108 kB

	"""
	The main QuerySet implementation. This provides the public API for the ORM.
	"""

	import copy
	import operator
	import warnings
	from contextlib import nullcontext
	from functools import reduce
	from itertools import chain, islice

	from asgiref.sync import sync_to_async

	import django
	from django.conf import settings
	from django.core import exceptions
	from django.db import (
	DJANGO_VERSION_PICKLE_KEY,
	IntegrityError,
	NotSupportedError,
	connections,
	router,
	transaction,
	)
	from django.db.models import AutoField, DateField, DateTimeField, Field, Max, sql
	from django.db.models.constants import LOOKUP_SEP, OnConflict
	from django.db.models.deletion import Collector
	from django.db.models.expressions import Case, DatabaseDefault, F, Value, When
	from django.db.models.functions import Cast, Trunc
	from django.db.models.query_utils import FilteredRelation, Q
	from django.db.models.sql.constants import GET_ITERATOR_CHUNK_SIZE, ROW_COUNT
	from django.db.models.utils import (
	AltersData,
	create_namedtuple_class,
	resolve_callables,
	)
	from django.utils import timezone
	from django.utils.deprecation import RemovedInDjango70Warning
	from django.utils.functional import cached_property

	# The maximum number of results to fetch in a get() query.
	MAX_GET_RESULTS = 21

	# The maximum number of items to display in a QuerySet.__repr__
	REPR_OUTPUT_SIZE = 20

	PROHIBITED_FILTER_KWARGS = frozenset(["_connector", "_negated"])


	class BaseIterable:
	def __init__(
	self, queryset, chunked_fetch=False, chunk_size=GET_ITERATOR_CHUNK_SIZE
	):
	self.queryset = queryset
	self.chunked_fetch = chunked_fetch
	self.chunk_size = chunk_size

	async def _async_generator(self):
	# Generators don't actually start running until the first time you call
	# next() on them, so make the generator object in the async thread and
	# then repeatedly dispatch to it in a sync thread.
	sync_generator = self.__iter__()

	def next_slice(gen):
	return list(islice(gen, self.chunk_size))

	while True:
	chunk = await sync_to_async(next_slice)(sync_generator)
	for item in chunk:
	yield item
	if len(chunk) < self.chunk_size:
	break

	# __aiter__() is a synchronous method that has to then return an
	# asynchronous iterator/generator. Thus, nest an async generator inside
	# it.
	# This is a generic iterable converter for now, and is going to suffer a
	# performance penalty on large sets of items due to the cost of crossing
	# over the sync barrier for each chunk. Custom __aiter__() methods should
	# be added to each Iterable subclass, but that needs some work in the
	# Compiler first.
	def __aiter__(self):
	return self._async_generator()


	class ModelIterable(BaseIterable):
	"""Iterable that yields a model instance for each row."""

	def __iter__(self):
	queryset = self.queryset
	db = queryset.db
	compiler = queryset.query.get_compiler(using=db)
	# Execute the query. This will also fill compiler.select, klass_info,
	# and annotations.
	results = compiler.execute_sql(
	chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size
	)
	select, klass_info, annotation_col_map = (
	compiler.select,
	compiler.klass_info,
	compiler.annotation_col_map,
	)
	model_cls = klass_info["model"]
	select_fields = klass_info["select_fields"]
	model_fields_start, model_fields_end = select_fields[0], select_fields[-1] + 1
	init_list = [
	f[0].target.attname for f in select[model_fields_start:model_fields_end]
	]
	related_populators = get_related_populators(klass_info, select, db)
	known_related_objects = [
	(
	field,
	related_objs,
	operator.attrgetter(
	*[
	(
	field.attname
	if from_field == "self"
	else queryset.model._meta.get_field(from_field).attname
	)
	for from_field in field.from_fields
	]
	),
	)
	for field, related_objs in queryset._known_related_objects.items()
	]
	for row in compiler.results_iter(results):
	obj = model_cls.from_db(
	db, init_list, row[model_fields_start:model_fields_end]
	)
	for rel_populator in related_populators:
	rel_populator.populate(row, obj)
	if annotation_col_map:
	for attr_name, col_pos in annotation_col_map.items():
	setattr(obj, attr_name, row[col_pos])

	# Add the known related objects to the model.
	for field, rel_objs, rel_getter in known_related_objects:
	# Avoid overwriting objects loaded by, e.g., select_related().
	if field.is_cached(obj):
	continue
	rel_obj_id = rel_getter(obj)
	try:
	rel_obj = rel_objs[rel_obj_id]
	except KeyError:
	pass # May happen in qs1 \| qs2 scenarios.
	else:
	setattr(obj, field.name, rel_obj)

	yield obj


	class RawModelIterable(BaseIterable):
	"""
	Iterable that yields a model instance for each row from a raw queryset.
	"""

	def __iter__(self):
	# Cache some things for performance reasons outside the loop.
	db = self.queryset.db
	query = self.queryset.query
	connection = connections[db]
	compiler = connection.ops.compiler("SQLCompiler")(query, connection, db)
	query_iterator = iter(query)

	try:
	(
	model_init_names,
	model_init_pos,
	annotation_fields,
	) = self.queryset.resolve_model_init_order()
	model_cls = self.queryset.model
	if any(
	f.attname not in model_init_names for f in model_cls._meta.pk_fields
	):
	raise exceptions.FieldDoesNotExist(
	"Raw query must include the primary key"
	)
	fields = [self.queryset.model_fields.get(c) for c in self.queryset.columns]
	cols = [f.get_col(f.model._meta.db_table) if f else None for f in fields]
	converters = compiler.get_converters(cols)
	if converters:
	query_iterator = compiler.apply_converters(query_iterator, converters)
	if compiler.has_composite_fields(cols):
	query_iterator = compiler.composite_fields_to_tuples(
	query_iterator, cols
	)
	for values in query_iterator:
	# Associate fields to values
	model_init_values = [values[pos] for pos in model_init_pos]
	instance = model_cls.from_db(db, model_init_names, model_init_values)
	if annotation_fields:
	for column, pos in annotation_fields:
	setattr(instance, column, values[pos])
	yield instance
	finally:
	# Done iterating the Query. If it has its own cursor, close it.
	if hasattr(query, "cursor") and query.cursor:
	query.cursor.close()


	class ValuesIterable(BaseIterable):
	"""
	Iterable returned by QuerySet.values() that yields a dict for each row.
	"""

	def __iter__(self):
	queryset = self.queryset
	query = queryset.query
	compiler = query.get_compiler(queryset.db)

	if query.selected:
	names = list(query.selected)
	else:
	# extra(select=...) cols are always at the start of the row.
	names = [
	*query.extra_select,
	*query.values_select,
	*query.annotation_select,
	]
	indexes = range(len(names))
	for row in compiler.results_iter(
	chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size
	):
	yield {names[i]: row[i] for i in indexes}


	class ValuesListIterable(BaseIterable):
	"""
	Iterable returned by QuerySet.values_list(flat=False) that yields a tuple
	for each row.
	"""

	def __iter__(self):
	queryset = self.queryset
	query = queryset.query
	compiler = query.get_compiler(queryset.db)
	return compiler.results_iter(
	tuple_expected=True,
	chunked_fetch=self.chunked_fetch,
	chunk_size=self.chunk_size,
	)


	class NamedValuesListIterable(ValuesListIterable):
	"""
	Iterable returned by QuerySet.values_list(named=True) that yields a
	namedtuple for each row.
	"""

	def __iter__(self):
	queryset = self.queryset
	if queryset._fields:
	names = queryset._fields
	else:
	query = queryset.query
	names = [
	*query.extra_select,
	*query.values_select,
	*query.annotation_select,
	]
	tuple_class = create_namedtuple_class(*names)
	new = tuple.__new__
	for row in super().__iter__():
	yield new(tuple_class, row)


	class FlatValuesListIterable(BaseIterable):
	"""
	Iterable returned by QuerySet.values_list(flat=True) that yields single
	values.
	"""

	def __iter__(self):
	queryset = self.queryset
	compiler = queryset.query.get_compiler(queryset.db)
	for row in compiler.results_iter(
	chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size
	):
	yield row[0]


	class QuerySet(AltersData):
	"""Represent a lazy database lookup for a set of objects."""

	def __init__(self, model=None, query=None, using=None, hints=None):
	self.model = model
	self._db = using
	self._hints = hints or {}
	self._query = query or sql.Query(self.model)
	self._result_cache = None
	self._sticky_filter = False
	self._for_write = False
	self._prefetch_related_lookups = ()
	self._prefetch_done = False
	self._known_related_objects = {} # {rel_field: {pk: rel_obj}}
	self._iterable_class = ModelIterable
	self._fields = None
	self._defer_next_filter = False
	self._deferred_filter = None

	@property
	def query(self):
	if self._deferred_filter:
	negate, args, kwargs = self._deferred_filter
	self._filter_or_exclude_inplace(negate, args, kwargs)
	self._deferred_filter = None
	return self._query

	@query.setter
	def query(self, value):
	if value.values_select:
	self._iterable_class = ValuesIterable
	self._query = value

	def as_manager(cls):
	# Address the circular dependency between `Queryset` and `Manager`.
	from django.db.models.manager import Manager

	manager = Manager.from_queryset(cls)()
	manager._built_with_as_manager = True
	return manager

	as_manager.queryset_only = True
	as_manager = classmethod(as_manager)

