"""
The main QuerySet implementation. This provides the public API for the ORM.
"""
from copy import deepcopy
from itertools import izip
from django.db import connections,router,transaction,IntegrityError
from django.db.models.aggregates import Aggregate
from django.db.models.fields import DateField
from django.db.models.query_utils import Q,select_related_descend,CollectedObjects,CyclicDependency,deferred_class_factory,InvalidQuery
from django.db.models import signals,sql
from django.utils.copycompat import deepcopy
# Used to control how many objects are worked with at once in some cases (e.g.
# when deleting objects).
CHUNK_SIZE = 100
ITER_CHUNK_SIZE = CHUNK_SIZE
# The maximum number of items to display in a QuerySet.__repr__
REPR_OUTPUT_SIZE = 20
# Pull into this namespace for backwards compatibility.
EmptyResultSet = sql.EmptyResultSet
class QuerySet(object):
"""
Represents a lazy database lookup for a set of objects.
"""
def __init__(self, model=None, query=None, using=None):
self.model = model
# EmptyQuerySet instantiates QuerySet with model as None
self._db = using
self.query = query or sql.Query(self.model)
self._result_cache = None
self._iter = None
self._sticky_filter = False
self._for_write = False
########################
# PYTHON MAGIC METHODS #
########################
def __deepcopy__(self, memo):
"""
Deep copy of a QuerySet doesn't populate the cache
"""
obj = self.__class__()
for k,v in self.__dict__.items():
if k in ('_iter','_result_cache'):
obj.__dict__[k] = None
else:
obj.__dict__[k] = deepcopy(v, memo)
return obj
def __getstate__(self):
"""
Allows the QuerySet to be pickled.
"""
# Force the cache to be fully populated.
len(self)
obj_dict = self.__dict__.copy()
obj_dict['_iter'] = None
return obj_dict
def __repr__(self):
data = list(self[:REPR_OUTPUT_SIZE + 1])
if len(data) > REPR_OUTPUT_SIZE:
data[-1] = "...(remaining elements truncated)..."
return repr(data)
def __len__(self):
# Since __len__ is called quite frequently (for example, as part of
# list(qs), we make some effort here to be as efficient as possible
# whilst not messing up any existing iterators against the QuerySet.
if self._result_cache is None:
if self._iter:
self._result_cache = list(self._iter)
else:
self._result_cache = list(self.iterator())
elif self._iter:
self._result_cache.extend(list(self._iter))
return len(self._result_cache)
def __iter__(self):
if self._result_cache is None:
self._iter = self.iterator()
self._result_cache = []
if self._iter:
return self._result_iter()
# Python's list iterator is better than our version when we're just
# iterating over the cache.
return iter(self._result_cache)
def _result_iter(self):
pos = 0
while 1:
upper = len(self._result_cache)
while pos < upper:
yield self._result_cache[pos]
pos = pos + 1
if not self._iter:
raise StopIteration
if len(self._result_cache) <= pos:
self._fill_cache()
def __nonzero__(self):
if self._result_cache is not None:
return bool(self._result_cache)
try:
iter(self).next()
except StopIteration:
return False
return True
def __contains__(self, val):
# The 'in' operator works without this method, due to __iter__. This
# implementation exists only to shortcut the creation of Model
# instances, by bailing out early if we find a matching element.
pos = 0
if self._result_cache is not None:
if val in self._result_cache:
return True
elif self._iter is None:
# iterator is exhausted, so we have our answer
return False
# remember not to check these again:
pos = len(self._result_cache)
else:
# We need to start filling the result cache out. The following
# ensures that self._iter is not None and self._result_cache is not
# None
it = iter(self)
# Carry on, one result at a time.
while True:
if len(self._result_cache) <= pos:
self._fill_cache(num=1)
if self._iter is None:
# we ran out of items
return False
if self._result_cache[pos] == val:
return True
pos += 1
def __getitem__(self, k):
"""
Retrieves an item or slice from the set of results.
"""
if not isinstance(k, (slice, int, long)):
raise TypeError
assert ((not isinstance(k, slice) and (k >= 0))
or (isinstance(k, slice) and (k.start is None or k.start >= 0)
and (k.stop is None or k.stop >= 0))), \
"Negative indexing is not supported."
if self._result_cache is not None:
if self._iter is not None:
# The result cache has only been partially populated, so we may
# need to fill it out a bit more.
if isinstance(k, slice):
if k.stop is not None:
# Some people insist on passing in strings here.
bound = int(k.stop)
else:
bound = None
else:
bound = k + 1
if len(self._result_cache) < bound:
self._fill_cache(bound - len(self._result_cache))
return self._result_cache[k]
if isinstance(k, slice):
qs = self._clone()
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 k.step and list(qs)[::k.step] or qs
try:
qs = self._clone()
qs.query.set_limits(k, k + 1)
return list(qs)[0]
except self.model.DoesNotExist, e:
raise IndexError(e.args)
def __and__(self, other):
self._merge_sanity_check(other)
if isinstance(other, EmptyQuerySet):
return other._clone()
combined = self._clone()
combined.query.combine(other.query, sql.AND)
return combined
def __or__(self, other):
self._merge_sanity_check(other)
combined = self._clone()
if isinstance(other, EmptyQuerySet):
return combined
combined.query.combine(other.query, sql.OR)
return combined
####################################
# METHODS THAT DO DATABASE QUERIES #
####################################
def iterator(self):
"""
An iterator over the results from applying this QuerySet to the
database.
