError("%r instance needs to have a primary key value before "
"a many-to-many relationship can be used." %
instance.__class__.__name__)
def __call__(self, **kwargs):
# We use **kwargs rather than a kwarg argument to enforce the
# `manager='manager_name'` syntax.
manager = getattr(self.model, kwargs.pop('manager'))
manager_class = create_many_related_manager(manager.__class__, rel, reverse)
return manager_class(instance=self.instance)
do_not_call_in_templates = True
def _build_remove_filters(self, removed_vals):
filters = Q(**{self.source_field_name: self.related_val})
# No need to add a subquery condition if removed_vals is a QuerySet without
# filters.
removed_vals_filters = (not isinstance(removed_vals, QuerySet) or
removed_vals._has_filters())
if removed_vals_filters:
filters &= Q(**{'%s__in' % self.target_field_name: removed_vals})
if self.symmetrical:
symmetrical_filters = Q(**{self.target_field_name: self.related_val})
if removed_vals_filters:
symmetrical_filters &= Q(
**{'%s__in' % self.source_field_name: removed_vals})
filters |= symmetrical_filters
return 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)
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:
queryset = super(ManyRelatedManager, self).get_queryset()
queryset._add_hints(instance=instances[0])
queryset = queryset.using(queryset._db or self._db)
query = {'%s__in' % self.query_field_name: instances}
queryset = queryset._next_is_sticky().filter(**query)
# M2M: need to annotate the query in order to get the primary model
# that the secondary model was actually related to. We know that
# there will already be a join on the join table, so we can just add
# the select.
# For non-autocreated 'through' models, can't assume we are
# dealing with PK values.
fk = self.through._meta.get_field(self.source_field_name)
join_table = self.through._meta.db_table
connection = connections[queryset.db]
qn = connection.ops.quote_name
queryset = queryset.extra(select={
'_prefetch_related_val_%s' % f.attname:
'%s.%s' % (qn(join_table), qn(f.column)) for f in fk.local_related_fields})
return (
queryset,
lambda result: tuple(
getattr(result, '_prefetch_related_val_%s' % f.attname)
for f in fk.local_related_fields
),
lambda inst: tuple(
f.get_db_prep_value(getattr(inst, f.attname), connection)
for f in fk.foreign_related_fields
),
False,
self.prefetch_cache_name,
)
def add(self, *objs):
if not rel.through._meta.auto_created:
opts = self.through._meta
raise AttributeError(
"Cannot use add() on a ManyToManyField which specifies an "
"intermediary model. Use %s.%s's Manager instead." %
(opts.app_label, opts.object_name)
)
db = router.db_for_write(self.through, instance=self.instance)
with transaction.atomic(using=db, savepoint=False):
self._add_items(self.source_field_name, self.target_field_name, *objs)
# If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table
if self.symmetrical:
self._add_items(self.target_field_name, self.source_field_name, *objs)
add.alters_data = True
def remove(self, *objs):
if not rel.through._meta.auto_created:
opts = self.through._meta
raise AttributeError(
"Cannot use remove() on a ManyToManyField which specifies "
"an intermediary model. Use %s.%s's Manager instead." %
(opts.app_label, opts.object_name)
)
self._remove_items(self.source_field_name, self.target_field_name, *objs)
remove.alters_data = True
def clear(self):
db = router.db_for_write(self.through, instance=self.instance)
with transaction.atomic(using=db, savepoint=False):
signals.m2m_changed.send(sender=self.through, action="pre_clear",
instance=self.instance, reverse=self.reverse,
model=self.model, pk_set=None, using=db)
filters = self._build_remove_filters(super(ManyRelatedManager, self).get_queryset().using(db))
self.through._default_manager.using(db).filter(filters).delete()
signals.m2m_changed.send(sender=self.through, action="post_clear",
instance=self.instance, reverse=self.reverse,
model=self.model, pk_set=None, using=db)
clear.alters_data = True
def set(self, objs, **kwargs):
if not rel.through._meta.auto_created:
opts = self.through._meta
raise AttributeError(
"Cannot set values on a ManyToManyField which specifies an "
"intermediary model. Use %s.%s's Manager instead." %
(opts.app_label, opts.object_name)
)
