py_tasks_melange: comparison app/django/db/models/query.py

equal deleted inserted replaced

-:6641e941ef1e
+:ff1a9aa48cfd
-import warnings
+try:
+set
-from django.conf import settings
+except NameError:
+from sets import Set as set     # Python 2.3 fallback
 from django.db import connection, transaction, IntegrityError
-from django.db.models.fields import DateField, FieldDoesNotExist
+from django.db.models.fields import DateField
-from django.db.models.query_utils import Q
+from django.db.models.query_utils import Q, select_related_descend
 from django.db.models import signals, sql
-from django.dispatch import dispatcher
 from django.utils.datastructures import SortedDict
 # 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
-# Pull into this namespace for backwards compatibility
+# 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 CyclicDependency(Exception):
+"""
+An error when dealing with a collection of objects that have a cyclic
+dependency, i.e. when deleting multiple objects.
+"""
+pass
+class CollectedObjects(object):
+"""
+A container that stores keys and lists of values along with remembering the
+parent objects for all the keys.
+This is used for the database object deletion routines so that we can
+calculate the 'leaf' objects which should be deleted first.
+"""
+def __init__(self):
+self.data = {}
+self.children = {}
+def add(self, model, pk, obj, parent_model, nullable=False):
+"""
+Adds an item to the container.
+Arguments:
+* model - the class of the object being added.
+* pk - the primary key.
+* obj - the object itself.
+* parent_model - the model of the parent object that this object was
+reached through.
+* nullable - should be True if this relation is nullable.
+Returns True if the item already existed in the structure and
+False otherwise.
+"""
+d = self.data.setdefault(model, SortedDict())
+retval = pk in d
+d[pk] = obj
+# Nullable relationships can be ignored -- they are nulled out before
+# deleting, and therefore do not affect the order in which objects
+# have to be deleted.
+if parent_model is not None and not nullable:
+self.children.setdefault(parent_model, []).append(model)
+return retval
+def __contains__(self, key):
+return self.data.__contains__(key)
+def __getitem__(self, key):
+return self.data[key]
+def __nonzero__(self):
+return bool(self.data)
+def iteritems(self):
+for k in self.ordered_keys():
+yield k, self[k]
+def items(self):
+return list(self.iteritems())
+def keys(self):
+return self.ordered_keys()
+def ordered_keys(self):
+"""
+Returns the models in the order that they should be dealt with (i.e.
+models with no dependencies first).
+"""
+dealt_with = SortedDict()
+# Start with items that have no children
+models = self.data.keys()
+while len(dealt_with) < len(models):
+found = False
+for model in models:
+if model in dealt_with:
+continue
+children = self.children.setdefault(model, [])
+if len([c for c in children if c not in dealt_with]) == 0:
+dealt_with[model] = None
+found = True
+if not found:
+raise CyclicDependency(
+"There is a cyclic dependency of items to be processed.")
+return dealt_with.keys()
+def unordered_keys(self):
+"""
+Fallback for the case where is a cyclic dependency but we don't  care.
+"""
+return self.data.keys()
 class QuerySet(object):
-"Represents a lazy database lookup for a set of objects"
+"""
+Represents a lazy database lookup for a set of objects.
+"""
 def __init__(self, model=None, query=None):
 self.model = model
 self.query = query or sql.Query(self.model, connection)
 self._result_cache = None
 self._iter = None
+self._sticky_filter = False
 ########################
 # PYTHON MAGIC METHODS #
 ########################
 def __getstate__(self):
 """
-Allows the Queryset to be pickled.
+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):
-return repr(list(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.
+# 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())
 except StopIteration:
 return False
 return True
 def __getitem__(self, k):
-"Retrieve an item or slice from the set of results."
+"""
+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))), \
 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 count(self):
 """
 Performs a SELECT COUNT() and returns the number of records as an
 integer.
-If the queryset is already cached (i.e. self._result_cache is set) this
+If the QuerySet is already fully cached this simply returns the length
-simply returns the length of the cached results set to avoid multiple
+of the cached results set to avoid multiple SELECT COUNT(*) calls.
-SELECT COUNT(*) calls.
+"""
-"""
+if self._result_cache is not None and not self._iter:
-if self._result_cache is not None:
 return len(self._result_cache)
 return self.query.get_count()
 def get(self, *args, **kwargs):
 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):
 """
-Create a new object with the given kwargs, saving it to the database
+Creates a new object with the given kwargs, saving it to the database
 and returning the created object.
 """
 obj = self.model(**kwargs)
-obj.save()
+obj.save(force_insert=True)
 return obj
 def get_or_create(self, **kwargs):
 """
 Looks up an object with the given kwargs, creating one if necessary.
 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)
-obj.save()
+sid = transaction.savepoint()
+obj.save(force_insert=True)
+transaction.savepoint_commit(sid)
 return obj, True
 except IntegrityError, e:
-return self.get(**kwargs), False
+transaction.savepoint_rollback(sid)
+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.