"""
fill_cache = self.query.select_related
if isinstance(fill_cache, dict):
requested = fill_cache
else:
requested = None
max_depth = self.query.max_depth
extra_select = self.query.extra_select.keys()
aggregate_select = self.query.aggregate_select.keys()
only_load = self.query.get_loaded_field_names()
if not fill_cache:
fields = self.model._meta.fields
pk_idx = self.model._meta.pk_index()
index_start = len(extra_select)
aggregate_start = index_start + len(self.model._meta.fields)
load_fields = []
# If only/defer clauses have been specified,
# build the list of fields that are to be loaded.
if only_load:
for field, model in self.model._meta.get_fields_with_model():
if model is None:
model = self.model
if field == self.model._meta.pk:
# Record the index of the primary key when it is found
pk_idx = len(load_fields)
try:
if field.name in only_load[model]:
# Add a field that has been explicitly included
load_fields.append(field.name)
except KeyError:
# Model wasn't explicitly listed in the only_load table
# Therefore, we need to load all fields from this model
load_fields.append(field.name)
skip = None
if load_fields and not fill_cache:
# Some fields have been deferred, so we have to initialise
# via keyword arguments.
skip = set()
init_list = []
for field in fields:
if field.name not in load_fields:
skip.add(field.attname)
else:
init_list.append(field.attname)
model_cls = deferred_class_factory(self.model, skip)
compiler = self.query.get_compiler(using=self.db)
for row in compiler.results_iter():
if fill_cache:
obj, _ = get_cached_row(self.model, row,
index_start, using=self.db, max_depth=max_depth,
requested=requested, offset=len(aggregate_select),
only_load=only_load)
else:
if skip:
row_data = row[index_start:aggregate_start]
pk_val = row_data[pk_idx]
obj = model_cls(**dict(zip(init_list, row_data)))
else:
# Omit aggregates in object creation.
obj = self.model(*row[index_start:aggregate_start])
# Store the source database of the object
obj._state.db = self.db
for i, k in enumerate(extra_select):
setattr(obj, k, row[i])
# Add the aggregates to the model
for i, aggregate in enumerate(aggregate_select):
setattr(obj, aggregate, row[i+aggregate_start])
yield obj
def aggregate(self, *args, **kwargs):
"""
Returns 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.
"""
for arg in args:
kwargs[arg.default_alias] = arg
query = self.query.clone()
for (alias, aggregate_expr) in kwargs.items():
query.add_aggregate(aggregate_expr, self.model, alias,
is_summary=True)
return query.get_aggregation(using=self.db)
def count(self):
"""
Performs a SELECT COUNT() and returns the number of records as an
integer.
If the QuerySet is already fully cached this simply returns the length
of the cached results set to avoid multiple SELECT COUNT(*) calls.
"""
if self._result_cache is not None and not self._iter:
return len(self._result_cache)
return self.query.get_count(using=self.db)
def get(self, *args, **kwargs):
"""
Performs the query and returns a single object matching the given
keyword arguments.
"""
clone = self.filter(*args, **kwargs)
if self.query.can_filter():
clone = clone.order_by()
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! Lookup parameters were %s"
% (self.model._meta.object_name, num, kwargs))
def create(self, **kwargs):
"""
Creates a new object with the given kwargs, saving it to the database
and returning the created object.
"""
obj = self.model(**kwargs)
self._for_write = True
obj.save(force_insert=True, using=self.db)
return obj
def get_or_create(self, **kwargs):
"""
Looks up an object with the given kwargs, creating one if necessary.
Returns a tuple of (object, created), where created is a boolean
specifying whether an object was created.
"""
assert kwargs, \
'get_or_create() must be passed at least one keyword argument'
defaults = kwargs.pop('defaults', {})
try:
self._for_write = True
return self.get(**kwargs), False
except self.model.DoesNotExist:
try:
params = dict([(k, v) for k, v in kwargs.items() if '__' not in k])
params.update(defaults)
obj = self.model(**params)
sid = transaction.savepoint(using=self.db)
obj.save(force_insert=True, using=self.db)
transaction.savepoint_commit(sid, using=self.db)
return obj, True
except IntegrityError, e:
transaction.savepoint_rollback(sid, using=self.db)
try:
return self.get(**kwargs), False
except self.model.DoesNotExist:
raise e
def latest(self, field_name=None):
"""
Returns the latest object, according to the model's 'get_latest_by'
option or optional given field_name.