# Force evaluation of `objs` in case it's a queryset whose value
# could be affected by `manager.clear()`. Refs #19816.
objs = tuple(objs)
clear = kwargs.pop('clear', False)
db = router.db_for_write(self.through, instance=self.instance)
with transaction.atomic(using=db, savepoint=False):
if clear:
self.clear()
self.add(*objs)
else:
old_ids = set(self.using(db).values_list(self.target_field.target_field.attname, flat=True))
new_objs = []
for obj in objs:
fk_val = (self.target_field.get_foreign_related_value(obj)[0]
if isinstance(obj, self.model) else obj)
if fk_val in old_ids:
old_ids.remove(fk_val)
else:
new_objs.append(obj)
self.remove(*old_ids)
self.add(*new_objs)
set.alters_data = True
def create(self, **kwargs):
# This check needs to be done here, since we can't later remove this
# from the method lookup table, as we do with add and remove.
if not self.through._meta.auto_created:
opts = self.through._meta
raise AttributeError(
"Cannot use create() on a ManyToManyField which specifies "
"an intermediary model. Use %s.%s's Manager instead." %
(opts.app_label, opts.object_name)
)
db = router.db_for_write(self.instance.__class__, instance=self.instance)
new_obj = super(ManyRelatedManager, self.db_manager(db)).create(**kwargs)
self.add(new_obj)
return new_obj
create.alters_data = True
def get_or_create(self, **kwargs):
db = router.db_for_write(self.instance.__class__, instance=self.instance)
obj, created = super(ManyRelatedManager, self.db_manager(db)).get_or_create(**kwargs)
# We only need to add() if created because if we got an object back
# from get() then the relationship already exists.
if created:
self.add(obj)
return obj, created
get_or_create.alters_data = True
def update_or_create(self, **kwargs):
db = router.db_for_write(self.instance.__class__, instance=self.instance)
obj, created = super(ManyRelatedManager, self.db_manager(db)).update_or_create(**kwargs)
# We only need to add() if created because if we got an object back
# from get() then the relationship already exists.
if created:
self.add(obj)
return obj, created
update_or_create.alters_data = True
def _add_items(self, source_field_name, target_field_name, *objs):
# source_field_name: the PK fieldname in join table for the source object
# target_field_name: the PK fieldname in join table for the target object
# *objs - objects to add. Either object instances, or primary keys of object instances.
# If there aren't any objects, there is nothing to do.
from django.db.models import Model
if objs:
new_ids = set()
for obj in objs:
if isinstance(obj, self.model):
if not router.allow_relation(obj, self.instance):
raise ValueError(
'Cannot add "%r": instance is on database "%s", value is on database "%s"' %
(obj, self.instance._state.db, obj._state.db)
)
fk_val = self.through._meta.get_field(
target_field_name).get_foreign_related_value(obj)[0]
if fk_val is None:
raise ValueError(
'Cannot add "%r": the value for field "%s" is None' %
(obj, target_field_name)
)
new_ids.add(fk_val)
elif isinstance(obj, Model):
raise TypeError(
"'%s' instance expected, got %r" %
(self.model._meta.object_name, obj)
)
else:
new_ids.add(obj)
db = router.db_for_write(self.through, instance=self.instance)
vals = (self.through._default_manager.using(db)
.values_list(target_field_name, flat=True)
.filter(**{
source_field_name: self.related_val[0],
'%s__in' % target_field_name: new_ids,
}))
new_ids = new_ids - set(vals)
with transaction.atomic(using=db, savepoint=False):
if self.reverse or source_field_name == self.source_field_name:
# Don't send the signal when we are inserting the
# duplicate data row for symmetrical reverse entries.
signals.m2m_changed.send(sender=self.through, action='pre_add',
instance=self.instance, reverse=self.reverse,
model=self.model, pk_set=new_ids, using=db)
# Add the ones that aren't there already
self.through._default_manager.using(db).bulk_create([
self.through(**{
'%s_id' % source_field_name: self.related_val[0],
'%s_id' % target_field_name: obj_id,
})
for obj_id in new_ids
])
if self.reverse or source_field_name == self.source_field_name:
# Don't send the signal when we are inserting the
# duplicate data row for symmetrical reverse entries.
signals.m2m_changed.send(sender=self.through, action='post_add',
instance=self.instance, reverse=self.reverse,
model=self.model, pk_set=new_ids, using=db)
def _remove_items(self, source_field_name, target_field_name, *objs):
# source_field_name: the PK colname in join table for the source object
# target_field_name: the PK colname in join table for the target object
# *objs - objects to remove
if not objs:
return
# Check that all the objects are of the right type
old_ids = set()
for obj in objs:
if isinstance(obj, self.model):
fk_val = self.target_field.get_foreign_related_value(obj)[0]
old_ids.add(fk_val)
else:
old_ids.add(obj)
db = router.db_for_write(self.through, instance=self.instance)
with transaction.atomic(using=db, savepoint=False):