	########################
	# PYTHON MAGIC METHODS #
	########################

	def __deepcopy__(self, memo):
	"""Don't populate the QuerySet's cache."""
	obj = self.__class__()
	for k, v in self.__dict__.items():
	if k == "_result_cache":
	obj.__dict__[k] = None
	else:
	obj.__dict__[k] = copy.deepcopy(v, memo)
	return obj

	def __getstate__(self):
	# Force the cache to be fully populated.
	self._fetch_all()
	return {**self.__dict__, DJANGO_VERSION_PICKLE_KEY: django.__version__}

	def __setstate__(self, state):
	pickled_version = state.get(DJANGO_VERSION_PICKLE_KEY)
	if pickled_version:
	if pickled_version != django.__version__:
	warnings.warn(
	"Pickled queryset instance's Django version %s does not "
	"match the current version %s."
	% (pickled_version, django.__version__),
	RuntimeWarning,
	stacklevel=2,
	)
	else:
	warnings.warn(
	"Pickled queryset instance's Django version is not specified.",
	RuntimeWarning,
	stacklevel=2,
	)
	self.__dict__.update(state)

	def __repr__(self):
	data = list(self[: REPR_OUTPUT_SIZE + 1])
	if len(data) > REPR_OUTPUT_SIZE:
	data[-1] = "...(remaining elements truncated)..."
	return "<%s %r>" % (self.__class__.__name__, data)

	def __len__(self):
	self._fetch_all()
	return len(self._result_cache)

	def __iter__(self):
	"""
	The queryset iterator protocol uses three nested iterators in the
	default case:
	1. sql.compiler.execute_sql()
	- Returns 100 rows at time (constants.GET_ITERATOR_CHUNK_SIZE)
	using cursor.fetchmany(). This part is responsible for
	doing some column masking, and returning the rows in chunks.
	2. sql.compiler.results_iter()
	- Returns one row at time. At this point the rows are still just
	tuples. In some cases the return values are converted to
	Python values at this location.
	3. self.iterator()
	- Responsible for turning the rows into model objects.
	"""
	self._fetch_all()
	return iter(self._result_cache)

	def __aiter__(self):
	# Remember, __aiter__ itself is synchronous, it's the thing it returns
	# that is async!
	async def generator():
	await sync_to_async(self._fetch_all)()
	for item in self._result_cache:
	yield item

	return generator()

	def __bool__(self):
	self._fetch_all()
	return bool(self._result_cache)

	def __getitem__(self, k):
	"""Retrieve an item or slice from the set of results."""
	if not isinstance(k, (int, slice)):
	raise TypeError(
	"QuerySet indices must be integers or slices, not %s."
	% type(k).__name__
	)
	if (isinstance(k, int) and k < 0) or (
	isinstance(k, slice)
	and (
	(k.start is not None and k.start < 0)
	or (k.stop is not None and k.stop < 0)
	)
	):
	raise ValueError("Negative indexing is not supported.")

	if self._result_cache is not None:
	return self._result_cache[k]

	if isinstance(k, slice):
	qs = self._chain()
	if k.start is not None:
	start = int(k.start)
	else:
	start = None
	if k.stop is not None:
	stop = int(k.stop)
	else:
	stop = None
	qs.query.set_limits(start, stop)
	return list(qs)[:: k.step] if k.step else qs

	qs = self._chain()
	qs.query.set_limits(k, k + 1)
	qs._fetch_all()
	return qs._result_cache[0]

	def __class_getitem__(cls, args, *kwargs):
	return cls

	def __and__(self, other):
	self._check_operator_queryset(other, "&")
	self._merge_sanity_check(other)
	if isinstance(other, EmptyQuerySet):
	return other
	if isinstance(self, EmptyQuerySet):
	return self
	combined = self._chain()
	combined._merge_known_related_objects(other)
	combined.query.combine(other.query, sql.AND)
	return combined

	def __or__(self, other):
	self._check_operator_queryset(other, "\|")
	self._merge_sanity_check(other)
	if isinstance(self, EmptyQuerySet):
	return other
	if isinstance(other, EmptyQuerySet):
	return self
	query = (
	self
	if self.query.can_filter()
	else self.model._base_manager.filter(pk__in=self.values("pk"))
	)
	combined = query._chain()
	combined._merge_known_related_objects(other)
	if not other.query.can_filter():
	other = other.model._base_manager.filter(pk__in=other.values("pk"))
	combined.query.combine(other.query, sql.OR)
	return combined

	def __xor__(self, other):
	self._check_operator_queryset(other, "^")
	self._merge_sanity_check(other)
	if isinstance(self, EmptyQuerySet):
	return other
	if isinstance(other, EmptyQuerySet):
	return self
	query = (
	self
	if self.query.can_filter()
	else self.model._base_manager.filter(pk__in=self.values("pk"))
	)
	combined = query._chain()
	combined._merge_known_related_objects(other)
	if not other.query.can_filter():
	other = other.model._base_manager.filter(pk__in=other.values("pk"))
	combined.query.combine(other.query, sql.XOR)
	return combined

	####################################
	# METHODS THAT DO DATABASE QUERIES #
	####################################

	def _iterator(self, use_chunked_fetch, chunk_size):
	iterable = self._iterable_class(
	self,
	chunked_fetch=use_chunked_fetch,
	chunk_size=chunk_size or 2000,
	)
	if not self._prefetch_related_lookups or chunk_size is None:
	yield from iterable
	return

	iterator = iter(iterable)
	while results := list(islice(iterator, chunk_size)):
	prefetch_related_objects(results, *self._prefetch_related_lookups)
	yield from results

	def iterator(self, chunk_size=None):
	"""
	An iterator over the results from applying this QuerySet to the
	database. chunk_size must be provided for QuerySets that prefetch
	related objects. Otherwise, a default chunk_size of 2000 is supplied.
	"""
	if chunk_size is None:
	if self._prefetch_related_lookups:
	raise ValueError(
	"chunk_size must be provided when using QuerySet.iterator() after "
	"prefetch_related()."
	)
	elif chunk_size <= 0:
	raise ValueError("Chunk size must be strictly positive.")
	use_chunked_fetch = not connections[self.db].settings_dict.get(
	"DISABLE_SERVER_SIDE_CURSORS"
	)
	return self._iterator(use_chunked_fetch, chunk_size)

	async def aiterator(self, chunk_size=2000):
	"""
	An asynchronous iterator over the results from applying this QuerySet
	to the database.
	"""
	if chunk_size <= 0:
	raise ValueError("Chunk size must be strictly positive.")
	use_chunked_fetch = not connections[self.db].settings_dict.get(
	"DISABLE_SERVER_SIDE_CURSORS"
	)
	iterable = self._iterable_class(
	self, chunked_fetch=use_chunked_fetch, chunk_size=chunk_size
	)
	if self._prefetch_related_lookups:
	results = []

	async for item in iterable:
	results.append(item)
	if len(results) >= chunk_size:
	await aprefetch_related_objects(
	results, *self._prefetch_related_lookups
	)
	for result in results:
	yield result
	results.clear()

	if results:
	await aprefetch_related_objects(
	results, *self._prefetch_related_lookups
	)
	for result in results:
	yield result
	else:
	async for item in iterable:
	yield item

	def aggregate(self, args, *kwargs):
	"""
	Return a dictionary containing the calculations (aggregation)
	over the current queryset.

	If args is present the expression is passed as a kwarg using
	the Aggregate object's default alias.
	"""
	if self.query.distinct_fields:
	raise NotImplementedError("aggregate() + distinct(fields) not implemented.")
	self._validate_values_are_expressions(
	(args, kwargs.values()), method_name="aggregate"
	)
	for arg in args:
	# The default_alias property raises TypeError if default_alias
	# can't be set automatically or AttributeError if it isn't an
	# attribute.
	try:
	arg.default_alias
	except (AttributeError, TypeError):
	raise TypeError("Complex aggregates require an alias")
	kwargs[arg.default_alias] = arg

	return self.query.chain().get_aggregation(self.db, kwargs)

	async def aaggregate(self, args, *kwargs):
	return await sync_to_async(self.aggregate)(args, *kwargs)

	def count(self):
	"""
	Perform a SELECT COUNT() and return the number of records as an
	integer.

	If the QuerySet is already fully cached, return the length of the
	cached results set to avoid multiple SELECT COUNT(*) calls.
	"""
	if self._result_cache is not None:
	return len(self._result_cache)

	return self.query.get_count(using=self.db)

	async def acount(self):
	return await sync_to_async(self.count)()

	def get(self, args, *kwargs):
	"""
	Perform the query and return a single object matching the given
	keyword arguments.
	"""
	if self.query.combinator and (args or kwargs):
	raise NotSupportedError(
	"Calling QuerySet.get(...) with filters after %s() is not "
	"supported." % self.query.combinator
	)
	clone = self._chain() if self.query.combinator else self.filter(args, *kwargs)
	if self.query.can_filter() and not self.query.distinct_fields:
	clone = clone.order_by()
	limit = None
	if (
	not clone.query.select_for_update
	or connections[clone.db].features.supports_select_for_update_with_limit
	):
	limit = MAX_GET_RESULTS
	clone.query.set_limits(high=limit)
	num = len(clone)
	if num == 1:
	return clone._result_cache[0]
	if not num:
	raise self.model.DoesNotExist(
	"%s matching query does not exist." % self.model._meta.object_name
	)
	raise self.model.MultipleObjectsReturned(
	"get() returned more than one %s -- it returned %s!"
	% (
	self.model._meta.object_name,
	num if not limit or num < limit else "more than %s" % (limit - 1),
	)
	)

	async def aget(self, args, *kwargs):
	return await sync_to_async(self.get)(args, *kwargs)

	def create(self, **kwargs):
	"""
	Create a new object with the given kwargs, saving it to the database
	and returning the created object.
	"""
	reverse_one_to_one_fields = frozenset(kwargs).intersection(
	self.model._meta._reverse_one_to_one_field_names
	)
	if reverse_one_to_one_fields:
	raise ValueError(
	"The following fields do not exist in this model: %s"
	% ", ".join(reverse_one_to_one_fields)
	)

	obj = self.model(**kwargs)
	self._for_write = True
	obj.save(force_insert=True, using=self.db)
	return obj

	create.alters_data = True

	async def acreate(self, **kwargs):
	return await sync_to_async(self.create)(**kwargs)

	acreate.alters_data = True

	def _prepare_for_bulk_create(self, objs):
	objs_with_pk, objs_without_pk = [], []
	for obj in objs:
	if isinstance(obj.pk, DatabaseDefault):
	objs_without_pk.append(obj)
	elif obj._is_pk_set():
	objs_with_pk.append(obj)
	else:
	obj.pk = obj._meta.pk.get_pk_value_on_save(obj)
	if obj._is_pk_set():
	objs_with_pk.append(obj)
	else:
	objs_without_pk.append(obj)
	obj._prepare_related_fields_for_save(operation_name="bulk_create")
	return objs_with_pk, objs_without_pk

	def _check_bulk_create_options(
	self, ignore_conflicts, update_conflicts, update_fields, unique_fields
	):
	if ignore_conflicts and update_conflicts:
	raise ValueError(
	"ignore_conflicts and update_conflicts are mutually exclusive."
	)
	db_features = connections[self.db].features
	if ignore_conflicts:
	if not db_features.supports_ignore_conflicts:
	raise NotSupportedError(
	"This database backend does not support ignoring conflicts."
	)
	return OnConflict.IGNORE
	elif update_conflicts:
	if not db_features.supports_update_conflicts:
	raise NotSupportedError(
	"This database backend does not support updating conflicts."
	)
	if not update_fields:
	raise ValueError(
	"Fields that will be updated when a row insertion fails "
	"on conflicts must be provided."
	)
	if unique_fields and not db_features.supports_update_conflicts_with_target:
	raise NotSupportedError(
	"This database backend does not support updating "
	"conflicts with specifying unique fields that can trigger "
	"the upsert."
	)
	if not unique_fields and db_features.supports_update_conflicts_with_target:
	raise ValueError(
	"Unique fields that can trigger the upsert must be provided."
	)
	# Updating primary keys and non-concrete fields is forbidden.
	if any(not f.concrete for f in update_fields):
	raise ValueError(
	"bulk_create() can only be used with concrete fields in "
	"update_fields."
	)
	if any(f in self.model._meta.pk_fields for f in update_fields):
	raise ValueError(
	"bulk_create() cannot be used with primary keys in "
	"update_fields."
	)
	if unique_fields:
	if any(not f.concrete for f in unique_fields):
	raise ValueError(
	"bulk_create() can only be used with concrete fields "
	"in unique_fields."
	)
	return OnConflict.UPDATE
	return None