"""
latest_by = field_name or self.model._meta.get_latest_by
assert bool(latest_by), "latest() requires either a field_name parameter or 'get_latest_by' in the model"
assert self.query.can_filter(), \
"Cannot change a query once a slice has been taken."
obj = self._clone()
obj.query.set_limits(high=1)
obj.query.add_ordering('-%s' % latest_by)
return obj.get()
def in_bulk(self, id_list):
"""
Returns a dictionary mapping each of the given IDs to the object with
that ID.
"""
assert self.query.can_filter(), \
"Cannot use 'limit' or 'offset' with in_bulk"
assert isinstance(id_list, (tuple, list, set, frozenset)), \
"in_bulk() must be provided with a list of IDs."
if not id_list:
return {}
qs = self._clone()
qs.query.add_filter(('pk__in', id_list))
return dict([(obj._get_pk_val(), obj) for obj in qs.iterator()])
def delete(self):
"""
Deletes the records in the current QuerySet.
"""
assert self.query.can_filter(), \
"Cannot use 'limit' or 'offset' with delete."
del_query = self._clone()
# 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_related = False
del_query.query.clear_ordering()
# Delete objects in chunks to prevent the list of related objects from
# becoming too long.
seen_objs = None
del_itr = iter(del_query)
while 1:
# Collect a chunk of objects to be deleted, and then all the
# objects that are related to the objects that are to be deleted.
# The chunking *isn't* done by slicing the del_query because we
# need to maintain the query cache on del_query (see #12328)
seen_objs = CollectedObjects(seen_objs)
for i, obj in izip(xrange(CHUNK_SIZE), del_itr):
obj._collect_sub_objects(seen_objs)
if not seen_objs:
break
delete_objects(seen_objs, del_query.db)
# Clear the result cache, in case this QuerySet gets reused.
self._result_cache = None
delete.alters_data = True
def update(self, **kwargs):
"""
Updates all elements in the current QuerySet, setting all the given
fields to the appropriate values.
"""
assert self.query.can_filter(), \
"Cannot update a query once a slice has been taken."
self._for_write = True
query = self.query.clone(sql.UpdateQuery)
query.add_update_values(kwargs)
if not transaction.is_managed(using=self.db):
transaction.enter_transaction_management(using=self.db)
forced_managed = True
else:
forced_managed = False
try:
rows = query.get_compiler(self.db).execute_sql(None)
if forced_managed:
transaction.commit(using=self.db)
else:
transaction.commit_unless_managed(using=self.db)
finally:
if forced_managed:
transaction.leave_transaction_management(using=self.db)
self._result_cache = None
return rows
update.alters_data = True
def _update(self, values):
"""
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).
"""
assert self.query.can_filter(), \
"Cannot update a query once a slice has been taken."
query = self.query.clone(sql.UpdateQuery)
query.add_update_fields(values)
self._result_cache = None
return query.get_compiler(self.db).execute_sql(None)
_update.alters_data = True
def exists(self):
if self._result_cache is None:
return self.query.has_results(using=self.db)
return bool(self._result_cache)
##################################################
# PUBLIC METHODS THAT RETURN A QUERYSET SUBCLASS #
##################################################
def values(self, *fields):
return self._clone(klass=ValuesQuerySet, setup=True, _fields=fields)
def values_list(self, *fields, **kwargs):
flat = kwargs.pop('flat', False)
if kwargs:
raise TypeError('Unexpected keyword arguments to values_list: %s'
% (kwargs.keys(),))
if flat and len(fields) > 1:
raise TypeError("'flat' is not valid when values_list is called with more than one field.")
return self._clone(klass=ValuesListQuerySet, setup=True, flat=flat,
_fields=fields)
def dates(self, field_name, kind, order='ASC'):
"""
Returns a list of datetime objects representing all available dates for
the given field_name, scoped to 'kind'.
"""
assert kind in ("month", "year", "day"), \
"'kind' must be one of 'year', 'month' or 'day'."
assert order in ('ASC', 'DESC'), \
"'order' must be either 'ASC' or 'DESC'."
return self._clone(klass=DateQuerySet, setup=True,
_field_name=field_name, _kind=kind, _order=order)
def none(self):
"""
Returns an empty QuerySet.
"""
return self._clone(klass=EmptyQuerySet)
##################################################################
# PUBLIC METHODS THAT ALTER ATTRIBUTES AND RETURN A NEW QUERYSET #
##################################################################
def all(self):
"""
Returns 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._clone()
def filter(self, *args, **kwargs):
"""
Returns a new QuerySet instance with the args ANDed to the existing
set.
"""
return self._filter_or_exclude(False, *args, **kwargs)
def exclude(self, *args, **kwargs):
"""
Returns a new QuerySet instance with NOT (args) ANDed to the existing
set.