# Send a signal to the other end if need be.
signals.m2m_changed.send(sender=self.through, action="pre_remove",
instance=self.instance, reverse=self.reverse,
model=self.model, pk_set=old_ids, using=db)
target_model_qs = super(ManyRelatedManager, self).get_queryset()
if target_model_qs._has_filters():
old_vals = target_model_qs.using(db).filter(**{
'%s__in' % self.target_field.target_field.attname: old_ids})
else:
old_vals = old_ids
filters = self._build_remove_filters(old_vals)
self.through._default_manager.using(db).filter(filters).delete()
signals.m2m_changed.send(sender=self.through, action="post_remove",
instance=self.instance, reverse=self.reverse,
model=self.model, pk_set=old_ids, using=db)
return ManyRelatedManager

304
django/db/models/fields/reverse_related.py Normal file
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from __future__ import unicode_literals
import warnings
from django.core import exceptions
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.encoding import smart_text
from django.utils.functional import cached_property
from . import BLANK_CHOICE_DASH
class ForeignObjectRel(object):
"""
Used by ForeignObject to store information about the relation.
``_meta.get_fields()`` returns this class to provide access to the field
flags for the reverse relation.
"""
# Field flags
auto_created = True
concrete = False
editable = False
is_relation = True
# Reverse relations are always nullable (Django can't enforce that a
# foreign key on the related model points to this model).
null = True
def __init__(self, field, to, related_name=None, related_query_name=None,
limit_choices_to=None, parent_link=False, on_delete=None):
self.field = field
self.model = to
self.related_name = related_name
self.related_query_name = related_query_name
self.limit_choices_to = {} if limit_choices_to is None else limit_choices_to
self.parent_link = parent_link
self.on_delete = on_delete
self.symmetrical = False
self.multiple = True
# Some of the following cached_properties can't be initialized in
# __init__ as the field doesn't have its model yet. Calling these methods
# before field.contribute_to_class() has been called will result in
# AttributeError
@property
def to(self):
warnings.warn(
"Usage of ForeignObjectRel.to attribute has been deprecated. "
"Use the model attribute instead.",
RemovedInDjango20Warning, 2)
return self.model
@cached_property
def hidden(self):
return self.is_hidden()
@cached_property
def name(self):
return self.field.related_query_name()
@property
def remote_field(self):
return self.field
@property
def target_field(self):
"""
When filtering against this relation, returns the field on the remote
model against which the filtering should happen.
"""
target_fields = self.get_path_info()[-1].target_fields
if len(target_fields) > 1:
raise exceptions.FieldError("Can't use target_field for multicolumn relations.")
return target_fields[0]
@cached_property
def related_model(self):
if not self.field.model:
raise AttributeError(
"This property can't be accessed before self.field.contribute_to_class has been called.")
return self.field.model
@cached_property
def many_to_many(self):
return self.field.many_to_many
@cached_property
def many_to_one(self):
return self.field.one_to_many
@cached_property
def one_to_many(self):
return self.field.many_to_one
@cached_property
def one_to_one(self):
return self.field.one_to_one
def get_prep_lookup(self, lookup_name, value):
return self.field.get_prep_lookup(lookup_name, value)
def get_lookup(self, lookup_name):
return self.field.get_lookup(lookup_name)
def get_internal_type(self):
return self.field.get_internal_type()
@property
def db_type(self):
return self.field.db_type
def __repr__(self):
return '<%s: %s.%s>' % (
type(self).__name__,
self.related_model._meta.app_label,
self.related_model._meta.model_name,
)
def get_choices(self, include_blank=True, blank_choice=BLANK_CHOICE_DASH,
limit_to_currently_related=False):
"""
Return choices with a default blank choices included, for use as
SelectField choices for this field.
Analog of django.db.models.fields.Field.get_choices(), provided
initially for utilization by RelatedFieldListFilter.
"""
first_choice = blank_choice if include_blank else []
queryset = self.related_model._default_manager.all()
if limit_to_currently_related:
queryset = queryset.complex_filter(
{'%s__isnull' % self.related_model._meta.model_name: False}
)
lst = [(x._get_pk_val(), smart_text(x)) for x in queryset]
return first_choice + lst
def get_db_prep_lookup(self, lookup_type, value, connection, prepared=False):
# Defer to the actual field definition for db prep
return self.field.get_db_prep_lookup(lookup_type, value, connection=connection, prepared=prepared)
def is_hidden(self):
"Should the related object be hidden?"