 # Delete objects in chunks to prevent the list of related objects from
 # becoming too long.
 while 1:
 # Collect all the objects to be deleted in this chunk, and all the
 # objects that are related to the objects that are to be deleted.
-seen_objs = SortedDict()
+seen_objs = CollectedObjects()
 for object in del_query[:CHUNK_SIZE]:
 object._collect_sub_objects(seen_objs)
 if not seen_objs:
 break
 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."
 query = self.query.clone(sql.UpdateQuery)
 query.add_update_values(kwargs)
-query.execute_sql(None)
+rows = query.execute_sql(None)
 transaction.commit_unless_managed()
 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)
-query.execute_sql(None)
 self._result_cache = None
+return query.execute_sql(None)
 _update.alters_data = True
 ##################################################
 # PUBLIC METHODS THAT RETURN A QUERYSET SUBCLASS #
 ##################################################
 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
+Returns a list of datetime objects representing all available dates for
-for the given field_name, scoped to 'kind'.
+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'."
-# Let the FieldDoesNotExist exception propagate.
+return self._clone(klass=DateQuerySet, setup=True,
-field = self.model._meta.get_field(field_name, many_to_many=False)
+_field_name=field_name, _kind=kind, _order=order)
-assert isinstance(field, DateField), "%r isn't a DateField." \
-% field_name
-return self._clone(klass=DateQuerySet, setup=True, _field=field,
-_kind=kind, _order=order)
 def none(self):
 """
-Returns an empty queryset.
+Returns an empty QuerySet.
 """
 return self._clone(klass=EmptyQuerySet)
 ##################################################################
 # PUBLIC METHODS THAT ALTER ATTRIBUTES AND RETURN A NEW QUERYSET #
 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'):
-return self._filter_or_exclude(None, filter_obj)
+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
+Returns a new QuerySet instance that will select related objects.
-fields are specified, they must be ForeignKey fields and only those
+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'
 obj.query.max_depth = depth
 return obj
 def dup_select_related(self, other):
 """
-Copies the related selection status from the queryset 'other' to the
+Copies the related selection status from the QuerySet 'other' to the
-current queryset.
+current QuerySet.
 """
 self.query.select_related = other.query.select_related
 def order_by(self, *field_names):
-"""Returns a new QuerySet instance with the ordering changed."""
+"""
+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)
 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):
 """
-Add extra SQL fragments to the query.
+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.
+Reverses the ordering of the QuerySet.
 """
 clone = self._clone()
 clone.query.standard_ordering = not clone.query.standard_ordering
 return clone
 ###################
 def _clone(self, klass=None, setup=False, **kwargs):
 if klass is None:
 klass = self.__class__
-c = klass(model=self.model, query=self.query.clone())
+query = self.query.clone()
+if self._sticky_filter:
+query.filter_is_sticky = True
+c = klass(model=self.model, query=query)
 c.__dict__.update(kwargs)
 if setup and hasattr(c, '_setup_query'):
 c._setup_query()
 return c
 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.
+Checks that we are merging two comparable QuerySet classes. By default
-"""
+this does nothing, but see the ValuesQuerySet for an example of where
-if self.__class__ is not other.__class__:
+it's useful.
-raise TypeError("Cannot merge querysets of different types ('%s' and '%s'."
+"""
-% (self.__class__.__name__, other.__class__.__name__))
+pass
 class ValuesQuerySet(QuerySet):
 def __init__(self, *args, **kwargs):
 super(ValuesQuerySet, self).__init__(*args, **kwargs)
 # select_related isn't supported in values(). (FIXME -#3358)
 # QuerySet.clone() will also set up the _fields attribute with the
 # names of the model fields to select.
 def iterator(self):
-self.query.trim_extra_select(self.extra_names)
+if (not self.extra_names and
+len(self.field_names) != len(self.model._meta.fields)):
+self.query.trim_extra_select(self.extra_names)
 names = self.query.extra_select.keys() + self.field_names
 for row in self.query.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 initialising the rest of the
+Called by the _clone() method after initializing the rest of the
 instance.
 """
 self.extra_names = []
 if self._fields:
 if not self.query.extra_select:
 if (set(self.extra_names) != set(other.extra_names) or
 set(self.field_names) != set(other.field_names)):
 raise TypeError("Merging '%s' classes must involve the same values in each case."
 % self.__class__.__name__)
 class ValuesListQuerySet(ValuesQuerySet):
 def iterator(self):
 self.query.trim_extra_select(self.extra_names)
 if self.flat and len(self._fields) == 1:
 for row in self.query.results_iter():
 yield row[0]
 elif not self.query.extra_select:
 for row in self.query.results_iter():
-yield row
+yield tuple(row)
 else:
 # When extra(select=...) is involved, the extra cols come are
 # always at the start of the row, so we need to reorder the fields
 # to match the order in self._fields.
 names = self.query.extra_select.keys() + self.field_names
 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.results_iter()
 def _setup_query(self):
 """
 Sets up any special features of the query attribute.