	def bulk_create(
	self,
	objs,
	batch_size=None,
	ignore_conflicts=False,
	update_conflicts=False,
	update_fields=None,
	unique_fields=None,
	):
	"""
	Insert each of the instances into the database. Do not call
	save() on each of the instances, do not send any pre/post_save
	signals, and do not set the primary key attribute if it is an
	autoincrement field (except if
	features.can_return_rows_from_bulk_insert=True).
	Multi-table models are not supported.
	"""
	# When you bulk insert you don't get the primary keys back (if it's an
	# autoincrement, except if can_return_rows_from_bulk_insert=True), so
	# you can't insert into the child tables which references this. There
	# are two workarounds:
	# 1) This could be implemented if you didn't have an autoincrement pk
	# 2) You could do it by doing O(n) normal inserts into the parent
	# tables to get the primary keys back and then doing a single bulk
	# insert into the childmost table.
	# We currently set the primary keys on the objects when using
	# PostgreSQL via the RETURNING ID clause. It should be possible for
	# Oracle as well, but the semantics for extracting the primary keys is
	# trickier so it's not done yet.
	if batch_size is not None and batch_size <= 0:
	raise ValueError("Batch size must be a positive integer.")
	# Check that the parents share the same concrete model with the our
	# model to detect the inheritance pattern ConcreteGrandParent ->
	# MultiTableParent -> ProxyChild. Simply checking
	# self.model._meta.proxy would not identify that case as involving
	# multiple tables.
	for parent in self.model._meta.all_parents:
	if parent._meta.concrete_model is not self.model._meta.concrete_model:
	raise ValueError("Can't bulk create a multi-table inherited model")
	if not objs:
	return objs
	opts = self.model._meta
	if unique_fields:
	# Primary key is allowed in unique_fields.
	unique_fields = [
	self.model._meta.get_field(opts.pk.name if name == "pk" else name)
	for name in unique_fields
	]
	if update_fields:
	update_fields = [self.model._meta.get_field(name) for name in update_fields]
	on_conflict = self._check_bulk_create_options(
	ignore_conflicts,
	update_conflicts,
	update_fields,
	unique_fields,
	)
	self._for_write = True
	fields = [f for f in opts.concrete_fields if not f.generated]
	objs = list(objs)
	objs_with_pk, objs_without_pk = self._prepare_for_bulk_create(objs)
	if objs_with_pk and objs_without_pk:
	context = transaction.atomic(using=self.db, savepoint=False)
	else:
	context = nullcontext()
	with context:
	self._handle_order_with_respect_to(objs)
	if objs_with_pk:
	returned_columns = self._batched_insert(
	objs_with_pk,
	fields,
	batch_size,
	on_conflict=on_conflict,
	update_fields=update_fields,
	unique_fields=unique_fields,
	)
	for obj_with_pk, results in zip(objs_with_pk, returned_columns):
	for result, field in zip(results, opts.db_returning_fields):
	if field != opts.pk:
	setattr(obj_with_pk, field.attname, result)
	for obj_with_pk in objs_with_pk:
	obj_with_pk._state.adding = False
	obj_with_pk._state.db = self.db
	if objs_without_pk:
	fields = [f for f in fields if not isinstance(f, AutoField)]
	returned_columns = self._batched_insert(
	objs_without_pk,
	fields,
	batch_size,
	on_conflict=on_conflict,
	update_fields=update_fields,
	unique_fields=unique_fields,
	)
	connection = connections[self.db]
	if (
	connection.features.can_return_rows_from_bulk_insert
	and on_conflict is None
	):
	assert len(returned_columns) == len(objs_without_pk)
	for obj_without_pk, results in zip(objs_without_pk, returned_columns):
	for result, field in zip(results, opts.db_returning_fields):
	setattr(obj_without_pk, field.attname, result)
	obj_without_pk._state.adding = False
	obj_without_pk._state.db = self.db

	return objs

	def _handle_order_with_respect_to(self, objs):
	if objs and (order_wrt := self.model._meta.order_with_respect_to):
	get_filter_kwargs_for_object = order_wrt.get_filter_kwargs_for_object
	attnames = list(get_filter_kwargs_for_object(objs[0]))
	group_keys = set()
	obj_groups = []
	for obj in objs:
	group_key = tuple(get_filter_kwargs_for_object(obj).values())
	group_keys.add(group_key)
	obj_groups.append((obj, group_key))
	filters = [
	Q.create(list(zip(attnames, group_key))) for group_key in group_keys
	]
	next_orders = (
	self.model._base_manager.using(self.db)
	.filter(reduce(operator.or_, filters))
	.values_list(*attnames)
	.annotate(_order__max=Max("_order") + 1)
	)
	# Create mapping of group values to max order.
	group_next_orders = dict.fromkeys(group_keys, 0)
	group_next_orders.update(
	(tuple(group_key), next_order) for *group_key, next_order in next_orders
	)
	# Assign _order values to new objects.
	for obj, group_key in obj_groups:
	if getattr(obj, "_order", None) is None:
	group_next_order = group_next_orders[group_key]
	obj._order = group_next_order
	group_next_orders[group_key] += 1

	bulk_create.alters_data = True

	async def abulk_create(
	self,
	objs,
	batch_size=None,
	ignore_conflicts=False,
	update_conflicts=False,
	update_fields=None,
	unique_fields=None,
	):
	return await sync_to_async(self.bulk_create)(
	objs=objs,
	batch_size=batch_size,
	ignore_conflicts=ignore_conflicts,
	update_conflicts=update_conflicts,
	update_fields=update_fields,
	unique_fields=unique_fields,
	)

	abulk_create.alters_data = True

	def bulk_update(self, objs, fields, batch_size=None):
	"""
	Update the given fields in each of the given objects in the database.
	"""
	if batch_size is not None and batch_size <= 0:
	raise ValueError("Batch size must be a positive integer.")
	if not fields:
	raise ValueError("Field names must be given to bulk_update().")
	objs = tuple(objs)
	if not all(obj._is_pk_set() for obj in objs):
	raise ValueError("All bulk_update() objects must have a primary key set.")
	opts = self.model._meta
	fields = [opts.get_field(name) for name in fields]
	if any(not f.concrete for f in fields):
	raise ValueError("bulk_update() can only be used with concrete fields.")
	all_pk_fields = set(opts.pk_fields)
	for parent in opts.all_parents:
	all_pk_fields.update(parent._meta.pk_fields)
	if any(f in all_pk_fields for f in fields):
	raise ValueError("bulk_update() cannot be used with primary key fields.")
	if not objs:
	return 0
	for obj in objs:
	obj._prepare_related_fields_for_save(
	operation_name="bulk_update", fields=fields
	)
	# PK is used twice in the resulting update query, once in the filter
	# and once in the WHEN. Each field will also have one CAST.
	self._for_write = True
	connection = connections[self.db]
	max_batch_size = connection.ops.bulk_batch_size(
	[opts.pk, opts.pk, *fields], objs
	)
	batch_size = min(batch_size, max_batch_size) if batch_size else max_batch_size
	requires_casting = connection.features.requires_casted_case_in_updates
	batches = (objs[i : i + batch_size] for i in range(0, len(objs), batch_size))
	updates = []
	for batch_objs in batches:
	update_kwargs = {}
	for field in fields:
	when_statements = []
	for obj in batch_objs:
	attr = getattr(obj, field.attname)
	if not hasattr(attr, "resolve_expression"):
	attr = Value(attr, output_field=field)
	when_statements.append(When(pk=obj.pk, then=attr))
	case_statement = Case(*when_statements, output_field=field)
	if requires_casting:
	case_statement = Cast(case_statement, output_field=field)
	update_kwargs[field.attname] = case_statement
	updates.append(([obj.pk for obj in batch_objs], update_kwargs))
	rows_updated = 0
	queryset = self.using(self.db)
	with transaction.atomic(using=self.db, savepoint=False):
	for pks, update_kwargs in updates:
	rows_updated += queryset.filter(pk__in=pks).update(**update_kwargs)
	return rows_updated

	bulk_update.alters_data = True

	async def abulk_update(self, objs, fields, batch_size=None):
	return await sync_to_async(self.bulk_update)(
	objs=objs,
	fields=fields,
	batch_size=batch_size,
	)

	abulk_update.alters_data = True

	def get_or_create(self, defaults=None, **kwargs):
	"""
	Look up an object with the given kwargs, creating one if necessary.
	Return a tuple of (object, created), where created is a boolean
	specifying whether an object was created.
	"""
	# The get() needs to be targeted at the write database in order
	# to avoid potential transaction consistency problems.
	self._for_write = True
	try:
	return self.get(**kwargs), False
	except self.model.DoesNotExist:
	params = self._extract_model_params(defaults, **kwargs)
	# Try to create an object using passed params.
	try:
	with transaction.atomic(using=self.db):
	params = dict(resolve_callables(params))
	return self.create(**params), True
	except IntegrityError:
	try:
	return self.get(**kwargs), False
	except self.model.DoesNotExist:
	pass
	raise

	get_or_create.alters_data = True

	async def aget_or_create(self, defaults=None, **kwargs):
	return await sync_to_async(self.get_or_create)(
	defaults=defaults,
	**kwargs,
	)

	aget_or_create.alters_data = True

	def update_or_create(self, defaults=None, create_defaults=None, **kwargs):
	"""
	Look up an object with the given kwargs, updating one with defaults
	if it exists, otherwise create a new one. Optionally, an object can
	be created with different values than defaults by using
	create_defaults.
	Return a tuple (object, created), where created is a boolean
	specifying whether an object was created.
	"""
	update_defaults = defaults or {}
	if create_defaults is None:
	create_defaults = update_defaults

	self._for_write = True
	with transaction.atomic(using=self.db):
	# Lock the row so that a concurrent update is blocked until
	# update_or_create() has performed its save.
	obj, created = self.select_for_update().get_or_create(
	create_defaults, **kwargs
	)
	if created:
	return obj, created
	for k, v in resolve_callables(update_defaults):
	setattr(obj, k, v)