return self.related_name is not None and self.related_name[-1] == '+'
def get_joining_columns(self):
return self.field.get_reverse_joining_columns()
def get_extra_restriction(self, where_class, alias, related_alias):
return self.field.get_extra_restriction(where_class, related_alias, alias)
def set_field_name(self):
"""
Set the related field's name, this is not available until later stages
of app loading, so set_field_name is called from
set_attributes_from_rel()
"""
# By default foreign object doesn't relate to any remote field (for
# example custom multicolumn joins currently have no remote field).
self.field_name = None
def get_accessor_name(self, model=None):
# This method encapsulates the logic that decides what name to give an
# accessor descriptor that retrieves related many-to-one or
# many-to-many objects. It uses the lower-cased object_name + "_set",
# but this can be overridden with the "related_name" option.
# Due to backwards compatibility ModelForms need to be able to provide
# an alternate model. See BaseInlineFormSet.get_default_prefix().
opts = model._meta if model else self.related_model._meta
model = model or self.related_model
if self.multiple:
# If this is a symmetrical m2m relation on self, there is no reverse accessor.
if self.symmetrical and model == self.model:
return None
if self.related_name:
return self.related_name
if opts.default_related_name:
return opts.default_related_name % {
'model_name': opts.model_name.lower(),
'app_label': opts.app_label.lower(),
}
return opts.model_name + ('_set' if self.multiple else '')
def get_cache_name(self):
return "_%s_cache" % self.get_accessor_name()
def get_path_info(self):
return self.field.get_reverse_path_info()
class ManyToOneRel(ForeignObjectRel):
"""
Used by the ForeignKey field to store information about the relation.
``_meta.get_fields()`` returns this class to provide access to the field
flags for the reverse relation.
Note: Because we somewhat abuse the Rel objects by using them as reverse
fields we get the funny situation where
``ManyToOneRel.many_to_one == False`` and
``ManyToOneRel.one_to_many == True``. This is unfortunate but the actual
ManyToOneRel class is a private API and there is work underway to turn
reverse relations into actual fields.
"""
def __init__(self, field, to, field_name, related_name=None, related_query_name=None,
limit_choices_to=None, parent_link=False, on_delete=None):
super(ManyToOneRel, self).__init__(
field, to,
related_name=related_name,
related_query_name=related_query_name,
limit_choices_to=limit_choices_to,
parent_link=parent_link,
on_delete=on_delete,
)
self.field_name = field_name
def __getstate__(self):
state = self.__dict__.copy()
state.pop('related_model', None)
return state
def get_related_field(self):
"""
Return the Field in the 'to' object to which this relationship is tied.
"""
field = self.model._meta.get_field(self.field_name)
if not field.concrete:
raise exceptions.FieldDoesNotExist("No related field named '%s'" %
self.field_name)
return field
def set_field_name(self):
self.field_name = self.field_name or self.model._meta.pk.name
class OneToOneRel(ManyToOneRel):
"""
Used by OneToOneField to store information about the relation.
``_meta.get_fields()`` returns this class to provide access to the field
flags for the reverse relation.
"""
def __init__(self, field, to, field_name, related_name=None, related_query_name=None,
limit_choices_to=None, parent_link=False, on_delete=None):
super(OneToOneRel, self).__init__(
field, to, field_name,
related_name=related_name,
related_query_name=related_query_name,
limit_choices_to=limit_choices_to,
parent_link=parent_link,
on_delete=on_delete,
)
self.multiple = False
class ManyToManyRel(ForeignObjectRel):
"""
Used by ManyToManyField to store information about the relation.
``_meta.get_fields()`` returns this class to provide access to the field
flags for the reverse relation.
"""
def __init__(self, field, to, related_name=None, related_query_name=None,
limit_choices_to=None, symmetrical=True, through=None, through_fields=None,
db_constraint=True):
super(ManyToManyRel, self).__init__(
field, to,
related_name=related_name,
related_query_name=related_query_name,
limit_choices_to=limit_choices_to,
)
if through and not db_constraint:
raise ValueError("Can't supply a through model and db_constraint=False")
self.through = through
if through_fields and not through:
raise ValueError("Cannot specify through_fields without a through model")
self.through_fields = through_fields
self.symmetrical = symmetrical
self.db_constraint = db_constraint
def get_related_field(self):
"""
Return the field in the 'to' object to which this relationship is tied.
Provided for symmetry with ManyToOneRel.
"""
opts = self.through._meta
if self.through_fields:
field = opts.get_field(self.through_fields[0])
else:
for field in opts.fields:
rel = getattr(field, 'remote_field', None)
if rel and rel.model == self.model:
break
return field.foreign_related_fields[0]