"""
return self._filter_or_exclude(True, *args, **kwargs)
def _filter_or_exclude(self, negate, *args, **kwargs):
if args or kwargs:
assert self.query.can_filter(), \
"Cannot filter a query once a slice has been taken."
clone = self._clone()
if negate:
clone.query.add_q(~Q(*args, **kwargs))
else:
clone.query.add_q(Q(*args, **kwargs))
return clone
def complex_filter(self, filter_obj):
"""
Returns a new QuerySet instance with filter_obj added to the filters.
filter_obj can be a Q object (or anything with an add_to_query()
method) 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) or hasattr(filter_obj, 'add_to_query'):
clone = self._clone()
clone.query.add_q(filter_obj)
return clone
else:
return self._filter_or_exclude(None, **filter_obj)
def select_related(self, *fields, **kwargs):
"""
Returns 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.
"""
depth = kwargs.pop('depth', 0)
if kwargs:
raise TypeError('Unexpected keyword arguments to select_related: %s'
% (kwargs.keys(),))
obj = self._clone()
if fields:
if depth:
raise TypeError('Cannot pass both "depth" and fields to select_related()')
obj.query.add_select_related(fields)
else:
obj.query.select_related = True
if depth:
obj.query.max_depth = depth
return obj
def dup_select_related(self, other):
"""
Copies the related selection status from the QuerySet 'other' to the
current QuerySet.
"""
self.query.select_related = other.query.select_related
def annotate(self, *args, **kwargs):
"""
Return a query set in which the returned objects have been annotated
with data aggregated from related fields.
"""
for arg in args:
kwargs[arg.default_alias] = arg
obj = self._clone()
obj._setup_aggregate_query(kwargs.keys())
# Add the aggregates to the query
for (alias, aggregate_expr) in kwargs.items():
obj.query.add_aggregate(aggregate_expr, self.model, alias,
is_summary=False)
return obj
def order_by(self, *field_names):
"""
Returns a new QuerySet instance with the ordering changed.
"""
assert self.query.can_filter(), \
"Cannot reorder a query once a slice has been taken."
obj = self._clone()
obj.query.clear_ordering()
obj.query.add_ordering(*field_names)
return obj
def distinct(self, true_or_false=True):
"""
Returns a new QuerySet instance that will select only distinct results.
"""
obj = self._clone()
obj.query.distinct = true_or_false
return obj
def extra(self, select=None, where=None, params=None, tables=None,
order_by=None, select_params=None):
"""
Adds extra SQL fragments to the query.
"""
assert self.query.can_filter(), \
"Cannot change a query once a slice has been taken"
clone = self._clone()
clone.query.add_extra(select, select_params, where, params, tables, order_by)
return clone
def reverse(self):
"""
Reverses the ordering of the QuerySet.
"""
clone = self._clone()
clone.query.standard_ordering = not clone.query.standard_ordering
return clone
def defer(self, *fields):
"""
Defers the loading of data for certain fields until they are accessed.
The set of fields to defer is added 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 all deferrals are removed (None acts as a
reset option).
"""
clone = self._clone()
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.
"""
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().")
clone = self._clone()
clone.query.add_immediate_loading(fields)
return clone
def using(self, alias):
"""
Selects which database this QuerySet should excecute it's query against.
"""
clone = self._clone()
clone._db = alias
return clone
###################################
# PUBLIC INTROSPECTION ATTRIBUTES #
###################################
def ordered(self):
"""
Returns True if the QuerySet is ordered -- i.e. has an order_by()
clause or a default ordering on the model.
"""
if self.query.extra_order_by or self.query.order_by:
return True
elif self.query.default_ordering and self.query.model._meta.ordering:
return True
else:
return False
ordered = property(ordered)
@property
def db(self):
"Return the database that will be used if this query is executed now"
if self._for_write:
return self._db or router.db_for_write(self.model)
return self._db or router.db_for_read(self.model)
###################
# PRIVATE METHODS #
###################
def _clone(self, klass=None, setup=False, **kwargs):
if klass is None:
klass = self.__class__
query = self.query.clone()
if self._sticky_filter:
query.filter_is_sticky = True
c = klass(model=self.model, query=query, using=self._db)
c._for_write = self._for_write
c.__dict__.update(kwargs)
if setup and hasattr(c, '_setup_query'):
c._setup_query()
return c
def _fill_cache(self, num=None):
"""
Fills the result cache with 'num' more entries (or until the results
iterator is exhausted).
"""
if self._iter:
try:
for i in range(num or ITER_CHUNK_SIZE):
self._result_cache.append(self._iter.next())
except StopIteration:
self._iter = None
def _next_is_sticky(self):
"""
Indicates 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):
"""
Checks that we are merging two comparable QuerySet classes. By default
this does nothing, but see the ValuesQuerySet for an example of where
it's useful.
"""
pass
def _setup_aggregate_query(self, aggregates):
"""
Prepare the query for computing a result that contains aggregate annotations.