	update_fields = set(update_defaults)
	concrete_field_names = self.model._meta._non_pk_concrete_field_names
	# update_fields does not support non-concrete fields.
	if concrete_field_names.issuperset(update_fields):
	# Add fields which are set on pre_save(), e.g. auto_now fields.
	# This is to maintain backward compatibility as these fields
	# are not updated unless explicitly specified in the
	# update_fields list.
	pk_fields = self.model._meta.pk_fields
	for field in self.model._meta.local_concrete_fields:
	if not (
	field in pk_fields or field.__class__.pre_save is Field.pre_save
	):
	update_fields.add(field.name)
	if field.name != field.attname:
	update_fields.add(field.attname)
	obj.save(using=self.db, update_fields=update_fields)
	else:
	obj.save(using=self.db)
	return obj, False

	update_or_create.alters_data = True

	async def aupdate_or_create(self, defaults=None, create_defaults=None, **kwargs):
	return await sync_to_async(self.update_or_create)(
	defaults=defaults,
	create_defaults=create_defaults,
	**kwargs,
	)

	aupdate_or_create.alters_data = True

	def _extract_model_params(self, defaults, **kwargs):
	"""
	Prepare `params` for creating a model instance based on the given
	kwargs; for use by get_or_create().
	"""
	defaults = defaults or {}
	params = {k: v for k, v in kwargs.items() if LOOKUP_SEP not in k}
	params.update(defaults)
	property_names = self.model._meta._property_names
	invalid_params = []
	for param in params:
	try:
	self.model._meta.get_field(param)
	except exceptions.FieldDoesNotExist:
	# It's okay to use a model's property if it has a setter.
	if not (param in property_names and getattr(self.model, param).fset):
	invalid_params.append(param)
	if invalid_params:
	raise exceptions.FieldError(
	"Invalid field name(s) for model %s: '%s'."
	% (
	self.model._meta.object_name,
	"', '".join(sorted(invalid_params)),
	)
	)
	return params

	def _earliest(self, *fields):
	"""
	Return the earliest object according to fields (if given) or by the
	model's Meta.get_latest_by.
	"""
	if fields:
	order_by = fields
	else:
	order_by = getattr(self.model._meta, "get_latest_by")
	if order_by and not isinstance(order_by, (tuple, list)):
	order_by = (order_by,)
	if order_by is None:
	raise ValueError(
	"earliest() and latest() require either fields as positional "
	"arguments or 'get_latest_by' in the model's Meta."
	)
	obj = self._chain()
	obj.query.set_limits(high=1)
	obj.query.clear_ordering(force=True)
	obj.query.add_ordering(*order_by)
	return obj.get()

	def earliest(self, *fields):
	if self.query.is_sliced:
	raise TypeError("Cannot change a query once a slice has been taken.")
	return self._earliest(*fields)

	async def aearliest(self, *fields):
	return await sync_to_async(self.earliest)(*fields)

	def latest(self, *fields):
	"""
	Return the latest object according to fields (if given) or by the
	model's Meta.get_latest_by.
	"""
	if self.query.is_sliced:
	raise TypeError("Cannot change a query once a slice has been taken.")
	return self.reverse()._earliest(*fields)

	async def alatest(self, *fields):
	return await sync_to_async(self.latest)(*fields)

	def first(self):
	"""Return the first object of a query or None if no match is found."""
	if self.ordered:
	queryset = self
	else:
	self._check_ordering_first_last_queryset_aggregation(method="first")
	queryset = self.order_by("pk")
	for obj in queryset[:1]:
	return obj

	async def afirst(self):
	return await sync_to_async(self.first)()

	def last(self):
	"""Return the last object of a query or None if no match is found."""
	if self.ordered:
	queryset = self.reverse()
	else:
	self._check_ordering_first_last_queryset_aggregation(method="last")
	queryset = self.order_by("-pk")
	for obj in queryset[:1]:
	return obj

	async def alast(self):
	return await sync_to_async(self.last)()

	def in_bulk(self, id_list=None, *, field_name="pk"):
	"""
	Return a dictionary mapping each of the given IDs to the object with
	that ID. If `id_list` isn't provided, evaluate the entire QuerySet.
	"""
	if self.query.is_sliced:
	raise TypeError("Cannot use 'limit' or 'offset' with in_bulk().")
	if not issubclass(self._iterable_class, ModelIterable):
	raise TypeError("in_bulk() cannot be used with values() or values_list().")
	opts = self.model._meta
	unique_fields = [
	constraint.fields[0]
	for constraint in opts.total_unique_constraints
	if len(constraint.fields) == 1
	]
	if (
	field_name != "pk"
	and not opts.get_field(field_name).unique
	and field_name not in unique_fields
	and self.query.distinct_fields != (field_name,)
	):
	raise ValueError(
	"in_bulk()'s field_name must be a unique field but %r isn't."
	% field_name
	)
	if id_list is not None:
	if not id_list:
	return {}
	filter_key = "{}__in".format(field_name)
	id_list = tuple(id_list)
	batch_size = connections[self.db].ops.bulk_batch_size([opts.pk], id_list)
	# If the database has a limit on the number of query parameters
	# (e.g. SQLite), retrieve objects in batches if necessary.
	if batch_size and batch_size < len(id_list):
	qs = ()
	for offset in range(0, len(id_list), batch_size):
	batch = id_list[offset : offset + batch_size]
	qs += tuple(self.filter(**{filter_key: batch}))
	else:
	qs = self.filter(**{filter_key: id_list})
	else:
	qs = self._chain()
	return {getattr(obj, field_name): obj for obj in qs}

	async def ain_bulk(self, id_list=None, *, field_name="pk"):
	return await sync_to_async(self.in_bulk)(
	id_list=id_list,
	field_name=field_name,
	)

	def delete(self):
	"""Delete the records in the current QuerySet."""
	self._not_support_combined_queries("delete")
	if self.query.is_sliced:
	raise TypeError("Cannot use 'limit' or 'offset' with delete().")
	if self.query.distinct_fields:
	raise TypeError("Cannot call delete() after .distinct(*fields).")
	if self._fields is not None:
	raise TypeError("Cannot call delete() after .values() or .values_list()")

	del_query = self._chain()

	# The delete is actually 2 queries - one to find related objects,
	# and one to delete. Make sure that the discovery of related
	# objects is performed on the same database as the deletion.
	del_query._for_write = True

	# Disable non-supported fields.
	del_query.query.select_for_update = False
	del_query.query.select_related = False
	del_query.query.clear_ordering(force=True)

	collector = Collector(using=del_query.db, origin=self)
	collector.collect(del_query)
	num_deleted, num_deleted_per_model = collector.delete()

	# Clear the result cache, in case this QuerySet gets reused.
	self._result_cache = None
	return num_deleted, num_deleted_per_model

	delete.alters_data = True
	delete.queryset_only = True

	async def adelete(self):
	return await sync_to_async(self.delete)()

	adelete.alters_data = True
	adelete.queryset_only = True

	def _raw_delete(self, using):
	"""
	Delete objects found from the given queryset in single direct SQL
	query. No signals are sent and there is no protection for cascades.
	"""
	query = self.query.clone()
	query.__class__ = sql.DeleteQuery
	return query.get_compiler(using).execute_sql(ROW_COUNT)

	_raw_delete.alters_data = True

	def update(self, **kwargs):
	"""
	Update all elements in the current QuerySet, setting all the given
	fields to the appropriate values.
	"""
	self._not_support_combined_queries("update")
	if self.query.is_sliced:
	raise TypeError("Cannot update a query once a slice has been taken.")
	self._for_write = True
	query = self.query.chain(sql.UpdateQuery)
	query.add_update_values(kwargs)

	# Inline annotations in order_by(), if possible.
	new_order_by = []
	for col in query.order_by:
	alias = col
	descending = False
	if isinstance(alias, str) and alias.startswith("-"):
	alias = alias.removeprefix("-")
	descending = True
	if annotation := query.annotations.get(alias):
	if getattr(annotation, "contains_aggregate", False):
	raise exceptions.FieldError(
	f"Cannot update when ordering by an aggregate: {annotation}"
	)
	if descending:
	annotation = annotation.desc()
	new_order_by.append(annotation)
	else:
	new_order_by.append(col)
	query.order_by = tuple(new_order_by)

	# Clear SELECT clause as all annotation references were inlined by
	# add_update_values() already.
	query.clear_select_clause()
	with transaction.mark_for_rollback_on_error(using=self.db):
	rows = query.get_compiler(self.db).execute_sql(ROW_COUNT)
	self._result_cache = None
	return rows

	update.alters_data = True

	async def aupdate(self, **kwargs):
	return await sync_to_async(self.update)(**kwargs)

	aupdate.alters_data = True

	def _update(self, values, returning_fields=None):
	"""
	A version of update() that accepts field objects instead of field
	names. Used primarily for model saving and not intended for use by
	general code (it requires too much poking around at model internals to
	be useful at that level).
	"""
	if self.query.is_sliced:
	raise TypeError("Cannot update a query once a slice has been taken.")
	query = self.query.chain(sql.UpdateQuery)
	query.add_update_fields(values)
	# Clear any annotations so that they won't be present in subqueries.
	query.annotations = {}
	self._result_cache = None
	if returning_fields is None:
	return query.get_compiler(self.db).execute_sql(ROW_COUNT)
	return query.get_compiler(self.db).execute_returning_sql(returning_fields)

	_update.alters_data = True
	_update.queryset_only = False

	def exists(self):
	"""
	Return True if the QuerySet would have any results, False otherwise.
	"""
	if self._result_cache is None:
	return self.query.has_results(using=self.db)
	return bool(self._result_cache)

	async def aexists(self):
	return await sync_to_async(self.exists)()

	def contains(self, obj):
	"""
	Return True if the QuerySet contains the provided obj,
	False otherwise.
	"""
	self._not_support_combined_queries("contains")
	if self._fields is not None:
	raise TypeError(
	"Cannot call QuerySet.contains() after .values() or .values_list()."
	)
	try:
	if obj._meta.concrete_model != self.model._meta.concrete_model:
	return False
	except AttributeError:
	raise TypeError("'obj' must be a model instance.")
	if not obj._is_pk_set():
	raise ValueError("QuerySet.contains() cannot be used on unsaved objects.")
	if self._result_cache is not None:
	return obj in self._result_cache
	return self.filter(pk=obj.pk).exists()

	async def acontains(self, obj):
	return await sync_to_async(self.contains)(obj=obj)

	def _prefetch_related_objects(self):
	# This method can only be called once the result cache has been filled.
	prefetch_related_objects(self._result_cache, *self._prefetch_related_lookups)
	self._prefetch_done = True

	def explain(self, , format=None, *options):
	"""
	Runs an EXPLAIN on the SQL query this QuerySet would perform, and
	returns the results.
	"""
	return self.query.explain(using=self.db, format=format, **options)

	async def aexplain(self, , format=None, *options):
	return await sync_to_async(self.explain)(format=format, **options)

