""" The main QuerySet implementation. This provides the public API for the ORM. """ from copy import deepcopy 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_dict = deepcopy(self.__dict__, memo) obj_dict['_iter'] = None obj = self.__class__() obj.__dict__.update(obj_dict) 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 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 = CollectedObjects(seen_objs) for object in del_query[:CHUNK_SIZE]: object._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 load_fields = only_load and only_load.get(klass) or 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 "" % (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)] = name return self._model_fields def transform_results(self, values): model_init_kwargs = {} annotations = () # 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]] = 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)