diff -r 57b4279d8c4e -r 03e267d67478 app/django/db/models/manager.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/app/django/db/models/manager.py Fri Jul 18 18:22:23 2008 +0000 @@ -0,0 +1,145 @@ +import copy + +from django.db.models.query import QuerySet, EmptyQuerySet, insert_query +from django.dispatch import dispatcher +from django.db.models import signals +from django.db.models.fields import FieldDoesNotExist + +def ensure_default_manager(sender): + cls = sender + if not getattr(cls, '_default_manager', None) and not cls._meta.abstract: + # Create the default manager, if needed. + try: + cls._meta.get_field('objects') + raise ValueError, "Model %s must specify a custom Manager, because it has a field named 'objects'" % cls.__name__ + except FieldDoesNotExist: + pass + cls.add_to_class('objects', Manager()) + +dispatcher.connect(ensure_default_manager, signal=signals.class_prepared) + +class Manager(object): + # Tracks each time a Manager instance is created. Used to retain order. + creation_counter = 0 + + def __init__(self): + super(Manager, self).__init__() + # Increase the creation counter, and save our local copy. + self.creation_counter = Manager.creation_counter + Manager.creation_counter += 1 + self.model = None + + def contribute_to_class(self, model, name): + # TODO: Use weakref because of possible memory leak / circular reference. + self.model = model + setattr(model, name, ManagerDescriptor(self)) + if not getattr(model, '_default_manager', None) or self.creation_counter < model._default_manager.creation_counter: + model._default_manager = self + + def _copy_to_model(self, model): + """ + Makes a copy of the manager and assigns it to 'model', which should be + a child of the existing model (used when inheriting a manager from an + abstract base class). + """ + assert issubclass(model, self.model) + mgr = copy.copy(self) + mgr.model = model + return mgr + + ####################### + # PROXIES TO QUERYSET # + ####################### + + def get_empty_query_set(self): + return EmptyQuerySet(self.model) + + def get_query_set(self): + """Returns a new QuerySet object. Subclasses can override this method + to easily customize the behavior of the Manager. + """ + return QuerySet(self.model) + + def none(self): + return self.get_empty_query_set() + + def all(self): + return self.get_query_set() + + def count(self): + return self.get_query_set().count() + + def dates(self, *args, **kwargs): + return self.get_query_set().dates(*args, **kwargs) + + def distinct(self, *args, **kwargs): + return self.get_query_set().distinct(*args, **kwargs) + + def extra(self, *args, **kwargs): + return self.get_query_set().extra(*args, **kwargs) + + def get(self, *args, **kwargs): + return self.get_query_set().get(*args, **kwargs) + + def get_or_create(self, **kwargs): + return self.get_query_set().get_or_create(**kwargs) + + def create(self, **kwargs): + return self.get_query_set().create(**kwargs) + + def filter(self, *args, **kwargs): + return self.get_query_set().filter(*args, **kwargs) + + def complex_filter(self, *args, **kwargs): + return self.get_query_set().complex_filter(*args, **kwargs) + + def exclude(self, *args, **kwargs): + return self.get_query_set().exclude(*args, **kwargs) + + def in_bulk(self, *args, **kwargs): + return self.get_query_set().in_bulk(*args, **kwargs) + + def iterator(self, *args, **kwargs): + return self.get_query_set().iterator(*args, **kwargs) + + def latest(self, *args, **kwargs): + return self.get_query_set().latest(*args, **kwargs) + + def order_by(self, *args, **kwargs): + return self.get_query_set().order_by(*args, **kwargs) + + def select_related(self, *args, **kwargs): + return self.get_query_set().select_related(*args, **kwargs) + + def values(self, *args, **kwargs): + return self.get_query_set().values(*args, **kwargs) + + def values_list(self, *args, **kwargs): + return self.get_query_set().values_list(*args, **kwargs) + + def update(self, *args, **kwargs): + return self.get_query_set().update(*args, **kwargs) + + def reverse(self, *args, **kwargs): + return self.get_query_set().reverse(*args, **kwargs) + + def _insert(self, values, **kwargs): + return insert_query(self.model, values, **kwargs) + + def _update(self, values, **kwargs): + return self.get_query_set()._update(values, **kwargs) + +class ManagerDescriptor(object): + # This class ensures managers aren't accessible via model instances. + # For example, Poll.objects works, but poll_obj.objects raises AttributeError. + def __init__(self, manager): + self.manager = manager + + def __get__(self, instance, type=None): + if instance != None: + raise AttributeError, "Manager isn't accessible via %s instances" % type.__name__ + return self.manager + +class EmptyManager(Manager): + def get_query_set(self): + return self.get_empty_query_set()