	##################################################
	# PUBLIC METHODS THAT RETURN A QUERYSET SUBCLASS #
	##################################################

	def raw(self, raw_query, params=(), translations=None, using=None):
	if using is None:
	using = self.db
	qs = RawQuerySet(
	raw_query,
	model=self.model,
	params=params,
	translations=translations,
	using=using,
	)
	qs._prefetch_related_lookups = self._prefetch_related_lookups[:]
	return qs

	def _values(self, fields, *expressions):
	clone = self._chain()
	if expressions:
	# RemovedInDjango70Warning: When the deprecation ends, deindent as:
	# clone = clone.annotate(**expressions)
	with warnings.catch_warnings(
	action="ignore", category=RemovedInDjango70Warning
	):
	clone = clone.annotate(**expressions)
	clone._fields = fields
	clone.query.set_values(fields)
	return clone

	def values(self, fields, *expressions):
	fields += tuple(expressions)
	clone = self._values(fields, *expressions)
	clone._iterable_class = ValuesIterable
	return clone

	def values_list(self, *fields, flat=False, named=False):
	if flat and named:
	raise TypeError("'flat' and 'named' can't be used together.")
	if flat:
	if len(fields) > 1:
	raise TypeError(
	"'flat' is not valid when values_list is called with more than one "
	"field."
	)
	elif not fields:
	fields = [self.model._meta.concrete_fields[0].attname]

	field_names = {f: False for f in fields if not hasattr(f, "resolve_expression")}
	_fields = []
	expressions = {}
	counter = 1
	for field in fields:
	field_name = field
	expression = None
	if hasattr(field, "resolve_expression"):
	field_name = getattr(
	field, "default_alias", field.__class__.__name__.lower()
	)
	expression = field
	# For backward compatibility reasons expressions are always
	# prefixed with the counter even if their default alias doesn't
	# collide with field names. Changing this logic could break
	# some usage of named=True.
	seen = True
	elif seen := field_names[field_name]:
	expression = F(field_name)
	if seen:
	field_name_prefix = field_name
	while (field_name := f"{field_name_prefix}{counter}") in field_names:
	counter += 1
	if expression is not None:
	expressions[field_name] = expression
	field_names[field_name] = True
	_fields.append(field_name)

	clone = self._values(_fields, *expressions)
	clone._iterable_class = (
	NamedValuesListIterable
	if named
	else FlatValuesListIterable if flat else ValuesListIterable
	)
	return clone

	def dates(self, field_name, kind, order="ASC"):
	"""
	Return a list of date objects representing all available dates for
	the given field_name, scoped to 'kind'.
	"""
	if kind not in ("year", "month", "week", "day"):
	raise ValueError("'kind' must be one of 'year', 'month', 'week', or 'day'.")
	if order not in ("ASC", "DESC"):
	raise ValueError("'order' must be either 'ASC' or 'DESC'.")
	return (
	self.annotate(
	datefield=Trunc(field_name, kind, output_field=DateField()),
	plain_field=F(field_name),
	)
	.values_list("datefield", flat=True)
	.distinct()
	.filter(plain_field__isnull=False)
	.order_by(("-" if order == "DESC" else "") + "datefield")
	)

	def datetimes(self, field_name, kind, order="ASC", tzinfo=None):
	"""
	Return a list of datetime objects representing all available
	datetimes for the given field_name, scoped to 'kind'.
	"""
	if kind not in ("year", "month", "week", "day", "hour", "minute", "second"):
	raise ValueError(
	"'kind' must be one of 'year', 'month', 'week', 'day', "
	"'hour', 'minute', or 'second'."
	)
	if order not in ("ASC", "DESC"):
	raise ValueError("'order' must be either 'ASC' or 'DESC'.")
	if settings.USE_TZ:
	if tzinfo is None:
	tzinfo = timezone.get_current_timezone()
	else:
	tzinfo = None
	return (
	self.annotate(
	datetimefield=Trunc(
	field_name,
	kind,
	output_field=DateTimeField(),
	tzinfo=tzinfo,
	),
	plain_field=F(field_name),
	)
	.values_list("datetimefield", flat=True)
	.distinct()
	.filter(plain_field__isnull=False)
	.order_by(("-" if order == "DESC" else "") + "datetimefield")
	)

	def none(self):
	"""Return an empty QuerySet."""
	clone = self._chain()
	clone.query.set_empty()
	return clone

	##################################################################
	# PUBLIC METHODS THAT ALTER ATTRIBUTES AND RETURN A NEW QUERYSET #
	##################################################################

	def all(self):
	"""
	Return a new QuerySet that is a copy of the current one. This allows a
	QuerySet to proxy for a model manager in some cases.
	"""
	return self._chain()

	def filter(self, args, *kwargs):
	"""
	Return a new QuerySet instance with the args ANDed to the existing
	set.
	"""
	self._not_support_combined_queries("filter")
	return self._filter_or_exclude(False, args, kwargs)

	def exclude(self, args, *kwargs):
	"""
	Return a new QuerySet instance with NOT (args) ANDed to the existing
	set.
	"""
	self._not_support_combined_queries("exclude")
	return self._filter_or_exclude(True, args, kwargs)

	def _filter_or_exclude(self, negate, args, kwargs):
	if (args or kwargs) and self.query.is_sliced:
	raise TypeError("Cannot filter a query once a slice has been taken.")
	clone = self._chain()
	if self._defer_next_filter:
	self._defer_next_filter = False
	clone._deferred_filter = negate, args, kwargs
	else:
	clone._filter_or_exclude_inplace(negate, args, kwargs)
	return clone

	def _filter_or_exclude_inplace(self, negate, args, kwargs):
	if invalid_kwargs := PROHIBITED_FILTER_KWARGS.intersection(kwargs):
	invalid_kwargs_str = ", ".join(f"'{k}'" for k in sorted(invalid_kwargs))
	raise TypeError(f"The following kwargs are invalid: {invalid_kwargs_str}")
	if negate:
	self._query.add_q(~Q(args, *kwargs))
	else:
	self._query.add_q(Q(args, *kwargs))

	def complex_filter(self, filter_obj):
	"""
	Return a new QuerySet instance with filter_obj added to the filters.

	filter_obj can be a Q object or a dictionary of keyword lookup
	arguments.

	This exists to support framework features such as 'limit_choices_to',
	and usually it will be more natural to use other methods.
	"""
	if isinstance(filter_obj, Q):
	clone = self._chain()
	clone.query.add_q(filter_obj)
	return clone
	else:
	return self._filter_or_exclude(False, args=(), kwargs=filter_obj)

	def _combinator_query(self, combinator, *other_qs, all=False):
	# Clone the query to inherit the select list and everything
	clone = self._chain()
	# Clear limits and ordering so they can be reapplied
	clone.query.clear_ordering(force=True)
	clone.query.clear_limits()
	clone.query.combined_queries = (self.query, *(qs.query for qs in other_qs))
	clone.query.combinator = combinator
	clone.query.combinator_all = all
	return clone

	def union(self, *other_qs, all=False):
	# If the query is an EmptyQuerySet, combine all nonempty querysets.
	if isinstance(self, EmptyQuerySet):
	qs = [q for q in other_qs if not isinstance(q, EmptyQuerySet)]
	if not qs:
	return self
	if len(qs) == 1:
	return qs[0]
	return qs[0]._combinator_query("union", *qs[1:], all=all)
	elif not other_qs:
	return self
	return self._combinator_query("union", *other_qs, all=all)

	def intersection(self, *other_qs):
	# If any query is an EmptyQuerySet, return it.
	if isinstance(self, EmptyQuerySet):
	return self
	for other in other_qs:
	if isinstance(other, EmptyQuerySet):
	return other
	return self._combinator_query("intersection", *other_qs)

	def difference(self, *other_qs):
	# If the query is an EmptyQuerySet, return it.
	if isinstance(self, EmptyQuerySet):
	return self
	return self._combinator_query("difference", *other_qs)

	def select_for_update(self, nowait=False, skip_locked=False, of=(), no_key=False):
	"""
	Return a new QuerySet instance that will select objects with a
	FOR UPDATE lock.
	"""
	if nowait and skip_locked:
	raise ValueError("The nowait option cannot be used with skip_locked.")
	obj = self._chain()
	obj._for_write = True
	obj.query.select_for_update = True
	obj.query.select_for_update_nowait = nowait
	obj.query.select_for_update_skip_locked = skip_locked
	obj.query.select_for_update_of = of
	obj.query.select_for_no_key_update = no_key
	return obj

	def select_related(self, *fields):
	"""
	Return a new QuerySet instance that will select related objects.

	If fields are specified, they must be ForeignKey fields and only those
	related objects are included in the selection.

	If select_related(None) is called, clear the list.
	"""
	self._not_support_combined_queries("select_related")
	if self._fields is not None:
	raise TypeError(
	"Cannot call select_related() after .values() or .values_list()"
	)

	obj = self._chain()
	if fields == (None,):
	obj.query.select_related = False
	elif fields:
	obj.query.add_select_related(fields)
	else:
	obj.query.select_related = True
	return obj

	def prefetch_related(self, *lookups):
	"""
	Return a new QuerySet instance that will prefetch the specified
	Many-To-One and Many-To-Many related objects when the QuerySet is
	evaluated.

