--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/db/models/query.py Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,730 @@
+import warnings
+
+from django.conf import settings
+from django.db import connection, transaction, IntegrityError
+from django.db.models.fields import DateField, FieldDoesNotExist
+from django.db.models.query_utils import Q
+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
+EmptyResultSet = sql.EmptyResultSet
+
+class QuerySet(object):
+ "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
+
+ ########################
+ # PYTHON MAGIC METHODS #
+ ########################
+
+ 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):
+ return repr(list(self))
+
+ 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 __getitem__(self, k):
+ "Retrieve 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)
+ combined = self._clone()
+ combined.query.combine(other.query, sql.AND)
+ return combined
+
+ def __or__(self, other):
+ self._merge_sanity_check(other)
+ combined = self._clone()
+ 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()
+ index_start = len(extra_select)
+ for row in self.query.results_iter():
+ if fill_cache:
+ obj, _ = get_cached_row(self.model, row, index_start,
+ max_depth, requested=requested)
+ else:
+ obj = self.model(*row[index_start:])
+ for i, k in enumerate(extra_select):
+ setattr(obj, k, row[i])
+ yield obj
+
+ 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
+ simply returns the length of the cached results set to avoid multiple
+ SELECT COUNT(*) calls.
+ """
+ if self._result_cache is not None:
+ return len(self._result_cache)
+
+ return self.query.get_count()
+
+ def get(self, *args, **kwargs):
+ """
+ Performs the query and returns a single object matching the given
+ keyword arguments.
+ """
+ clone = self.filter(*args, **kwargs)
+ 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):
+ """
+ Create a new object with the given kwargs, saving it to the database
+ and returning the created object.
+ """
+ obj = self.model(**kwargs)
+ obj.save()
+ 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:
+ 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)
+ obj.save()
+ return obj, True
+ except IntegrityError, e:
+ return self.get(**kwargs), False
+
+ 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)), \
+ "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()
+
+ # 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.
+ 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()
+ for object in del_query[:CHUNK_SIZE]:
+ object._collect_sub_objects(seen_objs)
+
+ if not seen_objs:
+ break
+ delete_objects(seen_objs)
+
+ # 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.
+ """
+ query = self.query.clone(sql.UpdateQuery)
+ query.add_update_values(kwargs)
+ query.execute_sql(None)
+ transaction.commit_unless_managed()
+ self._result_cache = None
+ 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).
+ """
+ query = self.query.clone(sql.UpdateQuery)
+ query.add_update_fields(values)
+ query.execute_sql(None)
+ self._result_cache = None
+ _update.alters_data = True
+
+ ##################################################
+ # 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'."
+ # Let the FieldDoesNotExist exception propagate.
+ field = self.model._meta.get_field(field_name, many_to_many=False)
+ 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.
+ """
+ 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'):
+ return self._filter_or_exclude(None, filter_obj)
+ 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 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):
+ """
+ Add 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
+
+ ###################
+ # PRIVATE METHODS #
+ ###################
+
+ def _clone(self, klass=None, setup=False, **kwargs):
+ if klass is None:
+ klass = self.__class__
+ c = klass(model=self.model, query=self.query.clone())
+ 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 _merge_sanity_check(self, other):
+ """
+ Checks that we are merging two comparable queryset classes.
+ """
+ if self.__class__ is not other.__class__:
+ raise TypeError("Cannot merge querysets of different types ('%s' and '%s'."
+ % (self.__class__.__name__, other.__class__.__name__))
+
+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):
+ 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
+ instance.
+ """
+ self.extra_names = []
+ if self._fields:
+ if not self.query.extra_select:
+ field_names = list(self._fields)
+ else:
+ field_names = []
+ for f in self._fields:
+ if self.query.extra_select.has_key(f):
+ self.extra_names.append(f)
+ else:
+ field_names.append(f)
+ else:
+ # Default to all fields.
+ field_names = [f.attname for f in self.model._meta.fields]
+
+ self.query.add_fields(field_names, False)
+ self.query.default_cols = False
+ self.field_names = field_names
+
+ def _clone(self, klass=None, setup=False, **kwargs):
+ """
+ Cloning a ValuesQuerySet preserves the current fields.
+ """
+ c = super(ValuesQuerySet, self)._clone(klass, **kwargs)
+ c._fields = self._fields[:]
+ c.field_names = self.field_names
+ c.extra_names = self.extra_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)):
+ 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
+ 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
+ for row in self.query.results_iter():
+ data = dict(zip(names, row))
+ yield tuple([data[f] for f in self._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.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
+ 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)
+ if self._field.null:
+ self.query.add_filter(('%s__isnull' % self._field.name, True))
+
+ def _clone(self, klass=None, setup=False, **kwargs):
+ c = super(DateQuerySet, self)._clone(klass, False, **kwargs)
+ c._field = self._field
+ 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 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()
+
+# 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])
+ for f in klass._meta.fields:
+ if (not f.rel or (not restricted and f.null) or
+ (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)
+ 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()
+ ordered_classes.reverse()
+
+ for cls in ordered_classes:
+ seen_objs[cls] = seen_objs[cls].items()
+ seen_objs[cls].sort()
+
+ # Pre notify all instances to be deleted
+ for pk_val, instance in seen_objs[cls]:
+ dispatcher.send(signal=signals.pre_delete, sender=cls,
+ instance=instance)
+
+ pk_list = [pk for pk,instance in seen_objs[cls]]
+ 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:
+ if field.rel and field.null and field.rel.to in seen_objs:
+ update_query.clear_related(field, pk_list)
+
+ # Now delete the actual data
+ for cls in ordered_classes:
+ seen_objs[cls].reverse()
+ pk_list = [pk for pk,instance in seen_objs[cls]]
+ 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 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,
+ 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)
+