blinkster: comparison web/lib/django/db/models/query.py

equal deleted inserted replaced

-:8d941af65caf
+:77b6da96e6f1
+"""
+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)