	When prefetch_related() is called more than once, append to the list of
	prefetch lookups. If prefetch_related(None) is called, clear the list.
	"""
	self._not_support_combined_queries("prefetch_related")
	clone = self._chain()
	if lookups == (None,):
	clone._prefetch_related_lookups = ()
	else:
	for lookup in lookups:
	if isinstance(lookup, Prefetch):
	lookup = lookup.prefetch_to
	lookup = lookup.split(LOOKUP_SEP, 1)[0]
	if lookup in self.query._filtered_relations:
	raise ValueError(
	"prefetch_related() is not supported with FilteredRelation."
	)
	clone._prefetch_related_lookups = clone._prefetch_related_lookups + lookups
	return clone

	def annotate(self, args, *kwargs):
	"""
	Return a query set in which the returned objects have been annotated
	with extra data or aggregations.
	"""
	self._not_support_combined_queries("annotate")
	return self._annotate(args, kwargs, select=True)

	def alias(self, args, *kwargs):
	"""
	Return a query set with added aliases for extra data or aggregations.
	"""
	self._not_support_combined_queries("alias")
	return self._annotate(args, kwargs, select=False)

	def _annotate(self, args, kwargs, select=True):
	self._validate_values_are_expressions(
	args + tuple(kwargs.values()), method_name="annotate"
	)
	annotations = {}
	for arg in args:
	# The default_alias property raises TypeError if default_alias
	# can't be set automatically or AttributeError if it isn't an
	# attribute.
	try:
	if arg.default_alias in kwargs:
	raise ValueError(
	"The named annotation '%s' conflicts with the "
	"default name for another annotation." % arg.default_alias
	)
	except (TypeError, AttributeError):
	raise TypeError("Complex annotations require an alias")
	annotations[arg.default_alias] = arg
	annotations.update(kwargs)

	clone = self._chain()
	names = self._fields
	if names is None:
	names = set(
	chain.from_iterable(
	(
	(field.name, field.attname)
	if hasattr(field, "attname")
	else (field.name,)
	)
	for field in self.model._meta.get_fields()
	)
	)

	for alias, annotation in annotations.items():
	if alias in names:
	raise ValueError(
	"The annotation '%s' conflicts with a field on "
	"the model." % alias
	)
	if isinstance(annotation, FilteredRelation):
	clone.query.add_filtered_relation(annotation, alias)
	else:
	clone.query.add_annotation(
	annotation,
	alias,
	select=select,
	)
	for alias, annotation in clone.query.annotations.items():
	if alias in annotations and annotation.contains_aggregate:
	if clone._fields is None:
	clone.query.group_by = True
	else:
	clone.query.set_group_by()
	break

	return clone

	def order_by(self, *field_names):
	"""Return a new QuerySet instance with the ordering changed."""
	if self.query.is_sliced:
	raise TypeError("Cannot reorder a query once a slice has been taken.")
	obj = self._chain()
	obj.query.clear_ordering(force=True, clear_default=False)
	obj.query.add_ordering(*field_names)
	return obj

	def distinct(self, *field_names):
	"""
	Return a new QuerySet instance that will select only distinct results.
	"""
	self._not_support_combined_queries("distinct")
	if self.query.is_sliced:
	raise TypeError(
	"Cannot create distinct fields once a slice has been taken."
	)
	obj = self._chain()
	obj.query.add_distinct_fields(*field_names)
	return obj

	def extra(
	self,
	select=None,
	where=None,
	params=None,
	tables=None,
	order_by=None,
	select_params=None,
	):
	"""Add extra SQL fragments to the query."""
	self._not_support_combined_queries("extra")
	if self.query.is_sliced:
	raise TypeError("Cannot change a query once a slice has been taken.")
	clone = self._chain()
	clone.query.add_extra(select, select_params, where, params, tables, order_by)
	return clone

	def reverse(self):
	"""Reverse the ordering of the QuerySet."""
	if self.query.is_sliced:
	raise TypeError("Cannot reverse a query once a slice has been taken.")
	clone = self._chain()
	clone.query.standard_ordering = not clone.query.standard_ordering
	return clone

	def defer(self, *fields):
	"""
	Defer the loading of data for certain fields until they are accessed.
	Add the set of deferred fields to any existing set of deferred fields.
	The only exception to this is if None is passed in as the only
	parameter, in which case remove all deferrals.
	"""
	self._not_support_combined_queries("defer")
	if self._fields is not None:
	raise TypeError("Cannot call defer() after .values() or .values_list()")
	clone = self._chain()
	if fields == (None,):
	clone.query.clear_deferred_loading()
	else:
	clone.query.add_deferred_loading(fields)
	return clone

	def only(self, *fields):
	"""
	Essentially, the opposite of defer(). Only the fields passed into this
	method and that are not already specified as deferred are loaded
	immediately when the queryset is evaluated.
	"""
	self._not_support_combined_queries("only")
	if self._fields is not None:
	raise TypeError("Cannot call only() after .values() or .values_list()")
	if fields == (None,):
	# Can only pass None to defer(), not only(), as the rest option.
	# That won't stop people trying to do this, so let's be explicit.
	raise TypeError("Cannot pass None as an argument to only().")
	for field in fields:
	field = field.split(LOOKUP_SEP, 1)[0]
	if field in self.query._filtered_relations:
	raise ValueError("only() is not supported with FilteredRelation.")
	clone = self._chain()
	clone.query.add_immediate_loading(fields)
	return clone

	def using(self, alias):
	"""Select which database this QuerySet should execute against."""
	clone = self._chain()
	clone._db = alias
	return clone

	###################################
	# PUBLIC INTROSPECTION ATTRIBUTES #
	###################################

	@property
	def ordered(self):
	"""
	Return True if the QuerySet is ordered -- i.e. has an order_by()
	clause or a default ordering on the model (or is empty).
	"""
	if isinstance(self, EmptyQuerySet):
	return True
	if self.query.extra_order_by or self.query.order_by:
	return True
	elif (
	self.query.default_ordering
	and self.query.get_meta().ordering
	and
	# A default ordering doesn't affect GROUP BY queries.
	not self.query.group_by
	):
	return True
	else:
	return False

	@property
	def db(self):
	"""Return the database used if this query is executed now."""
	if self._for_write:
	return self._db or router.db_for_write(self.model, **self._hints)
	return self._db or router.db_for_read(self.model, **self._hints)

	###################
	# PRIVATE METHODS #
	###################

	def _insert(
	self,
	objs,
	fields,
	returning_fields=None,
	raw=False,
	using=None,
	on_conflict=None,
	update_fields=None,
	unique_fields=None,
	):
	"""
	Insert a new record for the given model. This provides an interface to
	the InsertQuery class and is how Model.save() is implemented.
	"""
	self._for_write = True
	if using is None:
	using = self.db
	query = sql.InsertQuery(
	self.model,
	on_conflict=on_conflict,
	update_fields=update_fields,
	unique_fields=unique_fields,
	)
	query.insert_values(fields, objs, raw=raw)
	return query.get_compiler(using=using).execute_sql(returning_fields)

	_insert.alters_data = True
	_insert.queryset_only = False

	def _batched_insert(
	self,
	objs,
	fields,
	batch_size,
	on_conflict=None,
	update_fields=None,
	unique_fields=None,
	):
	"""
	Helper method for bulk_create() to insert objs one batch at a time.
	"""
	connection = connections[self.db]
	ops = connection.ops
	max_batch_size = max(ops.bulk_batch_size(fields, objs), 1)
	batch_size = min(batch_size, max_batch_size) if batch_size else max_batch_size
	inserted_rows = []
	returning_fields = (
	self.model._meta.db_returning_fields
	if (
	connection.features.can_return_rows_from_bulk_insert
	and (on_conflict is None or on_conflict == OnConflict.UPDATE)
	)
	else None
	)
	batches = [objs[i : i + batch_size] for i in range(0, len(objs), batch_size)]
	if len(batches) > 1:
	context = transaction.atomic(using=self.db, savepoint=False)
	else:
	context = nullcontext()
	with context:
	for item in batches:
	inserted_rows.extend(
	self._insert(
	item,
	fields=fields,
	using=self.db,
	on_conflict=on_conflict,
	update_fields=update_fields,
	unique_fields=unique_fields,
	returning_fields=returning_fields,
	)
	)
	return inserted_rows

	def _chain(self):
	"""
	Return a copy of the current QuerySet that's ready for another
	operation.
	"""
	obj = self._clone()
	if obj._sticky_filter:
	obj.query.filter_is_sticky = True
	obj._sticky_filter = False
	return obj

	def _clone(self):
	"""
	Return a copy of the current QuerySet. A lightweight alternative
	to deepcopy().
	"""
	c = self.__class__(
	model=self.model,
	query=self.query.chain(),
	using=self._db,
	hints=self._hints,
	)
	c._sticky_filter = self._sticky_filter
	c._for_write = self._for_write
	c._prefetch_related_lookups = self._prefetch_related_lookups[:]
	c._known_related_objects = self._known_related_objects
	c._iterable_class = self._iterable_class
	c._fields = self._fields
	return c

	def _fetch_all(self):
	if self._result_cache is None:
	self._result_cache = list(self._iterable_class(self))
	if self._prefetch_related_lookups and not self._prefetch_done:
	self._prefetch_related_objects()

	def _next_is_sticky(self):
	"""
	Indicate that the next filter call and the one following that should
	be treated as a single filter. This is only important when it comes to
	determining when to reuse tables for many-to-many filters. Required so
	that we can filter naturally on the results of related managers.

	This doesn't return a clone of the current QuerySet (it returns
	"self"). The method is only used internally and should be immediately
	followed by a filter() that does create a clone.
	"""
	self._sticky_filter = True
	return self

	def _merge_sanity_check(self, other):
	"""Check that two QuerySet classes may be merged."""
	if self._fields is not None and (
	set(self.query.values_select) != set(other.query.values_select)
	or set(self.query.extra_select) != set(other.query.extra_select)
	or set(self.query.annotation_select) != set(other.query.annotation_select)
	):
	raise TypeError(
	"Merging '%s' classes must involve the same values in each case."
	% self.__class__.__name__
	)

	def _merge_known_related_objects(self, other):
	"""
	Keep track of all known related objects from either QuerySet instance.
	"""
	for field, objects in other._known_related_objects.items():
	self._known_related_objects.setdefault(field, {}).update(objects)

	def resolve_expression(self, args, *kwargs):
	query = self.query.resolve_expression(args, *kwargs)
	query._db = self._db
	return query

	resolve_expression.queryset_only = True

	def _add_hints(self, **hints):
	"""
	Update hinting information for use by routers. Add new key/values or
	overwrite existing key/values.
	"""
	self._hints.update(hints)

	def _has_filters(self):
	"""
	Check if this QuerySet has any filtering going on. This isn't
	equivalent with checking if all objects are present in results, for
	example, qs[1:]._has_filters() -> False.
	"""
	return self.query.has_filters()

	@staticmethod
	def _validate_values_are_expressions(values, method_name):
	invalid_args = sorted(
	str(arg) for arg in values if not hasattr(arg, "resolve_expression")
	)
	if invalid_args:
	raise TypeError(
	"QuerySet.%s() received non-expression(s): %s."
	% (
	method_name,
	", ".join(invalid_args),
	)
	)

	def _not_support_combined_queries(self, operation_name):
	if self.query.combinator:
	raise NotSupportedError(
	"Calling QuerySet.%s() after %s() is not supported."
	% (operation_name, self.query.combinator)
	)

	def _check_operator_queryset(self, other, operator_):
	if self.query.combinator or other.query.combinator:
	raise TypeError(f"Cannot use {operator_} operator with combined queryset.")

