| """ |
| The main QuerySet implementation. This provides the public API for the ORM. |
| """ |
| |
| 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, |
| deferred_class_factory, InvalidQuery) |
| from django.db.models.deletion import Collector |
| 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) |
| |
| # Cache db and model outside the loop |
| db = self.db |
| model = self.model |
| compiler = self.query.get_compiler(using=db) |
| for row in compiler.results_iter(): |
| if fill_cache: |
| obj, _ = get_cached_row(model, row, |
| index_start, using=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 = model(*row[index_start:aggregate_start]) |
| |
| # Store the source database of the object |
| obj._state.db = db |
| # This object came from the database; it's not being added. |
| obj._state.adding = False |
| |
| if extra_select: |
| for i, k in enumerate(extra_select): |
| setattr(obj, k, row[i]) |
| |
| # Add the aggregates to the model |
| if aggregate_select: |
| 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() |
| |
| collector = Collector(using=del_query.db) |
| collector.collect(del_query) |
| collector.delete() |
| |
| # 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: |
| if arg.default_alias in kwargs: |
| raise ValueError("The %s named annotation conflicts with the " |
| "default name for another annotation." |
| % arg.default_alias) |
| kwargs[arg.default_alias] = arg |
| |
| names = set(self.model._meta.get_all_field_names()) |
| for aggregate in kwargs: |
| if aggregate in names: |
| raise ValueError("The %s annotation conflicts with a field on " |
| "the model." % aggregate) |
| |
| |
| 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 f in self.query.extra: |
| self.extra_names.append(f) |
| elif f in self.query.aggregate_select: |
| 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, True) |
| 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) |
| if not hasattr(clone, "flat"): |
| # Only assign flat if the clone didn't already get it from 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 = [] |
| self.query.add_date_select(self._field_name, self._kind, self._order) |
| |
| 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, setup=setup, **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 |
| obj._state.adding = False |
| |
| 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 |
| |
| |
| 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): |
| # Mapping of attrnames to row column positions. Used for constructing |
| # the model using kwargs, needed when not all model's fields are present |
| # in the query. |
| model_init_field_names = {} |
| # A list of tuples of (column name, column position). Used for |
| # annotation fields. |
| annotation_fields = [] |
| |
| # Cache some things for performance reasons outside the loop. |
| db = self.db |
| compiler = connections[db].ops.compiler('SQLCompiler')( |
| self.query, connections[db], db |
| ) |
| need_resolv_columns = hasattr(compiler, 'resolve_columns') |
| |
| query = iter(self.query) |
| |
| # Find out which columns are model's fields, and which ones should be |
| # annotated to the model. |
| for pos, column in enumerate(self.columns): |
| if column in self.model_fields: |
| model_init_field_names[self.model_fields[column].attname] = pos |
| else: |
| annotation_fields.append((column, pos)) |
| |
| # Find out which model's fields are not present in the query. |
| skip = set() |
| for field in self.model._meta.fields: |
| if field.attname not in model_init_field_names: |
| 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 |
| # All model's fields are present in the query. So, it is possible |
| # to use *args based model instantation. For each field of the model, |
| # record the query column position matching that field. |
| model_init_field_pos = [] |
| for field in self.model._meta.fields: |
| model_init_field_pos.append(model_init_field_names[field.attname]) |
| if need_resolv_columns: |
| fields = [self.model_fields.get(c, None) for c in self.columns] |
| # Begin looping through the query values. |
| for values in query: |
| if need_resolv_columns: |
| values = compiler.resolve_columns(values, fields) |
| # Associate fields to values |
| if skip: |
| model_init_kwargs = {} |
| for attname, pos in model_init_field_names.iteritems(): |
| model_init_kwargs[attname] = values[pos] |
| instance = model_cls(**model_init_kwargs) |
| else: |
| model_init_args = [values[pos] for pos in model_init_field_pos] |
| instance = model_cls(*model_init_args) |
| if annotation_fields: |
| for column, pos in annotation_fields: |
| setattr(instance, column, values[pos]) |
| |
| instance._state.db = db |
| instance._state.adding = False |
| |
| yield instance |
| |
| 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 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) |