"""
opts = self.model._meta
if self.query.group_by is None:
field_names = [f.attname for f in opts.fields]
self.query.add_fields(field_names, False)
self.query.set_group_by()
def _prepare(self):
return self
def _as_sql(self, connection):
"""
Returns the internal query's SQL and parameters (as a tuple).
"""
obj = self.values("pk")
if obj._db is None or connection == connections[obj._db]:
return obj.query.get_compiler(connection=connection).as_nested_sql()
raise ValueError("Can't do subqueries with queries on different DBs.")
# When used as part of a nested query, a queryset will never be an "always
# empty" result.
value_annotation = True
class ValuesQuerySet(QuerySet):
def __init__(self, *args, **kwargs):
super(ValuesQuerySet, self).__init__(*args, **kwargs)
# select_related isn't supported in values(). (FIXME -#3358)
self.query.select_related = False
# QuerySet.clone() will also set up the _fields attribute with the
# names of the model fields to select.
def iterator(self):
# Purge any extra columns that haven't been explicitly asked for
extra_names = self.query.extra_select.keys()
field_names = self.field_names
aggregate_names = self.query.aggregate_select.keys()
names = extra_names + field_names + aggregate_names
for row in self.query.get_compiler(self.db).results_iter():
yield dict(zip(names, row))
def _setup_query(self):
"""
Constructs the field_names list that the values query will be
retrieving.
Called by the _clone() method after initializing the rest of the
instance.
"""
self.query.clear_deferred_loading()
self.query.clear_select_fields()
if self._fields:
self.extra_names = []
self.aggregate_names = []
if not self.query.extra and not self.query.aggregates:
# Short cut - if there are no extra or aggregates, then
# the values() clause must be just field names.
self.field_names = list(self._fields)
else:
self.query.default_cols = False
self.field_names = []
for f in self._fields:
# we inspect the full extra_select list since we might
# be adding back an extra select item that we hadn't
# had selected previously.
if self.query.extra.has_key(f):
self.extra_names.append(f)
elif self.query.aggregate_select.has_key(f):
self.aggregate_names.append(f)
else:
self.field_names.append(f)
else:
# Default to all fields.
self.extra_names = None
self.field_names = [f.attname for f in self.model._meta.fields]
self.aggregate_names = None
self.query.select = []
if self.extra_names is not None:
self.query.set_extra_mask(self.extra_names)
self.query.add_fields(self.field_names, False)
if self.aggregate_names is not None:
self.query.set_aggregate_mask(self.aggregate_names)
def _clone(self, klass=None, setup=False, **kwargs):
"""
Cloning a ValuesQuerySet preserves the current fields.
"""
c = super(ValuesQuerySet, self)._clone(klass, **kwargs)
if not hasattr(c, '_fields'):
# Only clone self._fields if _fields wasn't passed into the cloning
# call directly.
c._fields = self._fields[:]
c.field_names = self.field_names
c.extra_names = self.extra_names
c.aggregate_names = self.aggregate_names
if setup and hasattr(c, '_setup_query'):
c._setup_query()
return c
def _merge_sanity_check(self, other):
super(ValuesQuerySet, self)._merge_sanity_check(other)
if (set(self.extra_names) != set(other.extra_names) or
set(self.field_names) != set(other.field_names) or
self.aggregate_names != other.aggregate_names):
raise TypeError("Merging '%s' classes must involve the same values in each case."
% self.__class__.__name__)
def _setup_aggregate_query(self, aggregates):
"""
Prepare the query for computing a result that contains aggregate annotations.
"""
self.query.set_group_by()
if self.aggregate_names is not None:
self.aggregate_names.extend(aggregates)
self.query.set_aggregate_mask(self.aggregate_names)
super(ValuesQuerySet, self)._setup_aggregate_query(aggregates)
def _as_sql(self, connection):
"""
For ValueQuerySet (and subclasses like ValuesListQuerySet), they can
only be used as nested queries if they're already set up to select only
a single field (in which case, that is the field column that is
returned). This differs from QuerySet.as_sql(), where the column to
select is set up by Django.
"""
if ((self._fields and len(self._fields) > 1) or
(not self._fields and len(self.model._meta.fields) > 1)):
raise TypeError('Cannot use a multi-field %s as a filter value.'
% self.__class__.__name__)
obj = self._clone()
if obj._db is None or connection == connections[obj._db]:
return obj.query.get_compiler(connection=connection).as_nested_sql()
raise ValueError("Can't do subqueries with queries on different DBs.")
def _prepare(self):
"""
Validates that we aren't trying to do a query like
value__in=qs.values('value1', 'value2'), which isn't valid.
"""
if ((self._fields and len(self._fields) > 1) or
(not self._fields and len(self.model._meta.fields) > 1)):
raise TypeError('Cannot use a multi-field %s as a filter value.'