	def _check_ordering_first_last_queryset_aggregation(self, method):
	if (
	isinstance(self.query.group_by, tuple)
	# Raise if the pk fields are not in the group_by.
	and self.model._meta.pk
	not in {col.output_field for col in self.query.group_by}
	and set(self.model._meta.pk_fields).difference(
	{col.target for col in self.query.group_by}
	)
	):
	raise TypeError(
	f"Cannot use QuerySet.{method}() on an unordered queryset performing "
	f"aggregation. Add an ordering with order_by()."
	)


	class InstanceCheckMeta(type):
	def __instancecheck__(self, instance):
	return isinstance(instance, QuerySet) and instance.query.is_empty()


	class EmptyQuerySet(metaclass=InstanceCheckMeta):
	"""
	Marker class to checking if a queryset is empty by .none():
	isinstance(qs.none(), EmptyQuerySet) -> True
	"""

	def __init__(self, args, *kwargs):
	raise TypeError("EmptyQuerySet can't be instantiated")


	class RawQuerySet:
	"""
	Provide an iterator which converts the results of raw SQL queries into
	annotated model instances.
	"""

	def __init__(
	self,
	raw_query,
	model=None,
	query=None,
	params=(),
	translations=None,
	using=None,
	hints=None,
	):
	self.raw_query = raw_query
	self.model = model
	self._db = using
	self._hints = hints or {}
	self.query = query or sql.RawQuery(sql=raw_query, using=self.db, params=params)
	self.params = params
	self.translations = translations or {}
	self._result_cache = None
	self._prefetch_related_lookups = ()
	self._prefetch_done = False

	def resolve_model_init_order(self):
	"""Resolve the init field names and value positions."""
	converter = connections[self.db].introspection.identifier_converter
	model_init_fields = [
	field
	for column_name, field in self.model_fields.items()
	if column_name in self.columns
	]
	annotation_fields = [
	(column, pos)
	for pos, column in enumerate(self.columns)
	if column not in self.model_fields
	]
	model_init_order = [
	self.columns.index(converter(f.column)) for f in model_init_fields
	]
	model_init_names = [f.attname for f in model_init_fields]
	return model_init_names, model_init_order, annotation_fields

	def prefetch_related(self, *lookups):
	"""Same as QuerySet.prefetch_related()"""
	clone = self._clone()
	if lookups == (None,):
	clone._prefetch_related_lookups = ()
	else:
	clone._prefetch_related_lookups = clone._prefetch_related_lookups + lookups
	return clone

	def _prefetch_related_objects(self):
	prefetch_related_objects(self._result_cache, *self._prefetch_related_lookups)
	self._prefetch_done = True

	def _clone(self):
	"""Same as QuerySet._clone()"""
	c = self.__class__(
	self.raw_query,
	model=self.model,
	query=self.query,
	params=self.params,
	translations=self.translations,
	using=self._db,
	hints=self._hints,
	)
	c._prefetch_related_lookups = self._prefetch_related_lookups[:]
	return c

	def _fetch_all(self):
	if self._result_cache is None:
	self._result_cache = list(self.iterator())
	if self._prefetch_related_lookups and not self._prefetch_done:
	self._prefetch_related_objects()

	def __len__(self):
	self._fetch_all()
	return len(self._result_cache)

	def __bool__(self):
	self._fetch_all()
	return bool(self._result_cache)

	def __iter__(self):
	self._fetch_all()
	return iter(self._result_cache)

	def __aiter__(self):
	# Remember, __aiter__ itself is synchronous, it's the thing it returns
	# that is async!
	async def generator():
	await sync_to_async(self._fetch_all)()
	for item in self._result_cache:
	yield item

	return generator()

	def iterator(self):
	yield from RawModelIterable(self)

	def __repr__(self):
	return "<%s: %s>" % (self.__class__.__name__, self.query)

	def __getitem__(self, k):
	return list(self)[k]

	@property
	def db(self):
	"""Return the database used if this query is executed now."""
	return self._db or router.db_for_read(self.model, **self._hints)

	def using(self, alias):
	"""Select the database this RawQuerySet should execute against."""
	return RawQuerySet(
	self.raw_query,
	model=self.model,
	query=self.query.chain(using=alias),
	params=self.params,
	translations=self.translations,
	using=alias,
	)

	@cached_property
	def columns(self):
	"""
	A list of model field names in the order they'll appear in the
	query results.
	"""
	columns = self.query.get_columns()
	# Adjust any column names which don't match field names
	for query_name, model_name in self.translations.items():
	# Ignore translations for nonexistent column names
	try:
	index = columns.index(query_name)
	except ValueError:
	pass
	else:
	columns[index] = model_name
	return columns

	@cached_property
	def model_fields(self):
	"""A dict mapping column names to model field names."""
	converter = connections[self.db].introspection.identifier_converter
	return {
	converter(field.column): field
	for field in self.model._meta.fields
	# Fields with None "column" should be ignored
	# (e.g. CompositePrimaryKey).
	if field.column
	}


	class Prefetch:
	def __init__(self, lookup, queryset=None, to_attr=None):
	# `prefetch_through` is the path we traverse to perform the prefetch.
	self.prefetch_through = lookup
	# `prefetch_to` is the path to the attribute that stores the result.
	self.prefetch_to = lookup
	if queryset is not None and (
	isinstance(queryset, RawQuerySet)
	or (
	hasattr(queryset, "_iterable_class")
	and not issubclass(queryset._iterable_class, ModelIterable)
	)
	):
	raise ValueError(
	"Prefetch querysets cannot use raw(), values(), and values_list()."
	)
	if to_attr:
	self.prefetch_to = LOOKUP_SEP.join(
	lookup.split(LOOKUP_SEP)[:-1] + [to_attr]
	)

	self.queryset = queryset
	self.to_attr = to_attr

	def __getstate__(self):
	obj_dict = self.__dict__.copy()
	if self.queryset is not None:
	queryset = self.queryset._chain()
	# Prevent the QuerySet from being evaluated
	queryset._result_cache = []
	queryset._prefetch_done = True
	obj_dict["queryset"] = queryset
	return obj_dict

	def add_prefix(self, prefix):
	self.prefetch_through = prefix + LOOKUP_SEP + self.prefetch_through
	self.prefetch_to = prefix + LOOKUP_SEP + self.prefetch_to

	def get_current_prefetch_to(self, level):
	return LOOKUP_SEP.join(self.prefetch_to.split(LOOKUP_SEP)[: level + 1])

	def get_current_to_attr(self, level):
	parts = self.prefetch_to.split(LOOKUP_SEP)
	to_attr = parts[level]
	as_attr = self.to_attr and level == len(parts) - 1
	return to_attr, as_attr

	def get_current_querysets(self, level):
	if (
	self.get_current_prefetch_to(level) == self.prefetch_to
	and self.queryset is not None
	):
	return [self.queryset]
	return None

	def __eq__(self, other):
	if not isinstance(other, Prefetch):
	return NotImplemented
	return self.prefetch_to == other.prefetch_to

	def __hash__(self):
	return hash((self.__class__, self.prefetch_to))


	def normalize_prefetch_lookups(lookups, prefix=None):
	"""Normalize lookups into Prefetch objects."""
	ret = []
	for lookup in lookups:
	if not isinstance(lookup, Prefetch):
	lookup = Prefetch(lookup)
	if prefix:
	lookup.add_prefix(prefix)
	ret.append(lookup)
	return ret


	def prefetch_related_objects(model_instances, *related_lookups):
	"""
	Populate prefetched object caches for an iterable of model instances based
	on the lookups/Prefetch instances given.
	"""
	if not model_instances:
	return # nothing to do

	# We need to be able to dynamically add to the list of prefetch_related
	# lookups that we look up (see below). So we need some book keeping to
	# ensure we don't do duplicate work.
	done_queries = {} # dictionary of things like 'foo__bar': [results]

	auto_lookups = set() # we add to this as we go through.
	followed_descriptors = set() # recursion protection

	all_lookups = normalize_prefetch_lookups(reversed(related_lookups))
	while all_lookups:
	lookup = all_lookups.pop()
	if lookup.prefetch_to in done_queries:
	if lookup.queryset is not None:
	raise ValueError(
	"'%s' lookup was already seen with a different queryset. "
	"You may need to adjust the ordering of your lookups."
	% lookup.prefetch_to
	)

	continue

	# Top level, the list of objects to decorate is the result cache
	# from the primary QuerySet. It won't be for deeper levels.
	obj_list = model_instances

	through_attrs = lookup.prefetch_through.split(LOOKUP_SEP)
	for level, through_attr in enumerate(through_attrs):
	# Prepare main instances
	if not obj_list:
	break

	prefetch_to = lookup.get_current_prefetch_to(level)
	if prefetch_to in done_queries:
	# Skip any prefetching, and any object preparation
	obj_list = done_queries[prefetch_to]
	continue

	# Prepare objects:
	good_objects = True
	for obj in obj_list:
	# Since prefetching can re-use instances, it is possible to
	# have the same instance multiple times in obj_list, so obj
	# might already be prepared.
	if not hasattr(obj, "_prefetched_objects_cache"):
	try:
	obj._prefetched_objects_cache = {}
	except (AttributeError, TypeError):
	# Must be an immutable object from
	# values_list(flat=True), for example (TypeError) or
	# a QuerySet subclass that isn't returning Model
	# instances (AttributeError), either in Django or a 3rd
	# party. prefetch_related() doesn't make sense, so
	# quit.
	good_objects = False
	break
	if not good_objects:
	break

	# Descend down tree

	# We assume that objects retrieved are homogeneous (which is the
	# premise of prefetch_related), so what applies to first object
	# applies to all.
	first_obj = next(iter(obj_list))
	to_attr = lookup.get_current_to_attr(level)[0]
	prefetcher, descriptor, attr_found, is_fetched = get_prefetcher(
	first_obj, through_attr, to_attr
	)

	if not attr_found:
	raise AttributeError(
	"Cannot find '%s' on %s object, '%s' is an invalid "
	"parameter to prefetch_related()"
	% (
	through_attr,
	first_obj.__class__.__name__,
	lookup.prefetch_through,
	)
	)

	if level == len(through_attrs) - 1 and prefetcher is None:
	# Last one, this must resolve to something that supports
	# prefetching, otherwise there is no point adding it and the
	# developer asking for it has made a mistake.
	raise ValueError(
	"'%s' does not resolve to an item that supports "
	"prefetching - this is an invalid parameter to "
	"prefetch_related()." % lookup.prefetch_through
	)

	obj_to_fetch = None
	if prefetcher is not None:
	obj_to_fetch = [obj for obj in obj_list if not is_fetched(obj)]

	if obj_to_fetch:
	obj_list, additional_lookups = prefetch_one_level(
	obj_to_fetch,
	prefetcher,
	lookup,
	level,
	)
	# We need to ensure we don't keep adding lookups from the
	# same relationships to stop infinite recursion. So, if we
	# are already on an automatically added lookup, don't add
	# the new lookups from relationships we've seen already.
	if not (
	prefetch_to in done_queries
	and lookup in auto_lookups
	and descriptor in followed_descriptors
	):
	done_queries[prefetch_to] = obj_list
	new_lookups = normalize_prefetch_lookups(
	reversed(additional_lookups), prefetch_to
	)
	auto_lookups.update(new_lookups)
	all_lookups.extend(new_lookups)
	followed_descriptors.add(descriptor)
	else:
	# Either a singly related object that has already been fetched
	# (e.g. via select_related), or hopefully some other property
	# that doesn't support prefetching but needs to be traversed.