-Called by the _clone() method after initialising the rest of the
+Called by the _clone() method after initializing the rest of the
 instance.
 """
 self.query = self.query.clone(klass=sql.DateQuery, setup=True)
 self.query.select = []
-self.query.add_date_select(self._field.column, self._kind, self._order)
+field = self.model._meta.get_field(self._field_name, many_to_many=False)
-if self._field.null:
+assert isinstance(field, DateField), "%r isn't a DateField." \
-self.query.add_filter(('%s__isnull' % self._field.name, True))
+% 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 = self._field
+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):
 super(EmptyQuerySet, self).__init__(model, query)
 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 iterator(self):
 # This slightly odd construction is because we need an empty generator
 # (it raises StopIteration immediately).
 yield iter([]).next()
-# QOperator, QNot, QAnd and QOr are temporarily retained for backwards
-# compatibility. All the old functionality is now part of the 'Q' class.
-class QOperator(Q):
-def __init__(self, *args, **kwargs):
-warnings.warn('Use Q instead of QOr, QAnd or QOperation.',
-DeprecationWarning, stacklevel=2)
-super(QOperator, self).__init__(*args, **kwargs)
-QOr = QAnd = QOperator
-def QNot(q):
-warnings.warn('Use ~q instead of QNot(q)', DeprecationWarning, stacklevel=2)
-return ~q
 def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0,
 requested=None):
 """
 Helper function that recursively returns an object with the specified
 related attributes already populated.
 """
 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
 index_end = index_start + len(klass._meta.fields)
-obj = klass(*row[index_start:index_end])
+fields = row[index_start:index_end]
+if not [x for x in fields if x is not None]:
+# If we only have a list of Nones, there was not related object.
+obj = None
+else:
+obj = klass(*fields)
 for f in klass._meta.fields:
-if (not f.rel or (not restricted and f.null) or
+if not select_related_descend(f, restricted, requested):
-(restricted and f.name not in requested) or f.rel.parent_link):
 continue
 if restricted:
 next = requested[f.name]
 else:
 next = None
 cached_row = get_cached_row(f.rel.to, row, index_end, max_depth,
 cur_depth+1, next)
 if cached_row:
 rel_obj, index_end = cached_row
-setattr(obj, f.get_cache_name(), rel_obj)
+if obj is not None:
+setattr(obj, f.get_cache_name(), rel_obj)
 return obj, index_end
 def delete_objects(seen_objs):
 """
 Iterate through a list of seen classes, and remove any instances that are
 referred to.
 """
-ordered_classes = seen_objs.keys()
+try:
-ordered_classes.reverse()
+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 = {}
 for cls in ordered_classes:
-seen_objs[cls] = seen_objs[cls].items()
+items = seen_objs[cls].items()
-seen_objs[cls].sort()
+items.sort()
+obj_pairs[cls] = items
-# Pre notify all instances to be deleted
-for pk_val, instance in seen_objs[cls]:
+# Pre-notify all instances to be deleted.
-dispatcher.send(signal=signals.pre_delete, sender=cls,
+for pk_val, instance in items:
-instance=instance)
+signals.pre_delete.send(sender=cls, instance=instance)
-pk_list = [pk for pk,instance in seen_objs[cls]]
+pk_list = [pk for pk,instance in items]
 del_query = sql.DeleteQuery(cls, connection)
 del_query.delete_batch_related(pk_list)
 update_query = sql.UpdateQuery(cls, connection)
-for field in cls._meta.fields:
+for field, model in cls._meta.get_fields_with_model():
-if field.rel and field.null and field.rel.to in seen_objs:
+if (field.rel and field.null and field.rel.to in seen_objs and
-update_query.clear_related(field, pk_list)
+filter(lambda f: f.column == field.column,
+field.rel.to._meta.fields)):
-# Now delete the actual data
+if model:
+sql.UpdateQuery(model, connection).clear_related(field,
+pk_list)
+else:
+update_query.clear_related(field, pk_list)
+# Now delete the actual data.
 for cls in ordered_classes:
-seen_objs[cls].reverse()
+items = obj_pairs[cls]
-pk_list = [pk for pk,instance in seen_objs[cls]]
+items.reverse()
+pk_list = [pk for pk,instance in items]
 del_query = sql.DeleteQuery(cls, connection)
 del_query.delete_batch(pk_list)
 # 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 seen_objs[cls]:
+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)
-dispatcher.send(signal=signals.post_delete, sender=cls,
+signals.post_delete.send(sender=cls, instance=instance)
-instance=instance)
 setattr(instance, cls._meta.pk.attname, None)
 transaction.commit_unless_managed()
 def insert_query(model, values, return_id=False, raw_values=False):
 """
 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, connection)
 query.insert_values(values, raw_values)
 return query.execute_sql(return_id)

changeset 323	ff1a9aa48cfd
parent 54	03e267d67478