% self.__class__.__name__)
return self
class ValuesListQuerySet(ValuesQuerySet):
def iterator(self):
if self.flat and len(self._fields) == 1:
for row in self.query.get_compiler(self.db).results_iter():
yield row[0]
elif not self.query.extra_select and not self.query.aggregate_select:
for row in self.query.get_compiler(self.db).results_iter():
yield tuple(row)
else:
# When extra(select=...) or an annotation is involved, the extra
# cols are always at the start of the row, and we need to reorder
# the fields to match the order in self._fields.
extra_names = self.query.extra_select.keys()
field_names = self.field_names
aggregate_names = self.query.aggregate_select.keys()
names = extra_names + field_names + aggregate_names
# If a field list has been specified, use it. Otherwise, use the
# full list of fields, including extras and aggregates.
if self._fields:
fields = list(self._fields) + filter(lambda f: f not in self._fields,
aggregate_names)
else:
fields = names
for row in self.query.get_compiler(self.db).results_iter():
data = dict(zip(names, row))
yield tuple([data[f] for f in fields])
def _clone(self, *args, **kwargs):
clone = super(ValuesListQuerySet, self)._clone(*args, **kwargs)
clone.flat = self.flat
return clone
class DateQuerySet(QuerySet):
def iterator(self):
return self.query.get_compiler(self.db).results_iter()
def _setup_query(self):
"""
Sets up any special features of the query attribute.
Called by the _clone() method after initializing the rest of the
instance.
"""
self.query.clear_deferred_loading()
self.query = self.query.clone(klass=sql.DateQuery, setup=True)
self.query.select = []
field = self.model._meta.get_field(self._field_name, many_to_many=False)
assert isinstance(field, DateField), "%r isn't a DateField." \
% field.name
self.query.add_date_select(field, self._kind, self._order)
if field.null:
self.query.add_filter(('%s__isnull' % field.name, False))
def _clone(self, klass=None, setup=False, **kwargs):
c = super(DateQuerySet, self)._clone(klass, False, **kwargs)
c._field_name = self._field_name
c._kind = self._kind
if setup and hasattr(c, '_setup_query'):
c._setup_query()
return c
class EmptyQuerySet(QuerySet):
def __init__(self, model=None, query=None, using=None):
super(EmptyQuerySet, self).__init__(model, query, using)
self._result_cache = []
def __and__(self, other):
return self._clone()
def __or__(self, other):
return other._clone()
def count(self):
return 0
def delete(self):
pass
def _clone(self, klass=None, setup=False, **kwargs):
c = super(EmptyQuerySet, self)._clone(klass, **kwargs)
c._result_cache = []
return c
def iterator(self):
# This slightly odd construction is because we need an empty generator
# (it raises StopIteration immediately).
yield iter([]).next()
def all(self):
"""
Always returns EmptyQuerySet.
"""
return self
def filter(self, *args, **kwargs):
"""
Always returns EmptyQuerySet.
"""
return self
def exclude(self, *args, **kwargs):
"""
Always returns EmptyQuerySet.
"""
return self
def complex_filter(self, filter_obj):
"""
Always returns EmptyQuerySet.
"""
return self
def select_related(self, *fields, **kwargs):
"""
Always returns EmptyQuerySet.
"""
return self
def annotate(self, *args, **kwargs):
"""
Always returns EmptyQuerySet.
"""
return self
def order_by(self, *field_names):
"""
Always returns EmptyQuerySet.
"""
return self
def distinct(self, true_or_false=True):
"""
Always returns EmptyQuerySet.
"""
return self
def extra(self, select=None, where=None, params=None, tables=None,
order_by=None, select_params=None):
"""
Always returns EmptyQuerySet.
"""
assert self.query.can_filter(), \
"Cannot change a query once a slice has been taken"
return self
def reverse(self):
"""
Always returns EmptyQuerySet.
"""
return self
def defer(self, *fields):
"""
Always returns EmptyQuerySet.
"""
return self
def only(self, *fields):
"""
Always returns EmptyQuerySet.
"""
return self
def update(self, **kwargs):
"""
Don't update anything.
"""
return 0
# EmptyQuerySet is always an empty result in where-clauses (and similar
# situations).
value_annotation = False
def get_cached_row(klass, row, index_start, using, max_depth=0, cur_depth=0,
requested=None, offset=0, only_load=None, local_only=False):
"""
Helper function that recursively returns an object with the specified
related attributes already populated.
This method may be called recursively to populate deep select_related()
clauses.
Arguments:
* klass - the class to retrieve (and instantiate)
* row - the row of data returned by the database cursor
* index_start - the index of the row at which data for this
object is known to start
* using - the database alias on which the query is being executed.
* max_depth - the maximum depth to which a select_related()
relationship should be explored.
* cur_depth - the current depth in the select_related() tree.
Used in recursive calls to determin if we should dig deeper.
* requested - A dictionary describing the select_related() tree
that is to be retrieved. keys are field names; values are
dictionaries describing the keys on that related object that
are themselves to be select_related().