	# We replace the current list of parent objects with the list
	# of related objects, filtering out empty or missing values so
	# that we can continue with nullable or reverse relations.
	new_obj_list = []
	for obj in obj_list:
	if through_attr in getattr(obj, "_prefetched_objects_cache", ()):
	# If related objects have been prefetched, use the
	# cache rather than the object's through_attr.
	new_obj = list(obj._prefetched_objects_cache.get(through_attr))
	else:
	try:
	new_obj = getattr(obj, through_attr)
	except exceptions.ObjectDoesNotExist:
	continue
	if new_obj is None:
	continue
	# We special-case `list` rather than something more generic
	# like `Iterable` because we don't want to accidentally
	# match user models that define __iter__.
	if isinstance(new_obj, list):
	new_obj_list.extend(new_obj)
	else:
	new_obj_list.append(new_obj)
	obj_list = new_obj_list


	async def aprefetch_related_objects(model_instances, *related_lookups):
	"""See prefetch_related_objects()."""
	return await sync_to_async(prefetch_related_objects)(
	model_instances, *related_lookups
	)


	def get_prefetcher(instance, through_attr, to_attr):
	"""
	For the attribute 'through_attr' on the given instance, find
	an object that has a get_prefetch_querysets().
	Return a 4 tuple containing:
	(the object with get_prefetch_querysets (or None),
	the descriptor object representing this relationship (or None),
	a boolean that is False if the attribute was not found at all,
	a function that takes an instance and returns a boolean that is True if
	the attribute has already been fetched for that instance)
	"""

	def is_to_attr_fetched(model, to_attr):
	# Special case cached_property instances because hasattr() triggers
	# attribute computation and assignment.
	if isinstance(getattr(model, to_attr, None), cached_property):

	def has_cached_property(instance):
	return to_attr in instance.__dict__

	return has_cached_property

	def has_to_attr_attribute(instance):
	return hasattr(instance, to_attr)

	return has_to_attr_attribute

	prefetcher = None
	is_fetched = is_to_attr_fetched(instance.__class__, to_attr)

	# For singly related objects, we have to avoid getting the attribute
	# from the object, as this will trigger the query. So we first try
	# on the class, in order to get the descriptor object.
	rel_obj_descriptor = getattr(instance.__class__, through_attr, None)
	if rel_obj_descriptor is None:
	attr_found = hasattr(instance, through_attr)
	else:
	attr_found = True
	if rel_obj_descriptor:
	# singly related object, descriptor object has the
	# get_prefetch_querysets() method.
	if hasattr(rel_obj_descriptor, "get_prefetch_querysets"):
	prefetcher = rel_obj_descriptor
	# If to_attr is set, check if the value has already been set,
	# which is done with has_to_attr_attribute(). Do not use the
	# method from the descriptor, as the cache_name it defines
	# checks the field name, not the to_attr value.
	if through_attr == to_attr:
	is_fetched = rel_obj_descriptor.is_cached
	else:
	# descriptor doesn't support prefetching, so we go ahead and
	# get the attribute on the instance rather than the class to
	# support many related managers
	rel_obj = getattr(instance, through_attr)
	if hasattr(rel_obj, "get_prefetch_querysets"):
	prefetcher = rel_obj
	if through_attr == to_attr:

	def in_prefetched_cache(instance):
	return through_attr in instance._prefetched_objects_cache

	is_fetched = in_prefetched_cache
	return prefetcher, rel_obj_descriptor, attr_found, is_fetched


	def prefetch_one_level(instances, prefetcher, lookup, level):
	"""
	Helper function for prefetch_related_objects().

	Run prefetches on all instances using the prefetcher object,
	assigning results to relevant caches in instance.

	Return the prefetched objects along with any additional prefetches that
	must be done due to prefetch_related lookups found from default managers.
	"""
	# prefetcher must have a method get_prefetch_querysets() which takes a list
	# of instances, and returns a tuple:

	# (queryset of instances of self.model that are related to passed in
	# instances,
	# callable that gets value to be matched for returned instances,
	# callable that gets value to be matched for passed in instances,
	# boolean that is True for singly related objects,
	# cache or field name to assign to,
	# boolean that is True when the previous argument is a cache name vs a
	# field name).

	# The 'values to be matched' must be hashable as they will be used
	# in a dictionary.
	(
	rel_qs,
	rel_obj_attr,
	instance_attr,
	single,
	cache_name,
	is_descriptor,
	) = prefetcher.get_prefetch_querysets(
	instances, lookup.get_current_querysets(level)
	)
	# We have to handle the possibility that the QuerySet we just got back
	# contains some prefetch_related lookups. We don't want to trigger the
	# prefetch_related functionality by evaluating the query. Rather, we need
	# to merge in the prefetch_related lookups.
	# Copy the lookups in case it is a Prefetch object which could be reused
	# later (happens in nested prefetch_related).
	additional_lookups = [
	copy.copy(additional_lookup)
	for additional_lookup in getattr(rel_qs, "_prefetch_related_lookups", ())
	]
	if additional_lookups:
	# Don't need to clone because the manager should have given us a fresh
	# instance, so we access an internal instead of using public interface
	# for performance reasons.
	rel_qs._prefetch_related_lookups = ()

	all_related_objects = list(rel_qs)

	rel_obj_cache = {}
	for rel_obj in all_related_objects:
	rel_attr_val = rel_obj_attr(rel_obj)
	rel_obj_cache.setdefault(rel_attr_val, []).append(rel_obj)

	to_attr, as_attr = lookup.get_current_to_attr(level)
	# Make sure `to_attr` does not conflict with a field.
	if as_attr and instances:
	# We assume that objects retrieved are homogeneous (which is the
	# premise of prefetch_related), so what applies to first object applies
	# to all.
	model = instances[0].__class__
	try:
	model._meta.get_field(to_attr)
	except exceptions.FieldDoesNotExist:
	pass
	else:
	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, [])

	if single:
	val = vals[0] if vals else None
	if as_attr:
	# A to_attr has been given for the prefetch.
	setattr(obj, to_attr, val)
	elif is_descriptor:
	# cache_name points to a field name in obj.
	# This field is a descriptor for a related object.
	setattr(obj, cache_name, val)
	else:
	# No to_attr has been given for this prefetch operation and the
	# cache_name does not point to a descriptor. Store the value of
	# the field in the object's field cache.
	obj._state.fields_cache[cache_name] = val
	else:
	if as_attr:
	setattr(obj, to_attr, vals)
	else:
	manager = getattr(obj, to_attr)
	if leaf and lookup.queryset is not None:
	qs = manager._apply_rel_filters(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.
	qs._prefetch_done = True
	obj._prefetched_objects_cache[cache_name] = qs
	return all_related_objects, additional_lookups


	class RelatedPopulator:
	"""
	RelatedPopulator is used for select_related() object instantiation.

	The idea is that each select_related() model will be populated by a
	different RelatedPopulator instance. The RelatedPopulator instances get
	klass_info and select (computed in SQLCompiler) plus the used db as
	input for initialization. That data is used to compute which columns
	to use, how to instantiate the model, and how to populate the links
	between the objects.

	The actual creation of the objects is done in populate() method. This
	method gets row and from_obj as input and populates the select_related()
	model instance.
	"""

	def __init__(self, klass_info, select, db):
	self.db = db
	# Pre-compute needed attributes. The attributes are:
	# - model_cls: the possibly deferred model class to instantiate
	# - either:
	# - cols_start, cols_end: usually the columns in the row are
	# in the same order model_cls.__init__ expects them, so we
	# can instantiate by model_cls(*row[cols_start:cols_end])
	# - reorder_for_init: When select_related descends to a child
	# class, then we want to reuse the already selected parent
	# data. However, in this case the parent data isn't necessarily
	# in the same order that Model.__init__ expects it to be, so
	# we have to reorder the parent data. The reorder_for_init
	# attribute contains a function used to reorder the field data
	# in the order __init__ expects it.
	# - pk_idx: the index of the primary key field in the reordered
	# model data. Used to check if a related object exists at all.
	# - init_list: the field attnames fetched from the database. For
	# deferred models this isn't the same as all attnames of the
	# model's fields.
	# - related_populators: a list of RelatedPopulator instances if
	# select_related() descends to related models from this model.
	# - local_setter, remote_setter: Methods to set cached values on
	# the object being populated and on the remote object. Usually
	# these are Field.set_cached_value() methods.
	select_fields = klass_info["select_fields"]
	from_parent = klass_info["from_parent"]
	if not from_parent:
	self.cols_start = select_fields[0]
	self.cols_end = select_fields[-1] + 1
	self.init_list = [
	f[0].target.attname for f in select[self.cols_start : self.cols_end]
	]
	self.reorder_for_init = None
	else:
	attname_indexes = {
	select[idx][0].target.attname: idx for idx in select_fields
	}
	model_init_attnames = (
	f.attname for f in klass_info["model"]._meta.concrete_fields
	)
	self.init_list = [
	attname for attname in model_init_attnames if attname in attname_indexes
	]
	self.reorder_for_init = operator.itemgetter(
	*[attname_indexes[attname] for attname in self.init_list]
	)

	self.model_cls = klass_info["model"]
	# A primary key must have all of its constituents not-NULL as
	# NULL != NULL and thus NULL cannot be referenced through a foreign
	# relationship. Therefore checking for a single member of the primary
	# key is enough to determine if the referenced object exists or not.
	self.pk_idx = self.init_list.index(self.model_cls._meta.pk_fields[0].attname)
	self.related_populators = get_related_populators(klass_info, select, self.db)
	self.local_setter = klass_info["local_setter"]
	self.remote_setter = klass_info["remote_setter"]

	def populate(self, row, from_obj):
	if self.reorder_for_init:
	obj_data = self.reorder_for_init(row)
	else:
	obj_data = row[self.cols_start : self.cols_end]
	if obj_data[self.pk_idx] is None:
	obj = None
	else:
	obj = self.model_cls.from_db(self.db, self.init_list, obj_data)
	for rel_iter in self.related_populators:
	rel_iter.populate(row, obj)
	self.local_setter(from_obj, obj)
	if obj is not None:
	self.remote_setter(obj, from_obj)


	def get_related_populators(klass_info, select, db):
	iterators = []
	related_klass_infos = klass_info.get("related_klass_infos", [])
	for rel_klass_info in related_klass_infos:
	rel_cls = RelatedPopulator(rel_klass_info, select, db)
	iterators.append(rel_cls)
	return iterators

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