* offset - the number of additional fields that are known to
exist in `row` for `klass`. This usually means the number of
annotated results on `klass`.
* only_load - if the query has had only() or defer() applied,
this is the list of field names that will be returned. If None,
the full field list for `klass` can be assumed.
* local_only - Only populate local fields. This is used when building
following reverse select-related relations
"""
if max_depth and requested is None and cur_depth > max_depth:
# We've recursed deeply enough; stop now.
return None
restricted = requested is not None
if only_load:
load_fields = only_load.get(klass)
# When we create the object, we will also be creating populating
# all the parent classes, so traverse the parent classes looking
# for fields that must be included on load.
for parent in klass._meta.get_parent_list():
fields = only_load.get(parent)
if fields:
load_fields.update(fields)
else:
load_fields = None
if load_fields:
# Handle deferred fields.
skip = set()
init_list = []
# Build the list of fields that *haven't* been requested
for field, model in klass._meta.get_fields_with_model():
if field.name not in load_fields:
skip.add(field.name)
elif local_only and model is not None:
continue
else:
init_list.append(field.attname)
# Retrieve all the requested fields
field_count = len(init_list)
fields = row[index_start : index_start + field_count]
# If all the select_related columns are None, then the related
# object must be non-existent - set the relation to None.
# Otherwise, construct the related object.
if fields == (None,) * field_count:
obj = None
elif skip:
klass = deferred_class_factory(klass, skip)
obj = klass(**dict(zip(init_list, fields)))
else:
obj = klass(*fields)
else:
# Load all fields on klass
if local_only:
field_names = [f.attname for f in klass._meta.local_fields]
else:
field_names = [f.attname for f in klass._meta.fields]
field_count = len(field_names)
fields = row[index_start : index_start + field_count]
# If all the select_related columns are None, then the related
# object must be non-existent - set the relation to None.
# Otherwise, construct the related object.
if fields == (None,) * field_count:
obj = None
else:
obj = klass(**dict(zip(field_names, fields)))
# If an object was retrieved, set the database state.
if obj:
obj._state.db = using
index_end = index_start + field_count + offset
# Iterate over each related object, populating any
# select_related() fields
for f in klass._meta.fields:
if not select_related_descend(f, restricted, requested):
continue
if restricted:
next = requested[f.name]
else:
next = None
# Recursively retrieve the data for the related object
cached_row = get_cached_row(f.rel.to, row, index_end, using,
max_depth, cur_depth+1, next, only_load=only_load)
# If the recursive descent found an object, populate the
# descriptor caches relevant to the object
if cached_row:
rel_obj, index_end = cached_row
if obj is not None:
# If the base object exists, populate the
# descriptor cache
setattr(obj, f.get_cache_name(), rel_obj)
if f.unique and rel_obj is not None:
# If the field is unique, populate the
# reverse descriptor cache on the related object
setattr(rel_obj, f.related.get_cache_name(), obj)
# Now do the same, but for reverse related objects.
# Only handle the restricted case - i.e., don't do a depth
# descent into reverse relations unless explicitly requested
if restricted:
related_fields = [
(o.field, o.model)
for o in klass._meta.get_all_related_objects()
if o.field.unique
]
for f, model in related_fields:
if not select_related_descend(f, restricted, requested, reverse=True):
continue
next = requested[f.related_query_name()]
# Recursively retrieve the data for the related object
cached_row = get_cached_row(model, row, index_end, using,
max_depth, cur_depth+1, next, only_load=only_load, local_only=True)
# If the recursive descent found an object, populate the
# descriptor caches relevant to the object
if cached_row:
rel_obj, index_end = cached_row
if obj is not None:
# If the field is unique, populate the
# reverse descriptor cache
setattr(obj, f.related.get_cache_name(), rel_obj)
if rel_obj is not None:
# If the related object exists, populate
# the descriptor cache.
setattr(rel_obj, f.get_cache_name(), obj)
# Now populate all the non-local field values
# on the related object
for rel_field,rel_model in rel_obj._meta.get_fields_with_model():
if rel_model is not None:
setattr(rel_obj, rel_field.attname, getattr(obj, rel_field.attname))
# populate the field cache for any related object
# that has already been retrieved
if rel_field.rel:
try:
cached_obj = getattr(obj, rel_field.get_cache_name())
setattr(rel_obj, rel_field.get_cache_name(), cached_obj)
except AttributeError:
# Related object hasn't been cached yet
pass
return obj, index_end
def delete_objects(seen_objs, using):
"""
Iterate through a list of seen classes, and remove any instances that are
referred to.
"""
connection = connections[using]
if not transaction.is_managed(using=using):
transaction.enter_transaction_management(using=using)
forced_managed = True
else:
forced_managed = False
try:
ordered_classes = seen_objs.keys()
except CyclicDependency:
# If there is a cyclic dependency, we cannot in general delete the
# objects. However, if an appropriate transaction is set up, or if the
# database is lax enough, it will succeed. So for now, we go ahead and
# try anyway.
ordered_classes = seen_objs.unordered_keys()
obj_pairs = {}
try:
for cls in ordered_classes:
items = seen_objs[cls].items()
items.sort()
obj_pairs[cls] = items
# Pre-notify all instances to be deleted.
for pk_val, instance in items:
if not cls._meta.auto_created:
signals.pre_delete.send(sender=cls, instance=instance)
pk_list = [pk for pk,instance in items]
update_query = sql.UpdateQuery(cls)
for field, model in cls._meta.get_fields_with_model():
if (field.rel and field.null and field.rel.to in seen_objs and
filter(lambda f: f.column == field.rel.get_related_field().column,
field.rel.to._meta.fields)):
if model:
sql.UpdateQuery(model).clear_related(field, pk_list, using=using)
else:
update_query.clear_related(field, pk_list, using=using)
# Now delete the actual data.
for cls in ordered_classes:
items = obj_pairs[cls]
items.reverse()
pk_list = [pk for pk,instance in items]
del_query = sql.DeleteQuery(cls)
del_query.delete_batch(pk_list, using=using)
# Last cleanup; set NULLs where there once was a reference to the
# object, NULL the primary key of the found objects, and perform
# post-notification.
for pk_val, instance in items:
for field in cls._meta.fields:
if field.rel and field.null and field.rel.to in seen_objs:
setattr(instance, field.attname, None)
if not cls._meta.auto_created:
signals.post_delete.send(sender=cls, instance=instance)
setattr(instance, cls._meta.pk.attname, None)
if forced_managed:
transaction.commit(using=using)
else:
transaction.commit_unless_managed(using=using)
finally:
if forced_managed:
transaction.leave_transaction_management(using=using)
class RawQuerySet(object):
"""
Provides an iterator which converts the results of raw SQL queries into
annotated model instances.
"""
def __init__(self, raw_query, model=None, query=None, params=None,
translations=None, using=None):
self.raw_query = raw_query
self.model = model
self._db = using
self.query = query or sql.RawQuery(sql=raw_query, using=self.db, params=params)
self.params = params or ()
self.translations = translations or {}
def __iter__(self):
for row in self.query:
yield self.transform_results(row)
def __repr__(self):
return "<RawQuerySet: %r>" % (self.raw_query % self.params)
def __getitem__(self, k):
return list(self)[k]
@property
def db(self):
"Return the database that will be used if this query is executed now"
return self._db or router.db_for_read(self.model)
def using(self, alias):
"""
Selects which database this Raw QuerySet should excecute it's query against.
"""
return RawQuerySet(self.raw_query, model=self.model,
query=self.query.clone(using=alias),
params=self.params, translations=self.translations,
using=alias)
@property
def columns(self):
"""
A list of model field names in the order they'll appear in the
query results.
"""
if not hasattr(self, '_columns'):
self._columns = self.query.get_columns()
# Adjust any column names which don't match field names
for (query_name, model_name) in self.translations.items():
try:
index = self._columns.index(query_name)
self._columns[index] = model_name
except ValueError:
# Ignore translations for non-existant column names
pass
return self._columns
@property
def model_fields(self):
"""
A dict mapping column names to model field names.
"""
if not hasattr(self, '_model_fields'):
converter = connections[self.db].introspection.table_name_converter
self._model_fields = {}
for field in self.model._meta.fields:
name, column = field.get_attname_column()
self._model_fields[converter(column)] = field
return self._model_fields
def transform_results(self, values):
model_init_kwargs = {}
annotations = ()
# Perform database backend type resolution
connection = connections[self.db]
compiler = connection.ops.compiler('SQLCompiler')(self.query, connection, self.db)
if hasattr(compiler, 'resolve_columns'):
fields = [self.model_fields.get(c,None) for c in self.columns]
values = compiler.resolve_columns(values, fields)
# Associate fields to values
for pos, value in enumerate(values):
column = self.columns[pos]
# Separate properties from annotations
if column in self.model_fields.keys():
model_init_kwargs[self.model_fields[column].attname] = value
else:
annotations += (column, value),
# Construct model instance and apply annotations
skip = set()
for field in self.model._meta.fields:
if field.attname not in model_init_kwargs.keys():
skip.add(field.attname)
if skip:
if self.model._meta.pk.attname in skip:
raise InvalidQuery('Raw query must include the primary key')
model_cls = deferred_class_factory(self.model, skip)
else:
model_cls = self.model
instance = model_cls(**model_init_kwargs)
for field, value in annotations:
setattr(instance, field, value)
instance._state.db = self.query.using
return instance
def insert_query(model, values, return_id=False, raw_values=False, using=None):
"""
Inserts a new record for the given model. This provides an interface to
the InsertQuery class and is how Model.save() is implemented. It is not
part of the public API.
"""
query = sql.InsertQuery(model)
query.insert_values(values, raw_values)
return query.get_compiler(using=using).execute_sql(return_id)
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